摘要:

Negative hydrogen ions are extracted from a sheet plasma and extracted H−currents are optimized for several parameters; a location of the extraction electrodes, a bias voltage, a filling gas pressure and a discharge current. There is an optimum position of the electrodes near the plasma periphery and an optimum pressure for the H−production. The profiles of the electron density and temperature are measured and the relation between the profiles and the H−yield is investigated. It is found that the H−yield is optimized when the electron temperature in front of the extraction grids decreases below 1 eV and that this optimum condition can be achieved by changing the position of the electrodes and/or by changing the filling gas pressure.

ISSN:0094-243X    

DOI:10.1063/1.39592

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Experiments performed in a volume production negative ion source show that the use of a tent or supercusp magnetic filter leads to a more uniform plasma at the normal extraction plane than that obtained with a dipole filter.For the tent filter geometry the extracted negative ion current density, increased as the accelerator was moved into the source to a maximum value of about 30% greater than that measured at the normal extraction plane.There is evidence that the primary electrons were well confined by the magnetic on the walls of the source, but that significant numbers of positive ions were able to escape from the source by cross‐field diffusion, at pressures in excess of 7 mTorr.

ISSN:0094-243X    

DOI:10.1063/1.39593

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

This paper presents the results of experimental studies on a number of different ‘‘current carrying wire’’ type first grid electron suppressors: or ‘‘inserts’’, as they shall be called throughout this paper. Extracted negative ion currents are compared for the different inserts over a range of field strengths. Currents are also compared to those extracted with no suppressor present. An attempt is made to relate the negative ion currents obtained for each insert, with field depth and uniformity. Results are presented on the extraction of negative ions with an insert operating some distance into the source. The insert is also tested with a dipole rather than tent field used to separate the driver and extraction regions of the source.

ISSN:0094-243X    

DOI:10.1063/1.39594

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

This paper reports tests of an electron suppressor, for volume negative ion sources with variable electric and magnetic fields. The experiments have been carried out with a source and accelerator operating d.c. and with an extraction aperture of 16 mm diameter. The results are compared to those obtained with a permanent magnet suppressor and to a theoretical model of the transport of electrons by diffusion across the magnetic field.

ISSN:0094-243X    

DOI:10.1063/1.39595

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We report experiments of extracting negative and positive ions and electrons from a multicusp volume ion source. The effect of a transverse magnetic field in front of the plasma electrode is reported for the three extracted species when the bias of the plasma electrode is changed. Also the effect of the discharge current and of the pressure are reported. The experiments indicate that the effect of the magnetic field is to enhance the negative ion current and to suppress a great part of electrons from the extracted current. An explanation based on electron behavior in the magnetic field is proposed.

ISSN:0094-243X    

DOI:10.1063/1.39596

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

By using a time‐resolved Langmuir probe method, the time dependent plasma parameters of a low frequency (<500 kHz) rf driven D2discharge have been measured. It is found that at certain times during the rf cycle, the electron temperatures measured are very low (0.2–0.8 eV). This suggests that rf driven discharges may be suitable as sources of negative ions.

ISSN:0094-243X    

DOI:10.1063/1.39597

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A negative hydrogen volume source, whose main feature is the plasma containment in a potential well produced by radiofrequency multipole, is under construction.In this paper the experimental set‐up and preliminary electrical measurements are presented.

ISSN:0094-243X    

DOI:10.1063/1.39598

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

This paper describes a large filtered multicusp H−ion source. The influence of a number of parameters on the yield characteristics of the H−source were investigated including pressure in discharge chamber, cathode−filter spacing and multicusp geometry. (AIP)

ISSN:0094-243X    

DOI:10.1063/1.39599

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The magnetic field of the BNL toroidal volume H−source1has been calculated using the code PANDIRA2for two different configurations. The first configuration was a set of concentric rings of permanent magnets. The second configuration was similar to the first, except that an axial magnet had been added to provide a dipole field on axis. Contour plots of the vector potential and total magnetic field have been provided for each case.

ISSN:0094-243X    

DOI:10.1063/1.39600

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

This paper is a progress report on the studies of the BNL volume H−ion source. We have measured the H−yield,IH−, and the ratioIe/IH−as function of the size of the extraction aperture, strength of the conical filter field, size and position of the filament, and of the phase of the filament heating current. The H−current density in the extraction aperture was lower for the largest aperture, while there was a broad maximum when the conical field varied. Position of the filament and the phase of the filament heating current are very important parameters.

ISSN:0094-243X    

DOI:10.1063/1.39601

出版商:AIP    

年代:1990

数据来源: AIP