Provided are methods and devices for compression of a spheromak plasma (e.g., deuterium-trirtium (D-T)-derived) in a magnetic well configured within a plasma combustion chamber using an induction coil axially adjacent to the plasma, wherein a moveable member (e.g., piston, cam and follower) drives the induction coil toward the plasma, pushing the plasma via magnetic pressure into the magnetic well and compressing the plasma substantially adiabatically (e.g., coil motion is well below the plasma sound speed). The compression quickly increases both plasma density and temperature past the point of ignition, and after plasma burn, the coil is backed-off to allow the plasma to re-expand, providing for refueling and repetition of the compression cycle. Additionally provided are spaced annular plasma formation electrodes, suitably configured for generating and injecting magnetized plasma into a plasma combustion chamber. Preferably, spaced annular plasma formation electrodes are used in combination with moveable compression members as disclosed herein. 1. A device for compression of a compact plasma, comprising: a variable-volume plasma combustion chamber defined by a blanket wall and a movable compression member surface; plasma formation and injecting means in communication with the combustion chamber; a plurality of magnetic field coils, positioned outside the blanket wall and suitably configured to provide for a magnetic well within the combustion chamber; a moveable compression member having at least one compression member magnetic field coil, the compression member and field coil moveable to vary the volume within the compression chamber; and compression member positioning means suitable, in operation with the compression member and field coil, to provide for cycled positioning of the compression member to provide for cycled compression and decompression of plasma within the compression chamber. 2. The device of claim 1, wherein the plasma formation and injecting means comprises a pair of spaced annular parallel formation electrodes, suitably configured for generating and injecting magnetized compact toroidal plasma into the combustion chamber. 3. The device of claim 1, wherein the magnetic well is suitable for magnetically isolating plasma from the blanket wall of the combustion chamber, and wherein the at least one compression member magnetic field coil is suitably configured to provide for magnetic isolation of the plasma from the compression member surface. 4. The device of claim 1, wherein the moveable-member comprises at least one piston, each having at least one attached or integral magnetic field coil. 5. The device of claim 4, comprising a cam and a cam follower, the cam follower in operative communication between the cam and the piston to provide for cycled positioning of the piston within the combustion chamber. 6. The device of claim 1, wherein the combustion chamber comprises a divertor opening, the device further comprising a divertor portion with a divertor chamber in flow communication with the combustion chamber via the divertor opening. 7. The device of claim 6, wherein the diverting chamber is defined by at least one divertor blanket wall and at least one divertor target surface suitably configured to receive hot particles from the combustion chamber, and wherein the divertor comprises a plurality of divertor magnetic field coils, and at least one exhaust gas port. 8. The device of claim 7, wherein the divetor comprises a divertor shielding plug having a blanket wall, the diverter shielding plug and blanket wall suitably configured to shield the internal diverter chamber surfaces from particle bombardment from the combustion chamber. 9. The device of claim 1, wherein the plasma comprises a quasi-steady state spheromak plasma having approximately equal magnitudes of toroidal and poloidal magnetic field. 10. The device of claim 1, wherein the blanket wall of the combustion chamber comprises a combustion chamber-proximal shield layer and a blanket layer comprising channels suitably configured to provide for conveyance of a particle absorbing blanket fluid to provide for capturing of plasma-derived particles and/or heat flux emitted from the combustion chamber. 11. The device of claim 1, wherein the moveable compression member comprises means for capturing neutrons and protecting the compression member coil(s) therefrom. 12. The device of claim 11, comprising blanket means. 13. A device for compression of a compact toroidal plasma (spheromak) for fusion-mediated neutron generation, comprising: a variable-volume plasma combustion chamber defined by a blanket wall and a movable compression member surface, the combustion chamber comprising a divertor opening, the combustion chamber blanket wall comprising a combustion chamber-proximal shield layer and a blanket layer comprising at least one channel suitably configured to provide for conveyance of a neutron absorbing blanket fluid to provide for capturing of plasma-derived neutron flux emitted from the combustion chamber; a divertor portion having a divertor chamber in flow communication with the combustion chamber via the divertor opening; spheromak plasma formation and injecting means in communication with the combustion chamber, the formation and injecting means suitable for generating and injecting a quasi-steady state spheromak plasma into the combustion chamber; a plurality of magnetic field coils, positioned outside the blanket wall and suitably configured to provide for a magnetic well within the combustion chamber, the magnetic well suitable for magnetically isolating the spheromak plasma from the blanket wall of the combustion chamber; a moveable compression member having at least one compression member magnetic field coil, the compression member and field coil(s) moveable to vary the volume within the compression chamber, the compression member magnetic field coil suitably configured to provide for magnetic isolation of the spheromak plasma from the compression member surface; and compression member positioning means suitable, in operation with the compression member and compression member field coil, to provide for cycled positioning of the compression member to provide for cycled compression and decompression of plasma within the compression chamber. CROSS-REFERENCE TO RELATED APPLICATIONS: This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 61/287,170, filed Dec. 16, 2009 and entitled FUSION INTERNAL COMBUSTION ENGINE, which is incorporated by reference herein in its entirety. STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH: The invention was made with government support under Contract No. DE-FG02-06ER84449 from the United States Department of Energy (DOE). The United States government has certain rights in the invention. FIELD OF THE INVENTION: The present invention relates generally to the use of a magnetic coil contained in a moving member (e.g., piston) to adiabatically compress a magnetized plasma (e.g., containing deuterium and tritium fuel), to a point where plasma pressure is sufficient to achieve ignition thereof, and in more particular aspects, the compression drives the plasma temperature and density to fusion regimes, resulting in steady-state fusion power that is captured directly or in a thermal cycle to drive, for example, a turbine. Certain aspects relate to the use of such compressed plasma as a neutron source or as an energy source by capturing the neutrons in a blanket surrounding the combustion chamber. DETAILED DESCRIPTION: Overview. Provided are methods and devices for compression of a spheromak plasma in a magnetic well configured within a plasma combustion chamber using an induction coil axially adjacent to the plasma, wherein a moveable member (e.g., piston, cam and follower) drives the induction coil toward the plasma, pushing the plasma via magnetic pressure into the magnetic well and compressing the plasma substantially adiabatically. The compression quickly increases both plasma density and temperature past the point of ignition, and after plasma burn, the coil is backed-off to allow the plasma to re-expand, providing for refueling and repetition of the compression cycle. Additionally provided are spaced annular plasma formation electrodes, suitably configured for generating and injecting magnetized plasma into a plasma combustion chamber.