Description: In a previous report the adaptation of Stix's ion-cyclotron-wave-heating scheme to the mirror geometry was suggested. An experiment along these lines has been conducted for the past year by E. Chambers, using a tubular P.I.G discharge to provide the basic plasma. The Chambers experiment has been eminently successful in demonstrating the transfer of rf power along the P.I.G. (as along a co-axial conductor), and the resultant acceleration of ions. The power transfer is evident from the predominantly resistive rf impedance of the P.I.G. (1 - 10 ohms), the production of intense luminosity outside the dc P.I.G channel when the rf is turned on, and by the observation large signals with magnetic pick-up loops. The ion heating is demonstrated by direct measurement of ion current on a probe some centimeters outside the P.I.G., and by the observation of energetic charge-exchange neutrals. At the same time, the characteristic features of heating by ion-cyclotron-waves, as described by Stix, are only partly in evidence. The visible broadening of the P.I.G. channel and such fast-ion phenomena as neutral emission do seem to be maximal near the expected cyclotron resonance point. However, the rf impedance is anomalous both in magnitude and parameter dependence, and there are many other anti-theoretical phenomena, such as the obvious propagation of substantial power all along the P.I.G., even under conditions (low magnetic field) when ion-cyclotron waves should be cut off near the input electrode structure. Thus it appears that, while the desired ends are very satisfactorily achieved by the experiment, the working principle is not that originally intended.
Date: April 6, 1960
Creator: Furth, Harold P.
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