Bab 5: Don't read this
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constgnt (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
and/or behind the projectile. The helical railgun is a cross between a railgun and a coilgun. They do not currently exist in a practical, usable form.
A helical railgun was built at MIT in 1980 and was powered by several banks of, for the time, large capacitors (approximately 4 farads). It was about 3 meters long, consisting of 2 meters of accelerating coil and 1 meter of decelerating coil. It was able to launch a glider or projectile about 500 meters.
Plasma railgunEdit
A plasma railgun is a linear accelerator and a plasma energy weapon which, like a projectile railgun, uses two long parallel electrodes to accelerate a "sliding short" armature. However, in a plasma railgun, the armature and ejected projectile consists of plasma, or hot, ionized, gas-like particles, instead of a solid slug of material. MARAUDER (Magnetically Accelerated Ring to Achieve Ultra-high Directed Energy and Radiation) is, or was, a United States Air Force Research Laboratory project concerning the development of a coaxial plasma railgun. It is one of several United States Government efforts to develop plasma-based projectiles. The first computer simulations occurred in 1990, and its first published experiment appeared on 1 August 1993.[71][72] As of 1993 the project appeared to be in the early experimental stages. The weapon was able to produce doughnut-shaped rings of plasma and balls of lightning that exploded with devastating effects when hitting their target.[73] The project's initial success led to it becoming classified, and only a few references to MARAUDER appeared after 1993.
scanning electron microscopy and other diagnostic techniques, they evaluated in detail the influence of plasmas on specific propellant materials.[114][113][115]
People's Republic of ChinaEdit
China is developing its own railgun system.[116] According to a CNBC report from U.S. intelligence, China's railgun system was first revealed in 2011, and ground testing began in 2014. Between 2015 and 2017, the weapon system gained the ability to strike over extended ranges with increased lethality. The weapon system was successfully mounted on a Chinese Navy ship in December 2017, with sea trials happening later.[117]
In early February 2018, pictures of what is claimed to be a Chinese railgun were published online. In the pictures the gun is mounted on the bow of a Type 072III-class landing ship Haiyangshan. Media suggests that the system is or soon will be ready for testing.[118][119] In March 2018, it was reported that China confirmed it had begun testing its electromagnetic rail gun at sea.[120][121]
IndiaEdit
In November 2017, India's Defence Research and Development Organisation carried out a successful test of a 12 mm square bore electromagnetic railgun. Tests of a 30 mm version are planned to be conducted. India aims to fire a one kilogram projectile at a velocity of more than 2,000 meters per second using a capacitor bank of 10 megajoules.[122][63] Electromagnetic guns and directed energy weapons are among the systems which Indian Navy aims to acquire in its modernisation plan up to 2030.[123]
Major difficultiesEdit
Major technological and operational hurdles must be overcome before railguns can be deployed:
Railgun durability: To date, public railgun demonstrations have not shown an ability to fire multiple full power shots from the same set of rails. However, the United States Navy has claimed hundreds of shots from the same set of rails. In a March 2014 statement to the Intelligence, Emerging Threats and Capabilities Subcommittee of the House Armed Services Committee, Chief of Naval Research Admiral Matthew Klunder stated, "Barrel life has increased from tens of shots to over 400, with a program path to achieve 1000 shots."[86] However, the Office of Naval Research (ONR) will not confirm that the 400 shots are full-power shots. Further, there is nothing published to indicate there are any high megajoule-class railguns with the capability of firing hundreds of full-power shots while staying within the strict operational parameters necessary to fire railgun shots accurately and safely. Railguns should be able to fire 6 rounds per minute with a rail life of about 3000 rounds, tolerating launch accelerations of tens of thousands of g's, extreme pressures and megaampere currents, but this is not feasible with current technology.[124]
Projectile guidance: A future capability critical to fielding a real railgun weapon is developing a robust guidance package that will allow the railgun to fire at distant targets or to hit incoming missiles. Developing such a package is a real challenge. The U.S. Navy's RFP Navy SBIR 2012.1 – Topic N121-102[125] for developing such a package gives a good overview of just how challenging railgun projectile guidance is:
The package must fit within the mass (< 2 kg), diameter (< 40 mm outer diameter), and volume (200 cm3) constraints of the projectile and do so without altering the center of gravity. It should also be able to survive accelerations of at least 20,000 g (threshold) / 40,000 g (objective) in all axes, high electromagnetic fields (E > 5,000 V/m, B > 2 T), and surface temperatures of > 800 deg C. The package should be able to operate in the presence of any plasma that may form in the bore or at the muzzle exit and must also be radiation hardened owing to exo-atmospheric flight. Total power consumption must be less than 8 watts (threshold)/5 watts (objective) and the battery life must be at least 5 minutes (from initial launch) to enable operation during the entire engagement. In order to be affordable, the production cost per projectile must be as low as possible, with a goal of less than $1,000 per unit.
On 22 June 2015, General Atomics' Electromagnetic Systems announced that projectiles with on-board electronics survived the whole railgun launch environment and performed their intended functions in four consecutive tests on 9 and 10 June at the U.S. Army's Dugway Proving Ground in Utah. The on-board electronics successfully measured in-bore accelerations and projectile dynamics, for several kilometers downrange, with the integral data link continuing to operate after the projectiles impacted the desert floor, which is essential for precision guidance.[126]
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
and/or behind the projectile. The helical railgun is a cross between a railgun and a coilgun. They do not currently exist in a practical, usable form.
A helical railgun was built at MIT in 1980 and was powered by several banks of, for the time, large capacitors (approximately 4 farads). It was about 3 meters long, consisting of 2 meters of accelerating coil and 1 meter of decelerating coil. It was able to launch a glider or projectile about 500 meters.
Plasma railgunEdit
A plasma railgun is a linear accelerator and a plasma energy weapon which, like a projectile railgun, uses two long parallel electrodes to accelerate a "sliding short" armature. However, in a plasma railgun, the armature and ejected projectile consists of plasma, or hot, ionized, gas-like particles, instead of a solid slug of material. MARAUDER (Magnetically Accelerated Ring to Achieve Ultra-high Directed Energy and Radiation) is, or was, a United States Air Force Research Laboratory project concerning the development of a coaxial plasma railgun. It is one of several United States Government efforts to develop plasma-based projectiles. The first computer simulations occurred in 1990, and its first published experiment appeared on 1 August 1993.[71][72] As of 1993 the project appeared to be in the early experimental stages. The weapon was able to produce doughnut-shaped rings of plasma and balls of lightning that exploded with devastating effects when hitting their target.[73] The project's initial success led to it becoming classified, and only a few references to MARAUDER appeared after 1993.
scanning electron microscopy and other diagnostic techniques, they evaluated in detail the influence of plasmas on specific propellant materials.[114][113][115]
People's Republic of ChinaEdit
China is developing its own railgun system.[116] According to a CNBC report from U.S. intelligence, China's railgun system was first revealed in 2011, and ground testing began in 2014. Between 2015 and 2017, the weapon system gained the ability to strike over extended ranges with increased lethality. The weapon system was successfully mounted on a Chinese Navy ship in December 2017, with sea trials happening later.[117]
In early February 2018, pictures of what is claimed to be a Chinese railgun were published online. In the pictures the gun is mounted on the bow of a Type 072III-class landing ship Haiyangshan. Media suggests that the system is or soon will be ready for testing.[118][119] In March 2018, it was reported that China confirmed it had begun testing its electromagnetic rail gun at sea.[120][121]
IndiaEdit
In November 2017, India's Defence Research and Development Organisation carried out a successful test of a 12 mm square bore electromagnetic railgun. Tests of a 30 mm version are planned to be conducted. India aims to fire a one kilogram projectile at a velocity of more than 2,000 meters per second using a capacitor bank of 10 megajoules.[122][63] Electromagnetic guns and directed energy weapons are among the systems which Indian Navy aims to acquire in its modernisation plan up to 2030.[123]
Major difficultiesEdit
Major technological and operational hurdles must be overcome before railguns can be deployed:
Railgun durability: To date, public railgun demonstrations have not shown an ability to fire multiple full power shots from the same set of rails. However, the United States Navy has claimed hundreds of shots from the same set of rails. In a March 2014 statement to the Intelligence, Emerging Threats and Capabilities Subcommittee of the House Armed Services Committee, Chief of Naval Research Admiral Matthew Klunder stated, "Barrel life has increased from tens of shots to over 400, with a program path to achieve 1000 shots."[86] However, the Office of Naval Research (ONR) will not confirm that the 400 shots are full-power shots. Further, there is nothing published to indicate there are any high megajoule-class railguns with the capability of firing hundreds of full-power shots while staying within the strict operational parameters necessary to fire railgun shots accurately and safely. Railguns should be able to fire 6 rounds per minute with a rail life of about 3000 rounds, tolerating launch accelerations of tens of thousands of g's, extreme pressures and megaampere currents, but this is not feasible with current technology.[124]
Projectile guidance: A future capability critical to fielding a real railgun weapon is developing a robust guidance package that will allow the railgun to fire at distant targets or to hit incoming missiles. Developing such a package is a real challenge. The U.S. Navy's RFP Navy SBIR 2012.1 – Topic N121-102[125] for developing such a package gives a good overview of just how challenging railgun projectile guidance is:
The package must fit within the mass (< 2 kg), diameter (< 40 mm outer diameter), and volume (200 cm3) constraints of the projectile and do so without altering the center of gravity. It should also be able to survive accelerations of at least 20,000 g (threshold) / 40,000 g (objective) in all axes, high electromagnetic fields (E > 5,000 V/m, B > 2 T), and surface temperatures of > 800 deg C. The package should be able to operate in the presence of any plasma that may form in the bore or at the muzzle exit and must also be radiation hardened owing to exo-atmospheric flight. Total power consumption must be less than 8 watts (threshold)/5 watts (objective) and the battery life must be at least 5 minutes (from initial launch) to enable operation during the entire engagement. In order to be affordable, the production cost per projectile must be as low as possible, with a goal of less than $1,000 per unit.
On 22 June 2015, General Atomics' Electromagnetic Systems announced that projectiles with on-board electronics survived the whole railgun launch environment and performed their intended functions in four consecutive tests on 9 and 10 June at the U.S. Army's Dugway Proving Ground in Utah. The on-board electronics successfully measured in-bore accelerations and projectile dynamics, for several kilometers downrange, gith the integral data link continuing to operate after the projectiles impacted the desert floor, which is essential for precision guidance.[126]
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
and/or behind the projectile. The helical railgun is a cross between a railgun and a coilgun. They do not currently exist in a practical, usable form.
A helical railgun was built at MIT in 1980 and was powered by several banks of, for the time, large capacitors (approximately 4 farads). It was about 3 meters long, consisting of 2 meters of accelerating coil and 1 meter of decelerating coil. It was able to launch a glider or projectile about 500 meters.
Plasma railgunEdit
A plasma railgun is a linear accelerator and a plasma energy weapon which, like a projectile railgun, uses two long parallel electrodes to accelerate a "sliding short" armature. However, in a plasma railgun, the armature and ejected projectile consists of plasma, or hot, ionized, gas-like particles, instead of a solid slug of material. MARAUDER (Magnetically Accelerated Ring to Achieve Ultra-high Directed Energy and Radiation) is, or was, a United States Air Force Research Laboratory project concerning the development of a coaxial plasma railgun. It is one of several United States Government efforts to develop plasma-based projectiles. The first computer simulations occurred in 1990, and its first published experiment appeared on 1 August 1993.[71][72] As of 1993 the project appeared to be in the early experimental stages. The weapon was able to produce doughnut-shaped rings of plasma and balls of lightning that exploded with devastating effects when hitting their target.[73] The project's initial success led to it becoming classified, and only a few references to MARAUDER appeared after 1993.
scanning electron microscopy and other diagnostic techniques, they evaluated in detail the influence of plasmas on specific propellant materials.[114][113][115]
People's Republic of ChinaEdit
China is developing its own railgun system.[116] According to a CNBC report from U.S. intelligence, China's railgun system was first revealed in 2011, and ground testing began in 2014. Between 2015 and 2017, the weapon system gained the ability to strike over extended ranges with increased lethality. The weapon system was successfully mounted on a Chinese Navy ship in December 2017, with sea trials happening later.[117]
In early February 2018, pictures of what is claimed to be a Chinese railgun were published online. In the pictures the gun is mounted on the bow of a Type 072III-class landing ship Haiyangshan. Media suggests that the system is or soon will be ready for testing.[118][119] In March 2018, it was reported that China confirmed it had begun testing its electromagnetic rail gun at sea.[120][121]
IndiaEdit
In November 2017, India's Defence Research and Development Organisation carried out a successful test of a 12 mm square bore electromagnetic railgun. Tests of a 30 mm version are planned to be conducted. India aims to fire a one kilogram projectile at a velocity of more than 2,000 meters per second using a capacitor bank of 10 megajoules.[122][63] Electromagnetic guns and directed energy weapons are among the systems which Indian Navy aims to acquire in its modernisation plan up to 2030.[123]
Major difficultiesEdit
Major technological and operational hurdles must be overcome before railguns can be deployed:
Railgun durability: To date, public railgun demonstrations have not shown an ability to fire multiple full power shots from the same set of rails. However, the United States Navy has claimed hundreds of shots from the same set of rails. In a March 2014 statement to the Intelligence, Emerging Threats and Capabilities Subcommittee of the House Armed Services Committee, Chief of Naval Research Admiral Matthew Klunder stated, "Barrel life has increased from tens of shots to over 400, with a program path to achieve 1000 shots."[86] However, the Office of Naval Research (ONR) will not confirm that the 400 shots are full-power shots. Further, there is nothing published to indicate there are any high megajoule-class railguns with the capability of firing hundreds of full-power shots while staying within the strict operational parameters necessary to fire railgun shots accurately and safely. Railguns should be able to fire 6 rounds per minute with a rail life of about 3000 rounds, tolerating launch accelerations of tens of thousands of g's, extreme pressures and megaampere currents, but this is not feasible with current technology.[124]
Projectile guidance: A future capability critical to fielding a real railgun weapon is developing a robust guidance package that will allow the railgun to fire at distant targets or to hit incoming missiles. Developing such a package is a real challenge. The U.S. Navy's RFP Navy SBIR 2012.1 – Topic N121-102[125] for developing such a package gives a good overview of just how challenging railgun projectile guidance is:
The package must fit within the mass (< 2 kg), diameter (< 40 mm outer diameter), and volume (200 cm3) constraints of the projectile and do so without altering the center of gravity. It should also be able to survive accelerations of at least 20,000 g (threshold) / 40,000 g (objective) in all axes, high electromagnetic fields (E > 5,000 V/m, B > 2 T), and surface temperatures of > 800 deg C. The package should be able to operate in the presence of any plasma that may form in the bore or at the muzzle exit and must also be radiation hardened owing to exo-atmospheric flight. Total power consumption must be less than 8 watts (threshold)/5 watts (objective) and the battery life must be at least 5 minutes (from initial launch) to enable operation during the entire engagement. In order to be affordable, the production cost per projectile must be as low as possible, with a goal of less than $1,000 per unit.
On 22 June 2015, General Atomics' Electromagnetic Systems announced that projectiles with on-board electronics survived the whole railgun launch environment and performed their intended functions in four consecutive tests on 9 and 10 June at the U.S. Army's Dugway Proving Ground in Utah. The on-board electronics successfully measured in-bore accelerations and projectile dynamics, for several kilometers downrange, with the integral data link continuing to operate after the projectiles impacted the desert floor, which is essential for precision guidance.[126]
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
First, it can be shown from the Biot–Savart law that at one end of a semi-infinite current-carrying wire, the magnetic field at a given perpendicular distance (�) from the end of the wire is given by[38]
�(�)=�0�4���^
Note this is if the wire runs from the location of the armature e.g. from x = 0 back to �=−∞ and � is measured relative to the axis of the wire.
So, if the armature connects the ends of two such semi-infinite wires separated by a distance, �, a fairly good approximation assuming the length of the wires is much larger than �, the total field from both wires at any point on the armature is:
�(�)=�0�4�(1�+1�−�)�^
where � is the perpendicular distance from the point on the armature to the axis of one of the wires.
Note that �^ between the rails is �^ assuming the rails are lying in the xy plane and run from x = 0 back to �=−∞ as suggested above.
Next, to evaluate the force on the armature, the above expression for the magnetic field on the armature can be used in conjunction with the Lorentz Force Law,
�=�∫dℓ×�(�)
To give the force as
�=�∫��−�dℓ×�0�4�(1�+1�−�)�^=�0�22�ln(�−��)�^
thin wires or "filaments". With this approximation, the magnitude of the force vector can be determined from a form of the Biot–Savart law and a result of the Lorentz force. The force can be derived mathematically in terms of the permeability constant (�0), the radius of the rails (which are assumed to be circular in cross section) (�), the distance between the central axes of the rails (�) and the current (�) as described below.
and/or behind the projectile. The helical railgun is a cross between a railgun and a coilgun. They do not currently exist in a practical, usable form.
A helical railgun was built at MIT in 1980 and was powered by several banks of, for the time, large capacitors (approximately 4 farads). It was about 3 meters long, consisting of 2 meters of accelerating coil and 1 meter of decelerating coil. It was able to launch a glider or projectile about 500 meters.
Plasma railgunEdit
A plasma railgun is a linear accelerator and a plasma energy weapon which, like a projectile railgun, uses two long parallel electrodes to accelerate a "sliding short" armature. However, in a plasma railgun, the armature and ejected projectile consists of plasma, or hot, ionized, gas-like particles, instead of a solid slug of material. MARAUDER (Magnetically Accelerated Ring to Achieve Ultra-high Directed Energy and Radiation) is, or was, a United States Air Force Research Laboratory project concerning the development of a coaxial plasma railgun. It is one of several United States Government efforts to develop plasma-based projectiles. The first computer simulations occurred in 1990, and its first published experiment appeared on 1 August 1993.[71][72] As of 1993 the project appeared to be in the early experimental stages. The weapon was able to produce doughnut-shaped rings of plasma and balls of lightning that exploded with devastating effects when hitting their target.[73] The project's initial success led to it becoming classified, and only a few references to MARAUDER appeared after 1993.
scanning electron microscopy and other diagnostic techniques, they evaluated in detail the influence of plasmas on specific propellant materials.[114][113][115]
People's Republic of ChinaEdit
China is developing its own railgun system.[116] According to a CNBC report from U.S. intelligence, China's railgun system was first revealed in 2011, and ground testing began in 2014. Between 2015 and 2017, the weapon system gained the ability to strike over extended ranges with increased lethality. The weapon system was successfully mounted on a Chinese Navy ship in December 2017, with sea trials happening later.[117]
In early February 2018, pictures of what is claimed to be a Chinese railgun were published online. In the pictures the gun is mounted on the bow of a Type 072III-class landing ship Haiyangshan. Media suggests that the system is or soon will be ready for testing.[118][119] In March 2018, it was reported that China confirmed it had begun testing its electromagnetic rail gun at sea.[120][121]
IndiaEdit
In November 2017, India's Defence Research and Development Organisation carried out a successful test of a 12 mm square bore electromagnetic railgun. Tests of a 30 mm version are planned to be conducted. India aims to fire a one kilogram projectile at a velocity of more than 2,000 meters per second using a capacitor bank of 10 megajoules.[122][63] Electromagnetic guns and directed energy weapons are among the systems which Indian Navy aims to acquire in its modernisation plan up to 2030.[123]
Major difficultiesEdit
Major technological and operational hurdles must be overcome before railguns can be deployed:
Railgun durability: To date, public railgun demonstrations have not shown an ability to fire multiple full power shots from the same set of rails. However, the United States Navy has claimed hundreds of shots from the same set of rails. In a March 2014 statement to the Intelligence, Emerging Threats and Capabilities Subcommittee of the House Armed Services Committee, Chief of Naval Research Admiral Matthew Klunder stated, "Barrel life has increased from tens of shots to over 400, with a program path to achieve 1000 shots."[86] However, the Office of Naval Research (ONR) will not confirm that the 400 shots are full-power shots. Further, there is nothing published to indicate there are any high megajoule-class railguns with the capability of firing hundreds of full-power shots while staying within the strict operational parameters necessary to fire railgun shots accurately and safely. Railguns should be able to fire 6 rounds per minute with a rail life of about 3000 rounds, tolerating launch accelerations of tens of thousands of g's, extreme pressures and megaampere currents, but this is not feasible with current technology.[124]
Projectile guidance: A future capability critical to fielding a real railgun weapon is developing a robust guidance package that will allow the railgun to fire at distant targets or to hit incoming missiles. Developing such a package is a real challenge. The U.S. Navy's RFP Navy SBIR 2012.1 – Topic N121-102[125] for developing such a package gives a good overview of just how challenging railgun projectile guidance is:
The package must fit within the mass (< 2 kg), diameter (< 40 mm outer diameter), and volume (200 cm3) constraints of the projectile and do so without altering the center of gravity. It should also be able to survive accelerations of at least 20,000 g (threshold) / 40,000 g (objective) in all axes, high electromagnetic fields (E > 5,000 V/m, B > 2 T), and surface temperatures of > 800 deg C. The package should be able to operate in the presence of any plasma that may form in the bore or at the muzzle exit and must also be radiation hardened owing to exo-atmospheric flight. Total power consumption must be less than 8 watts (threshold)/5 watts (objective) and the battery life must be at least 5 minutes (from initial launch) to enable operation during the entire engagement. In order to be affordable, the production cost per projectile must be as low as possible, with a goal of less than $1,000 per unit.
On 22 June 2015, General Atomics' Electromagnetic Systems announced that projectiles with on-board electronics survived the whole railgun launch environment and performed their intended functions in four consecutive tests on 9 and 10 June at the U.S. Army's Dugway Proving Ground in Utah. The on-board electronics successfully measured in-bore accelerations and projectile dynamich for several kilometers downrange, gith the integral data link continuing to operate after the projectiles impacted the desert floor, which is essential for precision guidance.[126]
Status Power Mingguan
-- Peringkat
Power 
-- Power
stone