PROGRESS IN THE UNDERSTANDING OF GRIDDED INERTIAL ELECTROSTATIC CONFINEMENT DEVICES AT THE UNIVERSITY OF WISCONSIN

摘要

For nearly two decades, as many as 4 Inertial Electrostatic Confinement (IEC) devices have been operated simultaneously at the University of Wisconsin-Madison. Over that time period we have learned that the early perceptions of how IEC devices operate are quite different from the actual performance in the Laboratory. Over the past 2 years we have gained even more understanding of IEC physics and technology. Experimental measurements and theoretical improvements have better characterized both the negative ions that contribute up to similar to 10% of the fusion rate in some cases and the neutral energy distributions in IEC devices at moderate pressure (0.07-0.7 Pa approximate to 0.5-5 mTorr). We also now understand more of why operation with helium plasmas has such a detrimental effect on high voltage performance of the traditional tungsten alloy grid wires. Most of the previous IEC work had been confined to < 100 kV with short operation times up to 150 kV. We have recently expanded our operating regime to approximate to 200 kV anode-cathode potential difference, which is, to our knowledge, the highest-voltage IEC operation reported in the worldwide IEC literature. Several design modifications were required to achieve steady-state operation at these high voltages and some are described in this article.