摘要:

Tandem‐accelerator operation requires a source of negative ions. The earliest negative‐ion sources were based on charge exchange of positive ions from a rf or duoplasmatron source. The development of the sputter‐ion source in the 1970’s produced a revolutionary change in the number of negative‐ion beams for Tandem operation. This article will review operational characteristics of sputter‐ion sources coupled to large Tandem accelerators. These characteristics and matching of the ion source to the accelerator are determining factors for the production of useful beam intensities for physics experiments. A new approach using a 2.45 GHz microwave ion source to produce a high‐quality, positive‐ion beam coupled to a charge‐exchange canal is being developed at Chalk River Laboratories, and some results of this development program will be presented. Plans for future development include the investigation of direct extraction of negative ions from a microwave‐driven plasma. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146648

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The properties of negative ions, such as charging–free ion implantation and new materials syntheses by pure kinetic bonding reaction, have been shown to be promising in terms of their interaction with material surfaces. However, high‐current or high‐brightness negative‐ion sources are required for these purposes. Several kinds of sputter‐type negative‐ion sources have been developed for negative‐ion implantation and deposition in order to obtain high‐current heavy negative ions. Recently, a microwave discharge oxygen negative‐ion source for negative‐ion beam deposition and a surface plasma type hydrogen negative‐ion source for projection ion‐beam lithography have been investigated. In this article, these negative‐ion sources for modification of materials are reviewed. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146682

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The origin of memory effects in the Chalk River accelerator mass spectrometry sputter ion source has been studied by tracer and elastic‐recoil‐detection surface analysis techniques. For36Cl measurements, the results indicate that the memory arises from contamination of the region immediately surrounding the sample and that it can be mitigated by operating this portion of the ion source above 350 °C. This has reduced memory effects by a factor of 10 or more and has resulted in a similar improvement in background. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146683

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

An atomic beam polarized ion source, used heavily since 1989 for producing polarized H±and D±beams for experiments between 25 keV and 20 MeV, have been modified to accept a Lamb–shift, spin–filter polarimeter. In this source, polarized ground‐state H or D atoms enter an electron cyclotron resonance ionizer where they are stripped to produce an outgoing positive polarized ion beam. When negative ions are desired, cesium vapor is introduced into a downstream charge‐exchange canal. The polarimeter, based on an atomic physics concept first developed to produce nuclear–spin‐polarized beams at Los Alamos, is designed to monitor the polarization of2S1/2metastable H or D atoms emerging from this cesium canal. Metastable2S1/2atoms created by electron pickup in a collision with cesium are ‘‘filtered’’ by the polarimeter according to a magnetic substate, as the magnetic field imposed on the polarimeter cavity is tuned between 53 and 61 mT. Photons produced by subsequent quenching of these filtered atoms to their ground state are monitored downstream by a phototube to reveal the magnetic substate population of the incident positive beam. To install the polarimeter cavity and phototube assembly, the existing polarized ion source was lengthened by 30 cm. Installation is complete, its calibration has been checked, and initial impressions gained from its use are presented. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1146684

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Collisions of slow multicharged and highly charged ions, i.e., ions with kinetic energies up to some 10 keV, with atoms in the gas phase and with solids have been studied in detail over the last few years. A brief review is presented on some typical experiments and their results which make use of the specific features of highly charged ions in the fields of atomic spectroscopy, ion–atom collisions, and ion–solid interactions. In particular recent progress in the understanding of the interaction mechanisms of highly charged ions with solid surfaces will be discussed. ©1996 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1147248

出版商:AIP    

年代:1996

数据来源: AIP