The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
M Bacal - One of the best experts on this subject based on the ideXlab platform.
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physics aspects of negative Ion Sources
Nuclear Fusion, 2006Co-Authors: M BacalAbstract:The physical phenomena important in volume and surface productIon negative hydrogen Ion Sources are reviewed. The phenomenon, designated volume productIon, was attributed to dissociative electron attachment of low energy electrons to rovibratIonally excited molecules. The experimental verificatIon in 2005 of the reality of this mechanism is reported. Recent results obtained by measuring the negative Ion temperature in a filament discharge Ion source indicate that two negative Ion populatIons are present. Understanding the physics of volume negative Ion Sources operating in accelerators with H− Ion density in the 100 mA cm−2 range opens the prospect of creating volume caesium-free Sources for fusIon. The evolutIon of physics of surface productIon is also described.A measurement effected near the plasma electrode (PE) using two-laser beam photodetachment showed the presence of a directed negative Ion flow. The ratio of the negative Ion and electron currents extracted through the transverse magnetic filter field near the PE can be predicted from a collisIonal flow model. A specific for two negative species plasmas transport mechanism in the weak transverse magnetic filter field is described.
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volume productIon negative hydrogen Ion Sources
IEEE Transactions on Plasma Science, 2005Co-Authors: M Bacal, Akiyoshi Hatayama, J PetersAbstract:We review the evolutIon of volume productIon negative hydrogen Ion Sources since the discovery in 1977 of the new phenomenon, designated as volume productIon and attributed to dissociative electron attachment of low energy electrons to rovibratIonally excited molecules. The experimental verificatIon in 2005 of the reality of this mechanism is reported. The magnetically filtered tandem Sources, using hot filaments or inductively coupled radio frequency discharges, proposed in order to make use of the volume productIon mechanism, are used as continuous wave Sources for cyclotrons and short pulse Sources for synchrotrons. The extractIon physics, required to correlate the negative Ion and electron densities near the extractIon opening with the extracted currents, is discussed taking into account the recently measured H/sup -//D/sup -/ Ion temperatures. It is also shown that the extracted negative Ion current can be predicted from the directed flow velocity (measured by two laser photodetachment) and the negative Ion density measured in the extractIon regIon plasma. Progress in modeling the volume productIon negative hydrogen Ion Sources is briefly summarized. Main attentIon has been paid to some recent topics, such as negative Ion temperature and specific for two negative species plasmas transport in a weak transverse magnetic field. A new view on the potential of volume productIon making use of the vibratIonally excited molecules produced on surfaces (plasma electrode, walls) by recombinative desorptIon is presented.
Ian G. Brown - One of the best experts on this subject based on the ideXlab platform.
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vacuum arc Ion Sources
arXiv: Accelerator Physics, 2014Co-Authors: Ian G. BrownAbstract:The vacuum arc Ion source has evolved into a more or less standard laboratory tool for the productIon of high-current beams of metal Ions, and is now used in a number of different embodiments at many laboratories around the world. ApplicatIons include primarily Ion implantatIon for material surface modificatIon research, and good performance has been obtained for the injectIon of high-current beams of heavy-metal Ions, in particular uranium, into particle accelerators. As the use of the source has grown, so also have the operatIonal characteristics been improved in a variety of different ways. Here we review the principles, design, and performance of vacuum arc Ion Sources.
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Vacuum arc Ion Sources: A review
2012 25th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV), 2012Co-Authors: Ian G. BrownAbstract:The vacuum arc Ion source is unique among the arsenal of Ion Sources available to the experimenter in its capabilities for producing high current beams of metal Ions, thereby providing a tool valuable especially for Ion implantatIon and for accelerator injectIon applicatIons. The source also provides a convenient approach to the investigatIon of fundamental vacuum arc phenomena via analysis of the Ions formed within the metal plasma. First introduced several decades ago, this kind of Ion beam generator is by now a relatively mature and widely used technology. Here we review the basic approach to vacuum arc Ion source design, source embodiments that have been made and used around the world, their applicatIons in several fields, and the vacuum arc plasma physics that has been explored using this kind of device as a diagnostic tool.
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vacuum arc Ion Sources
Review of Scientific Instruments, 1994Co-Authors: Ian G. BrownAbstract:The vacuum arc is a rich source of highly Ionized metal plasma that can be used to make a high current metal Ion source. Vacuum arc Ion Sources have been developed for a range of applicatIons including Ion implantatIon for materials surface modificatIon, particle accelerator injectIon for fundamental nuclear physics research, and other fundamental and applied purposes. The beam parameters can be attractive, and the source has provided a valuable additIon to the spectrum of Ion Sources available to the experimenter. Beams have been produced from over 50 of the solid metals of the periodic table, with mean Ion energy up to several hundred keV and with beam current up to several amperes. Typically the source is repetitively pulsed with pulse length of order a millisecond and duty cycle of order 1%, and operatIon of a dc embodiment has been demonstrated. Here the source fundamentals and operatIon are reviewed, the source and beam characteristics summarized, and some applicatIons examined.
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The Physics and Technology of Ion Sources, Second EditIon - Vacuum Arc Ion Sources
Review of Scientific Instruments, 1994Co-Authors: Ian G. BrownAbstract:The vacuum arc is a rich source of highly Ionized metal plasma that can be used to make a high current metal Ion source. Vacuum arc Ion Sources have been developed for a range of applicatIons including Ion implantatIon for materials surface modificatIon, particle accelerator injectIon for fundamental nuclear physics research, and other fundamental and applied purposes. The beam parameters can be attractive, and the source has provided a valuable additIon to the spectrum of Ion Sources available to the experimenter. Beams have been produced from over 50 of the solid metals of the periodic table, with mean Ion energy up to several hundred keV and with beam current up to several amperes. Typically the source is repetitively pulsed with pulse length of order a millisecond and duty cycle of order 1%, and operatIon of a dc embodiment has been demonstrated. Here the source fundamentals and operatIon are reviewed, the source and beam characteristics summarized, and some applicatIons examined.
Beidou Dong - One of the best experts on this subject based on the ideXlab platform.
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The thermophysical characteristics of the Ionizer in cesium sputter‐type negative Ion Sources
Review of Scientific Instruments, 1992Co-Authors: Boling Xi, Houpeng Chen, Beidou DongAbstract:The thermophysical characteristics of the Ionizer in cesium sputter‐type negative Ion Sources is studied by means of the heat transfer theory in this paper. A heat transfer model is given and theoretical calculatIons are performed. The theoretical calculatIons are in good agreement with experimental results. Based on the theoretical analysis the configuratIon of the source is improved and the calorific efficiency is increased, so that the temperature of the Ionizer can reach up to 1300 K and the lifetime of the heater core of the Ionizer is prolonged. The theoretical model can serve as the basis for the Ionizer design of the cesium sputter‐type negative Ion Sources. In additIon, the study is also helpful for the design of the heater in the similar Ion Sources.
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Study on the mechanism of negative Ion formatIon in cesium sputter‐type negative Ion Sources
Review of Scientific Instruments, 1992Co-Authors: Houpeng Chen, Boling Xi, Beidou DongAbstract:The mechanism of forming negative Ions in cesium sputter negative Ion Sources is studied by means of a modified dipole layer model and quantum theory. Formulas of the change of work functIon on the metal surface adsorbing cesium layer and the electron transfer probability are given. The formatIon probabilities of the negative Ions are derived using a quantum tunneling model. The negative Ion yield is also calculated. The calculated results are in essential agreement with the experimental data. The philosophy described in this paper may offer a useful theoretical model for the mechanism study of cesium sputter negative Ion Sources.
Junzo Ishikawa - One of the best experts on this subject based on the ideXlab platform.
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ApplicatIons of heavy-negative-Ion Sources for materials science (invited)
Review of Scientific Instruments, 2000Co-Authors: Junzo IshikawaAbstract:ApplicatIons of heavy negative Ions produced by sputter-type negative-Ion Sources for materials science are reviewed. Submilliampere and milliampere heavy-negative-Ion beams can be produced by a neutral- and Ionized-alkaline–metal-bombardment-type heavy-negative-Ion source and rf plasma sputter-type negative-Ion Sources, respectively. These negative-Ion beams can be applied for materials processing such as Ion implantatIon, Ion beam etching, and Ion beam depositIon. In negative-Ion implantatIon the charge-up of implanted material surfaces is greatly reduced, and thus Ion implantatIon without target charging is possible. The etching rate due to fluorine-negative Ion is mainly determined by its kinetic energy. Pure diamondlike carbon films with high sp3 structure have been prepared by C− and C2− Ion beam depositIon, and CN films by CN− Ion beam depositIon. Negative Ions provide an excellent tool for materials processing applicatIons.
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Negative‐Ion Sources for modificatIon of materials (invited)
Review of Scientific Instruments, 1996Co-Authors: Junzo IshikawaAbstract: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.
Roderich Keller - One of the best experts on this subject based on the ideXlab platform.
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Primary Ion Sources for EBIS devices
AIP Conference Proceedings, 2008Co-Authors: Roderich KellerAbstract:The Ion‐optical conditIons for primary Ion Sources that could be installed in an EBIS injector are derived, assuming a realistic set of fixed parameters to be imposed by the EBIS. It is shown how these requirements may be met, and that beam currents of up to 2 mA can be generated with the postulated emittance. This derivatIon, even though carried out for one specific case, gives general guide lines how to proceede for other conditIons as well. In the second part, different types of Ion Sources are presented that are likely candidates for EBIS injector Sources. Beam current examples are given and the basic features of the Sources discussed. The emphasis of this paper is put on the reliable productIon of Ion beams, rather than attempting to furnish a representative cross sectIon of the existing Ion source varieties.
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Primary Ion Sources for EBIS devices
AIP Conference Proceedings, 2008Co-Authors: Roderich KellerAbstract:The Ion‐optical conditIons for primary Ion Sources that could be installed in an EBIS injector are derived, assuming a realistic set of fixed parameters to be imposed by the EBIS. It is shown how these requirements may be met, and that beam currents of up to 2 mA can be generated with the postulated emittance. This derivatIon, even though carried out for one specific case, gives general guide lines how to proceede for other conditIons as well. In the second part, different types of Ion Sources are presented that are likely candidates for EBIS injector Sources. Beam current examples are given and the basic features of the Sources discussed. The emphasis of this paper is put on the reliable productIon of Ion beams, rather than attempting to furnish a representative cross sectIon of the existing Ion source varieties.
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Primary Ion Sources for EBIS
Lawrence Berkeley National Laboratory, 2001Co-Authors: Roderich KellerAbstract:This paper gives an introductIon into the topic of primary Ion Sources that can be used to feed Ions of normally solid elements into EBIS devices. Starting with a set of typical requirements for primary Ion Sources, some major types of Ion generators are discussed first, with emphasis on their working principles rather than trying to give a fully representative listing of used and proposed generators. Beam-transport issues between primary Ion source and EBIS are then examined, and generic characteristics of suitable beam-formatIon and transport systems are explained.
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Primary Ion Sources for EBIS - eScholarship
2001Co-Authors: Roderich KellerAbstract:Primary Ion Sources for EBIS* Roderich Keller Ernest Orlando Lawrence Berkeley NatIonal Laboratory Berkeley, CA 94720, USA Abstract. This paper gives an introductIon into the topic of primary Ion Sources that can be used to feed Ions of normally solid elements into EBIS devices. Starting with a set of typical requirements for primary Ion Sources, some major types of Ion generators are discussed first, with emphasis on their working principles rather than trying to give a fully representative listing of used and proposed generators. Beam-transport issues between primary Ion source and EBIS are then examined, and generic characteristics of suitable beam-formatIon and transport systems are explained. INTRODUCTIon While feeding of gaseous substances into EBIS devices is straightforward, the use of elements with low vapor pressure under normal conditIons presents its challenges, due to the unique set of functIonal requirements for a typical EBIS discharge chamber, with coexisting conditIons of ultra-high vacuum, high voltage, high magnetic field, and sharp mechanical alignment tolerances. Use of an external injector–or primary–Ion source then becomes a viable and even preferred mode of operatIon, as opposed to generating the desired free particles inside the EBIS. In combinatIon with a mass sep- arator, the primary Ion source can also provide feeds of a single element in a single charge state, drastically reducing the loss of main-beam current in the form of un- wanted species. It might further be beneficial for the final product to start the Ion- izatIon process within the EBIS with already Ionized particles for example, to keep the background gas pressure as low as possible, thereby reducing recombinatIon losses. On the other hand, one should not underestimate the effort needed to efficiently utilize a primary Ion source; both the particle generatIon as well as the primary beam transport issues need to be taken care of when high performance levels are aimed at. These two subjects are discussed in the main part of this paper, after outlining typical conditIons towards which they are geared. *Work supported by the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under Contr. No. DE-AC03-76SF00098
