An engineering study of r.f. heating of fusion reactors is described. The frequency range considered is below 100 MHz. Special consideration is given to r.f. structures located between the reactor wall and the plasma in the main fusion region. Possible arcing problems in this region are discussed and it is found that they may not be too serious for neutral pressures below 10−4 torr. It is proposed to feed the r.f. through a slanted vacuum port in order to reduce port area and to protect the voltage insulator from radiation and temperature damage. The cooling of an r.f. coil structure is considered in detail. It is proposed to use a split r.f. coil composed of heat pipes to carry the heat away. Curves are presented which give the maximum r.f. on-time for various coil currents, frequencies, and coil sizes before the coil surface reaches melting temperature. Other coupling schemes involving the use of the vacuum wall as a r.f. structure or locating a wave launcher in the high-field region of a mirror reactor are discussed. In the case of a mirror reactor it is found that this last scheme may be quite attractive since unidirectional couplers can be made and experimental results indicate that the wave reflections may not be too serious in the severe-density and field gradients. This scheme also offers a possible way of launching, for instance, ion-cyclotron waves into very dense plasmas. It is concluded that the engineering problems of fusion-reactor-r. f. heating, albeit formidable, are not impossible.

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An experimental study has shown that dc arc welding generators can be used satisfactorily as an inexpensive power source for large magnet systems. A 120 Hz load current ripple of only 0.05% rms was measured at one-half load and decreased for heavier loads. Random low frequency current fluctuations of ⪞3% peak-to-peak were detected but were reduced to ⪝0.5% peak-to-peak with a feedback technique.

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A high current, battery-operated power supply with power control through an on-off fast switch Rev.