No abstract available

[en] All large tokamak fusion experiments today use auxiliary heating by multi-megawatt beams of neutral isotopes of hydrogen injected with energies in the neighborhood of 100 keV per atom. This requires reliable operation of large ion sources, each delivering many tens of amperes of protons or deuterons, and soon even tritons. For meaningful experiments these sources must operate with pulse durations measured in seconds, although the duty factor may still be small. It is remarkable that the successful sources developed in Europe, Japan and the US are all very similar in basic design: the plasma is produced by diffuse low-pressure high-current discharges in magnetic multipole ''buckets'' was distributed thermionically emitting cathodes. This paper briefly reviews the principal considerations and the basic physics of these sources, and summarizes the collective experience to date and describes the impressive recent performance of the US Common Long Pulse Source, as a specific example. 20 refs., 6 figs., 2 tabs

[en] Most of the large magnetic confinement experiments today and in the near future use high-power neutral-beam injectors to heat the plasma. This review briefly describes this remarkable technique and summarizes recent results as well as near term expectations. Progress has been so encouraging that it seems probable that tokamaks will achieve scientific breakeven before 1990

[en] After 30 years of research and development in many countries, the magnetic confinement fusion experiments finally seem to be getting close to the original first goal: the point of ''scientific break-even.'' Plans are being made for a generation of experiments and tests with actual controlled thermonuclear fusion conditions. Therefore, engineers and material scientists are hard at work to develop the required technology. In this paper the principal elements of a generic fusion reactor are described briefly to introduce the reader to the nature of the problems at hand. The main portion of the presentation summarizes the recent advances made in this field and discusses the major issues that still need to be addressed in regard to materials and technology for fusion power. Specific examples are the problems of the first wall and other components that come into direct contact with the plasma, where both lifetime and plasma contamination are matters of concern. Equally challenging are the demands on structural materials and on the magnetic-field coils, particularly in connection with the neutron-radiation environment of fusion reactors. Finally, the role of ceramics must be considered, both for insulators and for fuel breeding purposes. It is evident that we still have a formidable task before us, but at this point none of the problems seem to be insoluble. 17 refs., 3 figs

No abstract available

[en] The work reported herein was aimed at investigating and understanding the Tormac Concept of fusion containment. Tormac (torodial magnetic cusp) is a stuffed, torodially symmetric line cusp. As a cusp, it possesses an absolute minimum-B with the advantage that it is MHD stable at high beta. For a fusion reactor, the economies and simplifications that derive from this advantage, and other Tormac characteristics, are many. The experimental program has been carried out at Lawrence Berkeley Laboratory using three devices: Tormac IV, Tormac V, and the Puffer Experiment. In Tormac IV, a high density, high beta plasma has been studied in a bicusp equilibrium. Tormac V has been used to study the start-up of Tormac. These studies have highlighted the problem of converting a Tokamak-like discharge to an absolute minimum-B geometry. The Puffer Experiment has developed a new type of plasma gun, which is used to inject a Tokamak-like plasma configuration into a Tormac geometry. The Puffer Experiment offers a natural way for Tormac start-up, and seems to solve the problems indicated by the Tormac V experiment

No abstract available

[en] In recent years, H^- ions have been found important applications in high energy accelerators and in neutral beam heating of fusion plasmas. There are different techniques for producing the H^- or D^- ions. The most attractive scheme is the direct extraction of H^- ions from a hydrogen discharge. This technique requires no cesium and it utilizes the existing large area positive ion source technology. This paper investigates this techniques. 14 refs

[en] A method of generating a high purity (at least 98%) N⁺ ion beam using a multicusp ion source having a chamber formed by a cylindrical chamber wall surrounded by a plurality of magnets, a filament centrally disposed in said chamber, a plasma electrode having an extraction orifice at one end of the chamber, a magnetic filter having two parallel magnets spaced from said plasma electrode and dividing the chamber into arc discharge and extraction regions. The method includes ionizing nitrogen gas in the arc discharge region of the chamber, maintaining the chamber wall at a positive voltage relative to the filament and at a magnitude for an optimum percentage of N⁺ ions in the extracted ion beams, disposing a hot liner within the chamber and near the chamber wall to limit recombination of N⁺ ions into the N₂⁺ ions, spacing the magnets of the magnetic filter from each other for optimum percentage of N³ ions in the extracted ion beams, and maintaining a relatively low pressure downstream of the extraction orifice and of a magnitude (preferably within the range of 3-8x10^-4 torr) for an optimum percentage of N⁺ ions in the extracted ion beam

[en] H/sup /minus// and D/sup /minus// ions have useful applications in high-energy accelerators and in neutral beam heating, or for current drive of fusion plasmas. Among the different techniques for producing H/sup /minus// ions, direct extraction from a hydrogen discharge is the most attractive. This method requires no cesium and the H/sup /minus// ions generated by volume processes have lower average energy than those formed by surface conversion or by charge exchange processes. For this reason, intensive research and development of volume H/sup /minus// sources are now being conducted at various accelerator and fusion laboratories