摘要:

Review of the Kurchatov Institute program on negative ion beam is given. Main tasks of the program: (i) Negative ion sources development, discharge plasma H−1(D−) sources with and withoutCs; investigation of alternative possibilities; rf‐driven discharges for negative ion sources; (ii) Negative ion accelerators, ES acceleration. Numerical simulations, preliminary experiments, proof‐of‐principle test stand construction (MIN‐2). rf acceleration (preliminary proposal); (iii) H−(D−) beam neutralizers, gas neutralizer (construction for MIN‐2), plasma neutralizer (designing and modeling), laser neutralizer (preliminary investigation and modeling); (iv) ITER NB system designing; (v) ITER NBI test stand designing (STIN project).

ISSN:0094-243X    

DOI:10.1063/1.44831

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The main design points of the European Community proposal for an injector module suitable for ITER are described. Such a module has to deliver 8.3 MW of 1.3 MeV D° to the plasma for very long pulses, up to 2 weeks in duration. The design takes as starting assumptions the use of a ‘‘pure volume’’ D−source, an electrostatic accelerator, and a D2gas neutralizer. Subdivision of the neutralizer reduces the total gas flow, which, combined with differential pumping at the source, minimizes the required cyro pump speed. The combined ‘in line’ electrostatic residual ion deflector and dump are also subdivided, which reduces the required deflection angle and electric field. The expected power densities on all components except the beamline calorimeter are relatively low, permitting the use of conventional cooling technology, giving good inherent safety and long component lifetime. The beamline calorimeter, where the expected power density is <7 MW/m2, is not exposed continuously to the beam, and such power densities are readily handled by a variety of technologies.

ISSN:0094-243X    

DOI:10.1063/1.44832

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A negative‐ion‐based NBI test‐stand has been constructed in Toki site of National Institute for Fusion Science (NIFS). This Toki test‐stand has facilities to produce 2.5 MW neutral beam power with the energy of 125 keV for hydrogen and 250 keV for deuterium, which is utilized for developing a unit of neutral beam injection (NBI) system for Large Helical Device (LHD). All components of the Toki test‐stand are installed on the basis of conceptual design of the LHD‐NBI system. Development of a high‐current negative ion source with vacuum‐immersed structure is one of the main objectives of the test‐stand, as well as transport of a high‐energy beam with a small divergence angle. It is also an important subject to test all of hardware components such as beam dumps and cryo‐pumps. Experiments started in July.

ISSN:0094-243X    

DOI:10.1063/1.44833

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Formation of negative ion beams is considered with respect to the project of a multi‐channel radio‐frequency injector of D0(H0) energetic atoms for ITER.1Experimental and theoretical studies are carried out on formation of a high‐current beam in a single channel of the preinjector which consist of a surface‐plasma source and a 90°‐bend magnet. Gas compensation of the beam space charge and the magnet carrying capacity are investigated and the beam phase characteristics are measured at the peak current of 200 mA at the forming device outlet. Numerical simulations are performed for a concept of a direct beam forming system with the injection energy of 100 keV. Beams are focused by means of magnetic quadrupole lenses and gas fillings are done in order to compensate the high‐current beam space charge. The formation device parameters are optimized in order to match the beam emittance with the quarter‐wavelength resonant accelerator acceptance.

ISSN:0094-243X    

DOI:10.1063/1.44801

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A ‘‘scalable model’’ test bed using a reduced version of an ITER beam source has to allow tests of not only the source, but all the important aspects of the system at levels that make scaling to a full injector credible. The performance required from such a test bed has been carefully considered, and the European Community (EC) version of a test bed and beam source is described. The ‘‘engineering’’ of this design has been entered into in sufficient depth to allow all the problem areas to be identified, and solutions proposed.

ISSN:0094-243X    

DOI:10.1063/1.44802

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Energy recovery experiments have been conducted for the first time with a negative ion based neutral beam injector. A new type of energy recovery system was utilized, which: (i) separates electrostatically the neutrals and charged components of the beam at the exit of the neutralizer; (ii) decelerates the residual unneutralized negative ions; (iii) prevents secondary emission of electrons from the negative ion collector by means of electrostatic trapping. With 102 keV, 1.2 A D−beams, the residual negative ions have been decelerated with high efficiency down to 8 keV. By taking into account the power consumption of the electrostatic deflector, the recovery efficiency of the residual negative ion beam power was as good as 81%, at a background gas operating pressure around 10−3Pa.

ISSN:0094-243X    

DOI:10.1063/1.44803

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Theoretical investigations are reviewed concerning interactions of negative ion beams with rarified plasma oscillations directly behind the ion source, as well as with a dense plasma in a neutralizer. Effects of beam‐plasma instabilities on transportation of D−(H−) ions in an injector are studied. It is shown that nonlinear collective heating essentially influences phase characteristics of a slow ion beam during its formation and entering a rf accelerator. In the neutralizer, the beam emittance does not grow due to amplitude confinement of plasma oscillations at a low level as a result of capturing the beam electron component. A possibility of beam compression under the action of fast oscillating fields of electron surface plasma waves is considered.

ISSN:0094-243X    

DOI:10.1063/1.44805

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

It is proposed to conduct on the Cadarache neutral beam test bed an experiment with the following characteristics: 1 MeV, 0.1 A, D−, long pulses (several seconds). This experiment will deal with several ITER neutral beam relevant subjects, which are critical and still not (or poorly) explored: (i) development of scalable high‐energy (up to 1 MeV) D−accelerator concepts, with current densities in the 10 mA/cm2range, adequate optical quality and suppression of stray particles (electrons, etc.); a simplified concept of accelerator, SINGAP, will be compared to a multi‐hole multi‐gap accelerator; (ii) study of breakdowns in the presence of the beam with a vacuum insulated beamline and effects of a large stored electrostatic energy released during breakdowns (100 Joules range); (iii) development of critical HV devices (large insulator for bushing; decoupling devices for the external stray capacitances; fast protection systems in case of breakdowns). If this proposal is accepted by the European Community beginning of 1993, the experiments could start by mid‐1994.

ISSN:0094-243X    

DOI:10.1063/1.44806

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

At this meeting, we had many interesting talks. The topics include: the basic phenomena in sources on surface production; volume production sources and basic phenomena; temporal filter concept; the effect of filament number, position and material; the effect of introducing cesium; diagnostics; extraction and acceleration of beams; modeling; volume scaling laws; neutralizers; negative ion sources being used on new accelerators, etc. (AIP)

ISSN:0094-243X    

DOI:10.1063/1.44807

出版商:AIP    

年代:1992

数据来源: AIP