Norman Rostoker

Hybrid MHD model for a driven, ion-current FRC

Typical MHD models do not include the effects of a finite-electric field, finite gyro-radius, and gyro-period. The magnetohydrodynamic code, MACH2, is modified in one dimension to account for two-fluid behavior, in order to include these effects during the formation of a “driven”, field-reversed configuration (FRC). The simulation is run for a period of 150 μs, during which time an azimuthal ion current accelerates, the FRC forms, compresses radially and axially, and then begins to decay. Once the FRC is formed, an electron current develops, which sharpens the magnetic-field profile outside the null-field region. The equilibrium that is formed is characteristic of a Rigid Rotor.[1] The simulations also agree with prior experiments,[2] specifically the r-z shape of the FRC and the magnitude of the total current, including the ion and electron flows.

UCI Staged Z Pinch

The Staged Z-Pinch couples energy to a target, plasma-dynamically in stages. Our analysis considers this multi-shell z-pinch configuration driven by the ZOT Facility at the University of California, Irvine with predictions for a 2 MA, 1.8 μs krypton-liner shell and DT target of: Y≈4×1015 neutrons/pulse, G∼1 gain, nτ≈1015 cm−3-s, τ=2 ns, n=7×1023 cm−3, and Tion=10 keV.

A High Performance Field-Reversed Configuration Regime in the C-2 Device

A high temperature, stable, long-lived field-reversed configuration (FRC) plasma state has been produced in the C-2 device by dynamically colliding and merging two oppositely directed compact toroids, with combining effects of biasing edge plasma near the FRC separatrix from an end-plasma-gun with magnetic-mirror-plugs and of neutral-beam (NB) injection. The plasma-gun creates an inward radial electric field which mitigates the n = 2 rotational instability. The gun also produces E×B velocity shear in the FRC edge layer, which may explain observations of improved transport properties. The FRCs are nearly axisymmetric which enables fast ion confinement, and increasing NB power input clearly extends the FRC lifetime. The combined effects of the plasma-gun with mirror-plugs and of NB injection yield a new High Performance FRC regime with confinement times improved by factors 2 to 4 and FRC lifetimes extended from 1 to 3 ms.

UCI staged z-pinch

The UCI Staged z-Pinch is being assembled to study laboratory-scale, inertial-confinement fusion. The pinch load consists of an imploding-liner plasma that collapses onto a coaxial-fiber target. The fiber would be solid deuterium, cryogenically extruded through a 100-/spl mu/m diameter orifice. Initially, current flows through the outer liner. Near peak compression of the liner induces a current on the fiber with a time scale of the order of nanoseconds. Such rapid transfer of energy leads to an impressive increase in the fiber-internal energy, attaining conditions favorable for thermonuclear ignition. On the basis of simple flux compression our theoretical analysis and modeling suggests that fusion break-even is possible at several MA current (Rahman, Wessel, and Rostoker, Phys. Rev. Lett. 74, p.714, 1995), The experimental facility for this study is presently being commissioned at UCI. It consists of a low-inductance bank with the following design parameters: 50 /spl mu/Fd, 50 kV, 62.5 kJ, 1.9 /spl mu/sec risetime, and 2 MA into a short-circuit load.