Method of and apparatus for accelerating a projectile
First Claim
1. Apparatus for accelerating a projectile comprising means forming a confined path having a longitudinal axis along which the projectile traverses, and means for supplying a pulsed high pressure, high velocity plasma jet to the path from outside the path and to the rear of the projectile as the projectile traverses the path to accelerate the projectile along the path, the jet entering the confined path at a non-zero acute angle relative to the confined path axis, the projectile and confined path geometries being such that the plasma to the rear of the projectile has a tendency to leak around the projectile so the leaked plasma is in front of the projectile, the plasma in front of the projectile tending to accumulate and to impede the acceleration of the projectile, and means for venting the plasma in front of the projectile from the confined path to substantially overcome the tendency of the leaked plasma to accumulate and impede the projectile acceleration.
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Abstract
A projectile is accelerated along a confined path by supplying a pulsed high pressure, high velocity plasma jet to the rear of the projectile as the projectile traverses the path. The jet enters the confined path at a non-zero angle relative to the projectile path. The pulse is derived from a dielectric capillary tube having an interior wall from which plasma forming material is ablated in response to a discharge voltage. The projectile can be accelerated in response to the kinetic energy in the plasma jet or in response to a pressure increase of gases in the confined path resulting from the heat added to the gases by the plasma.
82 Citations
41 Claims
- 1. Apparatus for accelerating a projectile comprising means forming a confined path having a longitudinal axis along which the projectile traverses, and means for supplying a pulsed high pressure, high velocity plasma jet to the path from outside the path and to the rear of the projectile as the projectile traverses the path to accelerate the projectile along the path, the jet entering the confined path at a non-zero acute angle relative to the confined path axis, the projectile and confined path geometries being such that the plasma to the rear of the projectile has a tendency to leak around the projectile so the leaked plasma is in front of the projectile, the plasma in front of the projectile tending to accumulate and to impede the acceleration of the projectile, and means for venting the plasma in front of the projectile from the confined path to substantially overcome the tendency of the leaked plasma to accumulate and impede the projectile acceleration.
- 3. Apparatus for accelerating a projectile comprising means forming a confined path having a longitudinal axis along which the projectile traverses, and means for supplying a pulsed high pressure, high velocity plasma jet to the path from outside the path and to the rear of the projectile as the projectile traverses the path to accelerate the projectile along the path, the jet entering the confined path at a non-zero acute angle relative to the confined path axis, the means for supplying a pulsed high pressure, high velocity plasma jet to the path including a tube having an interior wall forming a capillary passage, means for applying a discharge voltage between spaced regions along the length of the interior wall while a dielectric ionizable substance is between the regions, the dielectric substance including at least one element that is ionized to form a plasma in response to the discharge voltage being applied between the spaced regions, the diametric length across the passage being short relative to the distance between the spaced regions, first and second ends of the passage being respectively open and blocked while the discharge voltage is applied between the spaced regions to respectively enable and prevent the flow of plasma through them, the plasma forming an electric discharge channel between the spaced regions while the discharge voltage is applied between the regions, ohmic dissipation occurring in the electric discharge channel in response to the discharge voltage being applied between the regions to produce a high pressure in the passage to cause the plasma in the passage to flow longitudinally in the passage and through the first end to form the pulsed plasma jet.
- 6. Apparatus for accelerating a projectile comprising means forming a confined path having a longitudinal axis along which the projectile traverses, and means for supplying a pulsed high pressure, high velocity plasma jet to the path from outside the path and to the rear of the projectile as the projectile traverses the path to accelerate the projectile along the path, the jet entering the confined path at a non-zero acute angle relative to the confined path axis, a plurality of the supplying means being located at spaced longitudinal regions along the path, and means for synchronizing the activation of the jets at each of the spaced regions so that at each of the longitudinal regions a pulse of the high pressure, high velocity plasma is applied to the rear of the projectile immediately after the projectile has traversed each of the longitudinal regions, the projectile and confined path geometries being such that the high velocity plasma applied to the rear of the projectile leaks around the projectile so some of the plasma is in front of the projectile to tend to impede acceleration of the projectile in the path, and means between at least some of said spaced longitudinal regions for venting the plasma leaking around the projectile from the confined path.
- 9. Apparatus for accelerating a projectile comprising means forming a confined path having a longitudinal axis along which the projectile traverses, means for accelerating the projectile from rest in the path, a plurality of cascaded intermediate velocity stages for accelerating the projectile from non-free to free flight in the path downstream of the means for accelerating from rest, a plurality of cascaded high velocity stages for accelerating the projectile in the path downstream of the plural intermediate stages, each of the intermediate stages including means for applying a pulsed plasma jet to the rear of the projectile, each of the high velocity stages including means for supplying plasma to the sides of the projectile as the projectile traverses the particular high velocity stage.
- 12. Apparatus for accelerating a projectile comprising means forming a confined path having a longitudinal axis along which the projectile traverses, and means for supplying a pulsed high pressure, high velocity plasma jet to the path from outside the path and to the rear of the projectile as the projectile traverses the path to accelerate the projectile along the path, the jet entering the confined path at a non-zero acute angle relative to the confined path axis, the means for supplying comprising a tube having a longitudinal axis displaced from the confined path axis by the acute angle, the tube having an inner diameter including a dielectric ionizable substance, and means for applying a discharge voltage to the substance between displaced regions along the tube longitudinal axis to cause the substance to be ionized to form the plasma inside of the tube, the tube being dimensioned so that the plasma formed therein in response to the discharge voltage has a high velocity and high pressure to form the jet, the tube having a closed first end while the plasma is formed therein and a second end including an orifice into the confined path, the tube longitudinal axis being displaced from the confined path by said angle so that the jet propagates along the longitudinal axis of the tube and through the orifice into the confined path generally in the same direction as the projectile is being accelerated.
- 16. A method of accelerating a projectile along a confined path having a longitudinal axis along which the projectile traverses, comprising supplying a pulse of high pressure, high velocity plasma to the path behind the projectile as the projectile traverses the path by supplying a jet of the plasma to the confined path from a source located outside of the confined path so the plasma enters the path at a non-zero acute angle relative to the axis, the jet being derived by applying an electric discharge between spaced regions along a longitudinal axis of a capillary passage, blocking one end of said passage while the discharge is occurring, an electric discharge channel being formed by the plasma in the passage between the spaced regions in response to the applied electric discharge, ohmic dissipation occurring in the electric discharge channel in response to the applied electric discharge to produce a high pressure in the passage to cause plasma to flow longitudinally in the passage and through an orifice in an end of the passage opposite from the blocked one end, the plasma flowing through the orifice into the confined path to form the jet.
- 24. Apparatus for accelerating a projectile comprising means forming a confined path having a longitudinal axis along which the projectile traverses, and means for supplying a pulsed high pressure, high velocity plasma jet to the path from outside the path and to the rear of the projectile as the projectile traverses the path to accelerate the projectile along the path, the jet entering the confined path at a non-zero acute angle relative to the confined path axis, the supplying means including a capillary passage having a longitudinal axis, said passage having one closed end and an orifice at the other end into the confined path, means for applying a discharge voltage between spaced longitudinal regions of the passage in the direction of the passage longitudinal axis to form a plasma in the passage, an electric discharge channel being formed by the plasma in the passage between the spaced passage regions while the discharge voltage is applied between the spaced regions, said one end being closed while the discharge is occurring, ohmic dissipation occurring in the electric discharge channel while the discharge voltage is applied between the spaced regions to produce a high pressure in the passage to cause plasma to flow longitudinally in the passage and through the orifice to form the jet that enters the confined path.
Specification