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Inertial electrostatic confinement (IEC) systems are predicated on a nonequilibrium ion distribution function. Coulomb collisions between ions cause this distribution to relax to a Maxwellian on the ion–ion collisional time scale. The power required to prevent this relaxation and maintain the IEC configuration for times beyond the ion–ion collisional time scale is shown to be greater than the fusion power produced. It is concluded that IEC systems show little promise as a basis for the development of commercial electric power plants.

The goal for advanced steady-state operation in ITER should be to demonstrate the operation of the plasma core for a steady-state fusion reactor. To accomplish this the authors must develop steady-state operating scenarios at high beta for high fusion power density, low auxiliary power requirements (Q{sub CD} {ge} 25, where Q{sub CD} {triple_bond}P fusion/P{sub CD} and P{sub DC} is the power required for sustaining the plasma current) for low recirculating power requirements, and at moderate safety factor (q{sub {psi}} {le} 4.5) to minimize the cost for the tokamak core of a steady-state demonstration power reactor based on the operating modes demonstrated in ITER. The key to achieving steady-state operation at high fusion power in ITER will be the development of operating scenarios with very high bootstrap current fractions (f{sub BS} {ge} 90%) in which the radial profile of the bootstrap current density is well aligned with that of the total plasma current density, and for which the MHD {beta}-limit exceeds {beta}{sub n}{sup *} = 0.05 T{minus}m/MA. They are in the process of developing such operating modes for ITER. In {section}1 they propose two advanced steady-state operating points; a preliminary operating point that was the basis for the MHD studies reportedmore » in {section}2, and a second operating point that has been optimized based on the authors studies to date. In {section}2 they present calculations indicating that the initial operating point is stable to MHD ballooning and low-n kink modes (with a conducting wall at r = 1.25a) up to {beta}{sub n}{sup *} {approx} 6 {times} 10{sup {minus}2} T {minus} m/MA. In {section}3 they present a free-boundary MHD equilibrium, and show that advanced steady-state operating modes are compatible with the ITER poloidal field system and diverter.« less

A general theory for the stability of collision-less drift-wave eigenmodes in sheared slab magnetic fields is developed using the S-matrix technique. The eigenmodes are described with the integral formulation which fully takes into account the non-local effects of finite ion gyro-orbits. The universal eigenmode is then shown to be absolutely stable for arbitrary radial wavelengths.

A useful model for calculating the variation in the electron density, ion density, and ambipolar potential along magnetic field lines in the thermal barrier cell of a tandem mirror is presented.

In a recent GA report Ohkawa describes a novel electron cyclotron current-drive (ECCD) scheme. Ohkawa finds a net toroidal plasma current driven by ''up-down'' asymmetries in the electron pressure anisotropy, i.e., differences in p/sub perpendicular/ - p/sub parallel/ evaluated at the same absolute value of B between the top and bottom half of the poloidal cross-section. Such up-down asymmetries are associated with the s-dependent, first order in nu/..omega../sub b/ part of the electron distribution function (s is distance along a magnetic field line). The current-drive efficiency estimated by Ohkawa is competitive with other rf current-drive schemes. Ohkawa's scheme is attractive because it appears that this scheme can produce an rf-driven current even when the electron-cyclotron power is dissipated on trapped electrons; and the scheme requires no selectivity in the sign of the parallel velocity of the electrons heated by the electron cyclotron wave. In sections I through III of this memo we analyze the current-drive calculation presented by Ohkawa. We conclude that, in the limit of long mean-free-path appropriate to current tokamak experiments and tokamak reactors, the current Ohkawa attempts to compute from a fluid model is a neoclassical correction to the Fisch-Boozer current. Neoclassical effects that give rise tomore » corrections of this sort were first pointed out by Ohkawa in an earlier paper on ECH current drive. These neoclassical effects (which are associated with magnetic field variations and trapped particles) have been treated more accurately by using a kinetic rather than fluid theory in several recent papers. They are important because they can reduce the ECCD efficiency below the level computed by Fisch and Boozer.« less