Ion focus via microchannels in spherical inertial-electrostatic confinement and its pulsed experiment results

Summary form only given, as follows. Spherical inertial-electrostatic confinement fusion (IEC) uses spherical electric potential for accelerating and confining ion particles for nuclear fusion reactions. The U. of Il. device consists of two spherical concentric electrodes. The vacuum vessel wall serves as the outer electrode, and the inner electrode is a 85% transparent cathode-grid which is used to accelerate ions extracted from a plasma discharge formed between the wall and grid. Current experiments at the U. of Il. Measured the confining potential well while steady-state D-D fusion reaction rates of 10/sup 6/ reactions/sec have been achieved. At this level, the device already offers an attractive fusion neutron source for diagnostic applications. The current research described here is intended to increase the source strength, hence provide opportunity for new applications. To further increase the neutron yield, theoretical investigations have indicated a nonlinear neutron yield scaling at high current. Unfortunately, electrode heating has limited the current to only 10´s mA in steady-state operation. Pulsed experiments are now being explored to increase the current to higher levels while maintaining an average input power compatible with grid heating. In the paper, we describe the high current pulsed experiment results combined with the effect of microchannels on ion focusing. The implications of this results for higher power-density experiments are also presented.