Method of converging plasma pistons
A magnetic confinement system includes a magnetic mirror device that includes a chamber to hold a target plasma and a coil arrangement to generate a magnetic field configuration in the chamber to confine the target plasma in cylindrically-symmetric form in the chamber, the magnetic field configuration having open ends. The magnetic confinement system further includes plasma guns to generate plasma pistons and project the plasma pistons at the open ends of the magnetic field configuration. In operation, the plasma pistons converge towards each other to close the open ends of the magnetic field configuration and to compress and heat the target plasma.
1 . A method for magnetic confinement of a plasma, the method comprising:
a) confining a target plasma with a magnetic mirror device, the magnetic mirror device including a chamber and a coil arrangement, the chamber holding the target plasma, the coil arrangement generating a magnetic field configuration in the chamber to confine the target plasma in cylindrically-symmetric form in the chamber, the magnetic field configuration having open ends and including a longitudinal magnetic field, the coil arrangement including plural coils arranged along a length of the chamber to generate the longitudinal magnetic field to confine the target plasma radially, the magnetic field configuration strengthened at the ends of the magnetic field configuration to form magnetic mirrors;
b) converging plasma pistons towards each other and along a longitudinal axis of the chamber to close the open ends of the magnetic field configuration and to compress and heat the target plasma;
c) adjusting current through the plural coils of the coil arrangement as the plasma pistons enter the chamber, the coils including end coils at ends of the target plasma and central coils between the end coils, wherein the adjusting the current includes relaxing current in the end coils to relax the magnetic mirrors so as to accommodate the converging plasma piston; and
d) electromagnetically pinning the plasma pistons in place at the target plasma.
2 . The method of claim 1 , further comprising generating the plasma pistons and projecting the plasma pistons at the open ends of the magnetic field configuration using plasma guns.
3 . The method of claim 2 , further comprising stabilizing the plasma pistons with a central conductor, wherein:
the plasma guns comprise a first plasma gun and a second plasma gun, and
the central conductor extends through the chamber between the first plasma gun and the second plasma gun.
4 . The method of claim 3 , wherein the central conductor is electrically coupled to a central electrode of the first plasma gun and a central electrode of the second plasma gun, and wherein projecting the plasma pistons includes passing a current from a shell electrode of the first plasma gun through one of the plasma pistons and via the central conductor through another of the plasma pistons to a shell electrode of the second plasma gun.
5 . The method of claim 2 , wherein the plasma guns are coaxial railguns.
6 . The method of claim 1 , further comprising further compressing the target plasma radially.
7 . The method of claim 6 , wherein further compressing the target plasma radially comprises increasing the longitudinal magnetic field about the target plasma.
8 . The method of claim 1 , wherein pinning the plasma pistons in place comprises holding the plasma pistons in position at the target plasma after compression and heating of the target plasma.
9 . The method of claim 1 , wherein the target plasma is confined in a field-reversed configuration.
10 . The method of claim 1 , wherein the target plasma is a spheromak.
11 . The method of claim 1 , wherein each of the plasma pistons comprises thermonuclear fuel.
12 . The method of claim 1 , wherein each of the plasma pistons comprises a composition different from that of the target plasma.
13 . The method of claim 1 , wherein each of the plasma pistons comprises a series of plasma pistons.
14 . The method of claim 1 , wherein the target plasma comprises thermonuclear fuel.
15 . The method of claim 1 , wherein the plasma pistons are electromagnetically pinned in place at the target plasma by reversing current direction in the end coils while maintaining current direction in the central coils to provide cusp magnetic fields to pin the plasma pistons in place at the target plasma.
16 . The method of claim 1 , wherein the plasma pistons are electromagnetically pinned in place at the target plasma by forcing current through the plasma pistons to provide a Lorentz force to hold the plasma pistons in place at the target plasma.
17 . The method of claim 1 , wherein the coil arrangement is configured to modify the magnetic field configuration progressively to maintain compression of, or further compress, the target plasma via the plasma pistons.
18 . The method of claim 1 , wherein the coil arrangement is configured to modify the magnetic field configuration progressively to maintain compression of, or further compress, the plasma pistons.
19 . A method for magnetic confinement of a plasma, the method comprising:
confining a target plasma with a magnetic mirror device, the magnetic mirror device including a chamber and a coil arrangement, the chamber holding the target plasma, the coil arrangement generating a magnetic field configuration in the chamber to confine the target plasma in cylindrically-symmetric form in the chamber, the magnetic field configuration having open ends;
generating plasma pistons and projecting the plasma pistons at the open ends of the magnetic field configuration using plasma guns, the plasma pistons converging towards each other to close the open ends of the magnetic field configuration and to compress and heat the target plasma; and
stabilizing the plasma pistons with a central conductor, wherein the plasma guns comprise a first plasma gun and a second plasma gun, wherein the central conductor is electrically coupled to a central electrode of the first plasma gun and a central electrode of the second plasma gun and extends through the chamber between the first plasma gun and the second plasma gun, and wherein projecting the plasma pistons includes passing a current from a shell electrode of the first plasma gun through one of the plasma pistons and via the central conductor through another of the plasma pistons to a shell electrode of the second plasma gun.