Fast wave heating at the second, third and fourth harmonics of the ion cyclotron resonance, and slow wave heating at the fundamental in a single ion species hydrogen plasma, are found to be in gQod agreement with warm plasma theory at rf power levels 5130 kW. Ion heating is negligible off an eigenmode. Ion body temperatures are more than doubled to 75 eV from the 35 eV ohmically heated case with tails comprising 8% of the plasma at 320 eV. No deleterious effects except a nondisruptive 10% shortening of the discharge length caused by impurity influx are noted. A passive mode tracking technique allows =40% increase in power deposition in a passing eigenmode over that of a fixed frequency rf source. Ion temperatures are limited by charge exchange due to the <50eV central temperature and the small 13 cm radius current channel.

Cold, flowing hydrogen and helium ions axe observed with the retaxding ion mass spectrometer on Dynamics Explorer 1 in the dayside magnetosphere at subauxoral latitudes at 4500-km altitude. These ions show a marked flux asymmetry with respect to the relative wind direction. The observed data can be effectively modeled as drifting MaxwellJan distributions pertuxbed by a fixst-order Spitzer-I-i'grm heat flux distribution function. At high values of L, •14, both species are supersonic, and the shape and direction of the asymmetry are consistent with the presence of an upwaxd heat flux. As L dec•eases to ø"6, both species evolve smoothly into waxmet, subsonic upwaxd flows with downwaxd heat fluxes. In the subsonic cases this implies a significant heat souxce at higher altitudes. These results are found to match theoretical predictions for the polar wind. However, in both cases, in order to match the observed depaxtuxes from a simple drifting Maxwellian, the mean free path must be as much as one-half the thermal gradient scale length. This strongly suggests that collisionless effects axe stronger than predicted and dominate the heat transport throughout the entire transition from supersonic to subsonic flow. These observations demonstrate a capability to observe transport effects in plasmas as higher moments of the distribution function, making possible compaxisons with hydrodynamic theories which have until now been experimentally unverified. ionized gas, Phys. Rev., 89, 977, 1953. Stone, N.H., The aerodynamics of bodies in a taxifled ionized gas with applications to spacecraft envixonmental dynamics, NASA Tech. Pap., 1931, 1981.

The.latest in a series of internal-ring devices, called Tokapole II, has recently begun operation at the University of Wisconsin. Its purpose is to permit the study of the production and confinement of hot, dense plasmas in either a toroidal-octupole (with or without toroidal field) or a tokamak with a four-node poloidal divertor. The characteristics of the device and the results of its initial operation are described here. Quantitative measurements of Impurity concentration and radiated power have been made. Poloidal divertor equilibria of square and dee shapes have been produced, and an axisymmetric instability has been observed with the inverse dee. Electron cyclotron resonance heating is used to initiate the breakdown near the axis and to control the initial influx of impurities. A 2-MW RF source at the second harmonic of the ion cyclotron frequency is available and has been used to double the ion temperature when operated at low power with an unoptimized antenna. Initial results of operation as a pure octupole with poloidal Ohmic heating suggest a tokamak-like scaling of density (n <* B p) and confinement time (T.<* n).

A system has been developed specifically for the calibration and development of thermal ion instrumentation.The system is optimized to provide an extended beam (approximately 80 cm ) with usable current rates/ -1 pA/cm , at beam energies as low as 1 eV, with much higher values available with increasing energy. The beam energy spread is typically less that 2 eV/charge, and the average angular divergence is approximately 2.5 deg. A tandem electrostatic and variable geometry magnetic mirror configuration within the ion source optimizes the use of the ionizing electrons, thus decreasing the gas and non-thermal electron throughput to the instrument chamber while improving the current density uniformity.The system is integrated under microcomputer control to allow automatic control and monitoring of the beam energy and composition and the mass-and angle-dependent response of the instrument under test.The data can be transmitted in nearly real-time to the interested investigators for comparison with expected results over existing computer networks. The system is pumped by a combination of carbon vane and cryogenic sorption roughing pumps and ion and liquid helium operating pumps.This allows testing and final calibration of flight instrumentation in an ultraclean environment. KEY WORDS

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