摘要:

In support of the international collaborative effort into fusion research, work has begun to re-commission the Deuterium Negative Ion Source Experiment (DENISE) at Dublin City University (DCU). Modifications to the original system are nearing completion. The major goal of these modifications is easier access to both the ion source and the extraction region for diagnostic systems. A new source chamber has been installed. It can be used with both standard Langmuir probes, and a new laser photo-detachment probe currently under construction. The source chamber allows operation in any one of three modes: filament driven, CW RF driven, or Pulsed RF driven (up to 3 kW of 13.5 MHz RF at 250 Hz). A PC computer control system based on LabView™ is nearing completion and is intended for both system control and data logging. An investigation into the production and extraction ofH−ions has begun. Langmuir probe data has been collected at pressures from 5–200 mTorr, for CW RF powers between 25 and 600 W, and for 3 radial probe positions. This paper will present the current status of DENISE and the future plans for this versatile source. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56344

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In a collaboration with CEA Cadarache, IPP is presently developing an rf source, in which the production of negative ions(H−/D−)is being investigated. It utilizes PINI-size rf sources with an external antenna and for the first step a small size extraction system with 48 cm2net extraction area. First results from BATMAN (BavarianT_estMachineforN_egativeIons) show (without Cs) a linear dependence of the negative ion yield with rf power, without any sign of saturation. At elevated pressure (1.6 Pa) a current density of 4.5 mA/cm2H−(without Cs) has been found so far. At medium pressure (0.6 Pa) the current density is lower by approx. a factor of 5, but preliminary results with Cesium injection show a relative increase by almost the same factor in this pressure range. Langmuir probe measurements indicate an electron temperatureTe>2&hthinsp;eVclose to the plasma grid with a moderate magnetic filter (700 Gcm). Attempts to improve the performance by using different magnetic configurations and different wall materials are under way. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56364

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

This paper describes the mechanism of efficientH−production in a high-density hydrogen plasma produced by helicon wave discharge. AnH−source using helicon wave discharge has been developed. Spatial and temporal variations ofH−density in the helicon plasma were measured by laser photodetachment technique. A steep increase inH−density was observed in the afterglow. TheH−ions were efficiently produced for the first 20&mgr;s after the termination of the discharge and mainly lost by mutual neutralization with positive ions. In the outer region of the plasma column, 20&percent; of the negatively charged particles wereH−ions. In the region ofTe=1.5−2&hthinsp;eV,the effective attachment rate coefficient defined as the average value for hydrogen molecules of all energy levels was evaluated to be0.5−1.3×10−11&hthinsp;cm3/s,of which the value is 3-order higher than that for attachment to thev=0level of the ground state molecules. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56365

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

For the European Spallation Source (ESS), a volume source based on the HIEFS (high efficiency source) is being developed. The source will be optimized to produce high current densities in pulsed operation. A pulse generator delivering 1 to 1.5 ms pulses was installed. Furthermore, cesium was supplied to the plasma generator from an external oven. The cesium injection was optimized for a lowe/H−ratio and a high current. We obtained a current density of 70 mA/cm2. This way, with an aperture radius of 4.25 mm, anH−current of 40 mA was extracted at an extraction voltage of 22 kV. After a description of the source and the experimental setup, measurements of the beam current density and thee/H−ratio will be presented in this paper. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56345

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The results of theoretical and experimental studies of physical processes in the source of hydrogen negative ions are presented. The source is based on reflective discharge with incandescent cathode andH−ions extraction across magnetic field. Calculations of gas discharge plasma parameters for given current and energy of electrons emitted from the cathode are performed in theoretical part of the proceeding. Plasma parameters, includingH−ions concentration, are determined on a basis of Boltzman equation solution taking into consideration principal collision reactions in a volume and at a surface of the discharge chamber. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56346

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In recent times, special merits of negative ion beams have been recognized in the context of novel materials science applications, and there is a plenty of room for further growth of the field. Various kinds of negative ion sources are currently available. Compact surface-plasma type sources, namely, Penning, planotron and semi-planotron sources, are discussed with special emphasis on the merits of these sources for applications in the area of microlithography, ion microscopy, and surface modifications. The potential of these sources for high-current applications, such as spallation neutron source, is also discussed. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56366

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Production and control of electron cyclotron resonance (ECR) plasma for volume sources have been studied and preliminary results are presented. Effects of magnetic filter in ECR plasmas are discussed by comparing with ones in DC plasmas. Electron energy distribution in DC plasma is well controlled with the use of the magnetic filter. In ECR plasmas, however, electron cooling due to the magnetic filter in the extraction region is not so effective as ones in DC plasmas. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56347

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Since 1994 an RF drivenH−volume source has been operated in the DESY source test stand. In 1995 the source was operated successfully as injector for LINAC III and DESY III. The source is planned as a Cs free low emittance replacement of the magnetron.H−sources for HERA have to run for long uninterrupted periods (300 days) with a low duty factor (0.01&percent;) and a high reliability. NewAl2O3ceramic antenna constructions are presented in order to improve the antenna lifetime. Recent measurements have demonstratedH−currents of up to 80mA in our uncesiated volume source. This was possible due to a negative bias of the collar, a tantalum coating on the collar inside and an optimization of collar and extraction geometry. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56367

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A multi-stage, multi-aperture electrostatic accelerator for hydrogen negative ions has being developed to demonstrate 1 MeV, ampere-class H- beam acceleration. The accelerator consists of an extractor and a five stage accelerator supported and insulated by fiber reinforced plastic (FRP) cylinders. Forty nine apertures were drilled on each electrode. Diameter of the aperture is 14 mm in the extractor and 16 mm in the accelerator. Whole dimensions of the accelerator are 2 m in diameter and 2.5 m in height. The accelerator was conditioned up to a voltage of 920 kV without beam. A highest beam energy of 868 keV with an acceleration current of 19 mA for a duration of 1 s was obtained from nine apertures. An optimum beam perveance agreed well to the beam trajectory simulation. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56348

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Injection of intense neutral beams based on the neutralisation of negative deuterium ions up to energies of 1 MeV is an important option for plasma heating and non-inductive current drive in future thermonuclear fusion machines. The objective of the SINGAP experiment is to demonstrate the acceleration of 100 mA ofD−to 1 MeV in an electrostatic accelerator concept which is substantially simpler than the multi-aperture, multi-grid accelerator system foreseen for the ITER neutral beam injectors. Voltage holding without beam has been demonstrated at above 1 MV after only 35 min of integrated voltage on-time.H−beams have been produced up to 860 kV, 40 mA in 1 s pulses and without caesium seeding of the ion source. With caesium admixture,D−beams of 105 mA have been accelerated to 630 keV for 1 s. These results were obtained at energies lower than 700 keV because of the bushing deterioration. The measurements of the beam profiles are in good agreement with the results obtained from 3D trajectory calculations. ©1998 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.56368

出版商:AIP    

年代:1998

数据来源: AIP