摘要:

The results of experiments on moderate energy (4–25 keV) metal ion beam focusing by a high current plasma lens (PL) are presented. The ion beam was produced by a two-chamber vacuum–arc metal vapor vacuum arc (MEVVA)-type ion source. Characteristics of the beam passing through the lens have been measured and the PL focusing properties determined for a wide range of ion beam energy and current. Distributions have been determined of the external potential along the lens electrodes that provide maximum increase of the beam current density on axis. Certain features of metal ion beam focusing by the PL are discussed. Some of these characteristics depend on the method of application of the external electric potential to the lens electrodes. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148647

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A new ion extraction system has been developed for use with the light ion source apparatus (LIISA) of the Accelerator Laboratory. The aim of the new extraction system is to have a more intense and better quality beam. For simulation of the beam behavior at the extraction region a computer codeIGUNehas been used. The simulation shows that a simple triode extraction would be efficient enough to extract total beam intensities of around 5 mA at an extraction voltage of 10–15 kV. At the same time, with the carefully designed plasma electrode, the emittance could be decreased significantly from the original design. The new extraction was installed in May 1997 and the results have been encouraging. The transport efficiency of the extracted beam to the first Faraday cup (at a distance of 1.2 m) was 100&percent; and the maximum proton current obtained was 2.0 mA. The maximum proton current in the cyclotron inflector is 1.0 mA, which is eight times larger than the previous record. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148648

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Numerical codes based on the model of ion confinement and losses in the electron cyclotron resonance (ECR) source have been applied to the mathematical simulation of krypton and xenon ion production in the 18 GHz ECR ion source at RIKEN. An equation of complete plasma energy is introduced to estimate the rf power of the ECR plasma heating. The final result of fitting is in reasonable agreement with the real experimental data for the Kr and Xe ion production in the source and used to estimate the main plasma parameters. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148649

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

In negative-ion-based neutral beam injection (NBI) systems for the large helical device (LHD), beams must be transported over 13 m from theH−ion source to the injection port. In order to clarify beam deflection by the electron deflection magnets set in a beam extraction grid (EG) and to control beam transport direction, we analyzed beam trajectories. The physics of the beam deflection was studied with theoretical calculations and the deflection angle was estimated by 3D beam trajectory simulation. The evaluated deflection angle was 10 mrad in the opposite direction of the electron deflection when the maximum magnetic field on the beam axis was 480 G and the beam energy was 83.2 keV. The electrostatic lens effect on the beam deflection at the EG exit was estimated to be larger than the magnetic field effect. This deflection was reduced to 2 mrad by a 1.3 mm displacement of the grounded grid (GG) aperture, a result in agreement with experimental results of a1/3-scale model for the LHD ion source. The maximum GG aperture displacement of the LHD ion source was designed as 3.4 mm to reduce the deflection and to focus multibeamlets using the simulation. We have developed the ion source with this design. The targeted performance is a production ofH−beams of 40 A(40 mA/cm2),180 keV. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148651

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Our approach to ion beam modeling breaks down the complex interplay of competing elementary processes into a series of independent consecutive steps. Thus, both in methodological development and computational modeling, the main effort can be directed towards the processes which are of greatest relevance in the context given. Moreover, employment of the special software available allows for comprehensive and efficient optimization of multigrid ion sources for low ion beam divergence and long lifetime, even in a personal computer environment. Here, for our Kaufman-type two-grid ion source RR-ISQ 76 some ion beam characteristics in their dependence on geometrical two-grid configuration are calculated and discussed, first of all in terms of shape and area of the plasma sheath. These dependencies are used to optimize this particular ion source for a low beam divergence. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148652

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A brief review of investigations carried out in the Institute of Physics is presented along with an analysis of processes determining production of ions as well as formation and transport of intense ion beams in plasma-optical systems. All these systems have a common mechanism of space charge equipotentialization. When a noncompensated beam’s self-potential exceeds significantly an external potential, a charge compensation is mainly provided by secondary electron emission. Two systems are considered, a magnetically isolated diode gap (MDG) operating in the plasma-optical regime, and a high-current electrostatic plasma lens. It is demonstrated that a MDG can be used for production of hydrogen ions with unique parameters (current 6 A, density of current6 A/cm2,energy up to 20 keV, pulse duration up to 100 &mgr;s). An effective method of intense ion beam low pressure transport is proposed. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148653

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

It is well known that there exist two distinct types of ion beam neutralization, viz., charge and current neutralization. We have designed and studied a versatile and compact microwave plasma (MP) cathode electron gun dedicated to charge as well as current neutralization. Unlike the conventional hot cathode neutralizer, this MP cathode allows operation of the electron gun in a reactive gaseous environment when it is eventually associated with an electron cyclotron resonance (ECR) ion gun. Charge neutralization can be easily carried out by extracting from the MP cathode through a 1 mm diameter hole, a 35 mA electron beam under a 20 V voltage; the MP cathode being fed with a 75 W microwave power at 2.45 GHz. Higher beam intensities could be obtained using a multiaperture thin plate. Electron beam intensities as high as 300 mA and energies of 2 keV needed for current neutralization, e.g., when an ion beam impinges onto a thick dielectric surface, are obtained via a two-stage arrangement including an anodic chamber associated with a set of three monoaperture plates for the electron beam extraction. Transport of 200–2000 eV electron beams is ensured using focusing optics composed of three aligned tubes 6 cm in diameter and unsymmetrically polarized. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148654

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The article describes a laser ion source torch designed on the basis of aCO2laser at Efremov Institute of Electrophysical Apparatus in collaboration with the Institute for Nuclear Research of the Ukrainian Academy of Science, Kiev. The ion extraction from the laser plasma is done by means of spherical grid electrodes. This permits to improve the efficiency several hundred times compared to the existing ion sources and to increase the ion beam correspondingly, including highly charged ions. The charge composition of the beam, the pulse frequency, and the extracted beam are determined by the operational mode of the laser. ©1998 American Institute of Physics. 

ISSN:0034-6748    

DOI:10.1063/1.1148655

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The spallation neutron source requires an ion source producing anH−beam with a peak current of 35 mA at a 6.2&percent; duty factor. For the design of this ion source, extracted electrons must be transported and dumped without adversely affecting theH−beam optics. Two issues are considered: (1) electron containment transport and controlled removal; and (2) first-orderH−beam steering. For electron containment, various magnetic, geometric, and electrode biasing configurations are analyzed. A kinetic description for the negative ions and electrons is employed with self-consistent fields obtained from a steady-state solution to Poisson’s equation. Guiding center electron trajectories are used when the gyroradius is sufficiently small. The magnetic fields used to control the transport of the electrons and the asymmetric sheath produced by the gyrating electrons steer the ion beam. Scenarios for correcting this steering by split acceleration and focusing electrodes will be considered in some detail. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148716

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

General characteristics of distributed control system software tools are examined from the perspective of ion source control system requirements. Emphasis is placed on strategies for building extensible, distributed systems in which the ion source element is one component of a larger system. Vsystem, a commercial software tool kit from Vista Control Systems was utilized extensively in the control system upgrade of the Holifield Radioactive Ion Beam Facility. Part of the control system is described and the characteristics of Vsystem are examined and compared with those of the Experimental Physics and Industrial Control System (EPICS). ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148717

出版商:AIP    

年代:1998

数据来源: AIP