High-beta, hot-electron plasmas have been produced by electron-cyclotron heating in the SM-1 axisymmetric mirror using closely-spaced multiple frequencies. The relativistic electrons produce annular distributions (ELMO rings) with as much as ten times more stored energy than with single-frequency heating. While larger frequency separations (Δf/f∼0.1) provide some control of the ring size, the dominant effects are associated with an improvement in heating efficiency which persists to very small frequency separations (Δf/f∼10−3). Details of the reconstruction of the ring distribution (both in steady state and during build-up), the influence of multiple frequency heating on fluctuations, axial electron losses, and a scaling of these effects with power are presented.
The neutron activation cross sections near 25 kev have been measured for about 50 nuclei. Gamma-ray scintillation spectrometers with known efficiency were used to compare the radioactivities produced by the several nuclei with I 128 . This gave a significant increase in sensitivity and precision over direct beta-counting methods in many cases. Absolute standardization was obtained through scintillation-beta-counting the I 128 in Nal(Tl) crystals irradiated with a neutron source calibrated by the manganese bath technique.
The DCX-2 is a large, complex experimental apparatus. Its aim is the generation of a hot, dense plasma by the injection and dissociation of 600-kev hydrogen molecular ions in a magnetic-mirror field. For facilitating this process, the molecular ions are given a long path in the machine, and the ion-pumping action of the plasma is used to maintain the vacuum. The major component systems of the apparatus are the ion source and accelerator, high-voltage power supply, magnet system, beam-injection duct, vacuum system, and dissociating arc. This report describes the design, construction, and performance of each component system, the constructional features not peculiar to any one component, and the instruments and techniques available for plasma study.
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