Test ion transport in a collisional, field-reversed configuration

Diffusion of test-ions in a flux-coil generated, collisional, field-reversed configuration is measured via time-resolved tomographic reconstruction of Ar+ optical emission in the predominantly nitrogen plasma. Azimuthal test ion diffusion across magnetic field lines is found to be classical during the stable period of the discharge. Test ion radial confinement is enhanced by a radial electric field, reducing the observed outward radial transport rate below predictions based solely on classical cross-field diffusion rates. Test ion diffusion is ∼500m2s-1 during the stable period of the discharge. The electric field inferred from plasma potential measurements and from equilibrium calculations is consistent with the observed reduction in argon transport. © 2014 IOP Publishing Ltd

Generation and transport of a low energy intense ion beam

The paper describes experiments on the generation and transport of a low energy (70-120 keV), high intensity (10-30 A/cm(2)) microsecond duration H+ ion beam (IB) in vacuum and plasma. The IB was generated in a magnetically insulated diode (MID) with an applied radial B field and an active hydrogen-puff ion source. The annular IB, with an initial density of j(i)similar to10-20 A/cm(2) at the anode surface, was ballistically focused to a current density in the focal plane of 50-80 A/cm(2). The postcathode collimation and transport of the converging IB were provided by the combination of a "concave" toroidal magnetic lens followed by a straight transport solenoid section. With optimized MID parameters and magnetic fields in the lens/solenoid system, the overall efficiency of IB transport at the exit of the solenoid 1 m from the anode was similar to 50% with an IB current density of 20 A/cm(2). Two-dimensional computer simulations of post-MID IB transport supported the optimization of system parameters. (C) 2004 American Institute of Physics

Generation and transport of a low energy intense ion beam

The paper describes experiments on the generation and transport of a low energy (70-120 keV), high intensity (10-30 A/cm(2)) microsecond duration H+ ion beam (IB) in vacuum and plasma. The IB was generated in a magnetically insulated diode (MID) with an applied radial B field and an active hydrogen-puff ion source. The annular IB, with an initial density of j(i)similar to10-20 A/cm(2) at the anode surface, was ballistically focused to a current density in the focal plane of 50-80 A/cm(2). The postcathode collimation and transport of the converging IB were provided by the combination of a "concave" toroidal magnetic lens followed by a straight transport solenoid section. With optimized MID parameters and magnetic fields in the lens/solenoid system, the overall efficiency of IB transport at the exit of the solenoid 1 m from the anode was similar to 50% with an IB current density of 20 A/cm(2). Two-dimensional computer simulations of post-MID IB transport supported the optimization of system parameters. (C) 2004 American Institute of Physics

Dynamic Formation of a Hot Field Reversed Configuration with Improved Confinement by Supersonic Merging of Two Colliding High-β Compact Toroids

A hot stable field-reversed configuration (FRC) has been produced in the C-2 experiment by colliding and merging two high-beta plasmoids preformed by the dynamic version of field-reversed theta-pinch technology. The merging process exhibits the highest poloidal flux amplification obtained in a magnetic confinement system (over tenfold increase). Most of the kinetic energy is converted into thermal energy with total temperature (T(i) + T(e)) exceeding 0.5 keV. The final FRC state exhibits a record FRC lifetime with flux confinement approaching classical values. These findings should have significant implications for fusion research and the physics of magnetic reconnection

Formation of a long-lived hot field reversed configuration by dynamically merging two colliding high-beta compact toroids

A high temperature field reversed configuration (FRC) has been produced in the newly built, world's largest compact toroid (CT) facility, C-2, by colliding and merging two high-beta CTs produced using the advanced field-reversed theta-pinch technology. This long-lived, stable merged state exhibits the following key properties: (1) apparent increase in the poloidal flux from the first pass to the final merged state, (2) significantly improved confinement compared to conventional theta-pinch FRCs with flux decay rates approaching classical values in some cases, (3) strong conversion from kinetic energy into thermal energy with total temperature (T(e)+T(i)) exceeding 0.5 keV, predominantly into the ion channel. Detailed modeling using a new 2-D resistive magnetohydrodynamic (MHD) code, LamyRidge, has demonstrated, for the first time, the formation, translation, and merging/reconnection dynamics of such extremely high-beta plasmas. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3574380

Dynamic Formation of a Hot Field Reversed Configuration with Improved Confinement by Supersonic Merging of Two Colliding High-beta Compact Toroids

A hot stable field-reversed configuration (FRC) has been produced in the C-2 experiment by colliding and merging two high-beta plasmoids preformed by the dynamic version of field-reversed theta-pinch technology. The merging process exhibits the highest poloidal flux amplification obtained in a magnetic confinement system (over tenfold increase). Most of the kinetic energy is converted into thermal energy with total temperature (T(i) + T(e)) exceeding 0.5 keV. The final FRC state exhibits a record FRC lifetime with flux confinement approaching classical values. These findings should have significant implications for fusion research and the physics of magnetic reconnection