摘要:

An RFQ has replaced the 750 keV Cockcroft‐Walton as the H−preinjector for the AGS. A magnetron surface‐plasma source with a circular aperture is used to produce 65–100 mA of H−at 35 keV with a discharge current of less than 20 A. The circular symmetry of the beam is maintained in the 2 m transport to the RFQ via the use of magnetic solenoids for focusing. Currents of up to 60 mA have been obtained out of the RFQ.

ISSN:0094-243X    

DOI:10.1063/1.39656

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A beam of energetic H−or D−ions is efficiently converted to the uncharged state upon impact on a dense plasma. Neutralization efficiencies of the emerging beam can exceed 80%. This paper reports on a design approach to a plasma‐stripping cell, illucidating several practical aspects. The plasma is formed by a low‐frequency (1.4 MHz), high‐power (20–60 kW) rf discharge in a multipole ring‐cusp magnetic field. A mild steel rectangular box is used as a low‐reluctance return path for the magnetic flux, a heat‐transfer medium, and mechanical support. The working gases used in these studies are H2, He, Ar, and Xe. The central density found in the resulting plasma ranged from about 1013to ≳1014cm−3with the heavier species exhibiting the higher densities. Test results performed over a pressure range of 2–10 mTorr are presented. The rf power required to achieve a given plasma density with this design should scale with the cell length for a given gas.Measurements of magnetic‐flux‐density components in the plasma cell volume occupied by the beam path yielded results that are in good agreement with previous calculations. A two‐axis Hall probe is used to measure the magnetic field in two planes, separated by a distance of 1 cm and extending 7 cm beyond the beam entrance, over one quadrant of the beam path. Using these measurements, we produce surface plots of the components and modulus of the magnetic flux density, as well as the projection of flux contours onto their respective planes. The magnitude of any magnetic‐field component is <15 G and also the modulus of B is <15 G in the path of the beam through the cell. The magnetic field at 0.5 cm from the internal copper wall measures ≳1.5 kG, while only 1.4 G is found at the same distance outside the box.

ISSN:0094-243X    

DOI:10.1063/1.39643

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Presented are results on the modelling of a cascaded arc. Under suitable conditions, the plasma effusing out of the arc has a high degree of ionization. It is proposed to use this arc as the plasma source of a plasma neutralizer in neutral beam injectors for fusion research. The neutralization of a D−beam results in the generation of an electron beam. The power in thise‐beam is too small to sustain the plasma in the neutralizer for the 1.3 MeV fusion beams.

ISSN:0094-243X    

DOI:10.1063/1.39644

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Scaling of velocity space relaxation rates, which affect the final temperature of a neutral beam, with ion charge state in plasma neutralizers is examined. Overall, this scaling indicates a substantial enhancement in emittance growth of the neutral beam with increase in the charge state of ions in plasma neutralizers.

ISSN:0094-243X    

DOI:10.1063/1.39645

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We examine the feasibility of creating an electric space‐charge field of order 109V/m using radial and axial focussing on a pulsed beam of 200 MeV H−ions. When a bunch of H−ions is focussed into a disc‐shaped concentration, the electric field is uniform and the electrons are shed abruptly, leaving a neutral beam of H0. Subsequent stripping of the H0discs by a carbon foil produces highly ordered oscillating plasma bunches which can act as an electrode‐less high gradient accelerator structure.

ISSN:0094-243X    

DOI:10.1063/1.39646

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

One of the possible applications for which negative ion based neutral beams might be used is for producing peaked density profiles in tokamaks through beam fuelling. This paper examines the implications of such beam usage upon the tritium throughput, and ways in which the required tritium inventory might be kept to a minimum.

ISSN:0094-243X    

DOI:10.1063/1.39648

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

High energy negative ion‐based neutral beam injection is a strong candidate for heating and non‐inductive current drive in tokamaks. Many of the equations related to the physics and engineering of this technique remain unanswered. In this paper, we consider the possibility of negative ion‐based neutral beam injection on DIII‐D. We establish the desired parameter space by examining physics trades. This is combined with potential design constraints and a survey of component technology options to establish an injector concept. Injector performance is estimated assuming particular component technologies, and concept flexibility with respect to incorporating alternate technologies is described.

ISSN:0094-243X    

DOI:10.1063/1.39649

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The present plans for the Compact Ignition Tokamak (CIT) call for the auxiliary heating to be done by RF techniques. However, Goldston has proposed that an alternative scenario might involve running TFTR type ‘‘supershot’’ plasmas with peaked density profiles. This would require central fuelling by deuterium and tritium beams. We have performed a conceptual study of a system to inject negative ion based 300 keV beams of D and T using the available port geometry. We report on the resulting conceptual design, the tritium usage during operation, and the implications for the test cell configuration. Work supported by U.S. DOE Contract Numbers DE‐AC02‐76CHO3073 and DE‐ACO3‐76SF00098.

ISSN:0094-243X    

DOI:10.1063/1.39650

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Three negative ion beam programs for nuclear fusion research are proposed at the Japan Atomic Energy Research Institute (JAERI): a 500 keV, 10 MW deuterium neutral beam injection (NBI) for heating and current drive in the JT‐60U tokamak, a 0.5/1 MeV, 50 MW deuterium beam injection for the Fusion Experimental Reactor (FER), and a 2 MeV, 20 mA lithium beam injection for ion temperature measurement in the JT‐60U. The 500 keV negative‐ion‐based NBI system for the JT‐60U will be developed in the first step, followed by the development of the reactor relevant 0.5/1 MeV NBI system. This two step development mitigates the risk in developing a MeV class NBI system.

ISSN:0094-243X    

DOI:10.1063/1.39651

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Concluding remarks

ISSN:0094-243X    

DOI:10.1063/1.39652

出版商:AIP    

年代:1990

数据来源: AIP