摘要:

This paper gives the results of numerical modeling of secondary particles fluxes within 1.3 MeV multi‐electrode electrostatic accelerator of D−ion beam, the distribution of power loads to the electrodes and ways of their reducing and increasing the accelerator power efficiency by using a combination of transverse magnetic fields.

ISSN:0094-243X    

DOI:10.1063/1.44837

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We present a design for the low‐energy H−injector. It is used in conjunction with a rf‐driven multicusp source and will deliver 30 mA of H−at 35 kV, at a pulse length of less than 1 msec to a RFQ downstream (used in the LINAC booster of the SSC, for example). It has several distinguishing features and meets the goal of having an outgoing beam free of electron contamination, with small radius, large convergent angle and small projectional emittance. The specific example presented meets all the requirements of the injector for SSC RFQ. However, the principle and method used should easily be adapted for the designs of injectors with similar requirements for other purposes.

ISSN:0094-243X    

DOI:10.1063/1.44821

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Studies of H−‐ion beam injector for a linear accelerator operating at a frequency of 433 MHz were carried out. The results are given. The injector is a system consisting of a Dudnikov’s source, bending magnet, and electrostatic preaccelerator, accelerating beam up to 60–100 keV.

ISSN:0094-243X    

DOI:10.1063/1.44823

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Characteristics and performance of the recently developed volume H−ion source and the helical electro‐static quadrupole (HESQ) at KEK are described. Observation of the H−beam intensity enhancement by introducing a small amount of cesium vapor is shown. The extracted H−beam current of 20 mA was obtained in the cesium‐mode operation. The measured 90% normalized beam emittance was about 1 &pgr;mm.mrad for 12 mA beam. We found that the workfunction of the plasma electrode surface which was decreased by cesium coverage had an important role to enhance the H−beam intensity. A helical electro‐static quadrupole (HESQ) for focusing low energy and high current negative ion beams has been developed at KEK. Various negative ions such as Cu−and Au−ion beams of more than several mA have been transported and focused with the HESQ. Comparison of the focused beam emittance between measurements and calculations are presented.

ISSN:0094-243X    

DOI:10.1063/1.44824

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Employing the crossed‐beams technique, we have investigated electron‐detachment processes from H−in collisions with multiply‐charged noble gas ions. Absolute cross sections for single‐ and double‐electron removal have been measured at center‐of‐mass energies from 50 keV to 200 keV and ion charge states up to 8. The data is discussed with respect to conversion efficiencies of H−to neutral H0in plasma neutralizers proposed for efficient neutral beam heating of future fusion devices.

ISSN:0094-243X    

DOI:10.1063/1.44825

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The neutral, positive, and negative beam components have been measured at the exit of the gas neutralizer of a powerful D−/H−neutral beam injector. Their relative fractions have been studied as a function of the neutralizer gas target thickness. These experiments used a diagnostic consisting of a large electrostatic deflector and three calorimetric targets, one for each beam component. These measurements have been performed for the first time with high power D−and H−beams (up to 200 kW, multisecond pulses). The negative ion beam energy was varied from 25 to 100 keV/nucleon. The results are in agreement with the theoretical predictions derived from the cross‐sections data. They confirmed in particular, that negative ion neutralization efficiencies of about 60% can be obtained at 100 keV/nucleon.

ISSN:0094-243X    

DOI:10.1063/1.44826

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Analytical and experimental results of studying photoneutralization of the H−ion beams with energy of 20–200 keV by the polarized laser radiation are presented. Polarized‐angular anisotropy effect of distribution along the leaking‐out angles of formed hydrogen atoms has been observed in the case when electric vector of laser radiation was orthogonal to vector of ion beam speed. Anisotropy was characterized by appearing of a dip in the center of hydrogen atoms angular distribution. The contour width of hydrogen atoms beam divergence in the case when polarization vector was collinear to vector of beam speed is decreasing with the growth of beam energy as 1/E1/2. It has been suggested that anisotropy of the H0atoms angular distribution profile is connected with the deformation of the photoelectrons angular distribution profile depending on the polarization vector of radiation.

ISSN:0094-243X    

DOI:10.1063/1.44827

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Results are presented of density and temperature measurements made within a large volume magnetically confined plasma which could be applicable to a plasma neutralizer. rf power at a few megahertz is inductively coupled into an argon plasma by means of a multi‐turn insulated antenna within the plasma chamber. This large volume, dense plasma offers potential advantages over an equivalent plasma created by dc ion source technology, since as no filaments are required for normal operation, possible contamination from filament material is not a problem and more importantly the device requires virtually no maintenance as the need to replace filaments is eliminated.

ISSN:0094-243X    

DOI:10.1063/1.44828

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The work in the field of negative ions at Cadarache aims at a coherent D−beam development in view of the needs of future magnetic fusion experiments. An overview of recent activities is first given: (i) during the recent collaboration with JAERI, 2.2 A, 100 keV, D−long pulse beams have been produced and extensively studied at Cadarache; (ii) the production of negative ions from the Pagoda source is now under study; (iii) two important ITER NB related studies have been conducted, the conceptual study of a 1 MV, 15 A power supply and the design of a 1 MV, 4 A D−beamline and test bed. The future experimental studies, which constitute the main elements of the European strategy in neutral beam development for magnetic fusion applications are the following: (i) the application for financial support in EC has been made for a 1 MeV 0.1 A D−beam acceleration experiment, which is projected to be carried out in 1994; (ii) a new test bed MANTIS for multi‐ampere D−source development will also be established, constituted mainly from equipments previously used on the former DRAGON experiment at Culham Laboratory. This source test bed will operate independently of the present test bed, which is to be upgraded for high‐voltage operation.

ISSN:0094-243X    

DOI:10.1063/1.44829

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A 500 keV, 10 MW neutral beam injector is to be constructed in JT‐60 Upgrade for the experiments of current drive and heating of heat density core plasmas. This is the first neutral beam injector in the world using negative ions as the primary ions. In the design, D−ion beams of 44 A, 500 keV are produced by two ion sources (22 A/each ion source) and neutralized in a long gas neutralizer. The total system efficiency is about 40%. The ion source is a cesium‐seeded multicusp volume source having a three stage electrostatic accelerator. To reduce the stripping loss of D−ions in the accelerator, the ion source should be operated at a low pressure of 0.3 Pa with a current density of 13 mA/cm2. The first test of the full‐size negative ion source is scheduled from middle of 1993.

ISSN:0094-243X    

DOI:10.1063/1.44830

出版商:AIP    

年代:1992

数据来源: AIP