Heated Langmuir probe measurements of reactive directcurrent magnetron plasmasThe theory for an asymmetric Langmuir probe is developed for the case of a collisionless streaming high-density (a.>Rp>30~) plasma with T.
A hollow cathode discharge (HCD) is described that produces a highly ionized steady-state plasma (ne≈1013−1014/cm3) at a temperature 1–10 eV, in a volume as large as 104 cm3, with background neutral gas density ≈1013/cm3. The HCD is generated by the prescription: gas flow (H2, He, A, or N2) 0.05–2 cc STP/sec through a refractory metal hollow cathode tube into a vacuum; any anode; 20–200 V dc applied. An axial induction 100–1000 G is used to collimate the discharge and to aid in starting by rf excitation. The HCD runs from the cathode interior, deep enough that p0d≈1 cm×mm Hg. Current range is 2.0–300 A. Various electrode configurations and a wide range of operating parameters have been studied. The external plasma density and temperature were measured by Langmuir probes. A discussion is given of the confinement mechanism and of the energy balance, both in the external plasma and in the region of the cathode itself.
The achievement of controlled fusion will make available excess neutrons which can be used in various ways in combined fission-fusion power cycles. The various schemes are here classified as hybrid–in which heavy-element fission occurs in the fusion blanket; symbiotic–in which fissile material is bred in the absence of fission events; and augean–in which the neutron surplus is used to transmute fission reactor waste products. The earliest work in this field, unpublished and originally classified secret, is reviewed. Recent studies of hybrid systems based on subcritical thermal and sub-critical fast-fission blankets are described in detail. An analysis of symbiosis based on the Th-U fuel cycle is summarized. The conditions required for high-level waste transmutation are presented; Augean systems seem best suited to actinide waste burning. It is concluded that basic physics of various fission-fusion systems has been surveyed but the engineering and economic aspects of combined systems have been largely ignored. It remains to be shown whether fission-fusion systems will prove superior to alternative methods of accomplishing the same ends.
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