Temperature and Power Measurements in a Plasma Heated by Absorption of Ion Cyclotron Waves

Abstract

A plasma in a magnetic mirror field is heated by means of an induction coil which generates plasma waves at a frequency near the gyrofrequency of the ions. Several hundred kilowatts of power are transmitted to the plasma. Ion energies in the neighborhood of 1 keV are observed in a small volume within the plasma. These energies are believed to be associated with ions trapped within a small magnetic mirror region following their acceleration by ion cyclotron damping of the waves. In a deuterium plasma production of neutrons is observed in association with these trapped ions. Ion energies of 200–300 eV are found throughout the total 10‐liter plasma volume. The electron temperature is approximately 10 eV. Energy is lost from the plasma in times ranging from 30–50 μsec. This loss rate appears to result from particle losses as well as radiation from impurities. To explain the loss of energy it is not necessary to invoke an instability mechanism.