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Cyclotron Resonance Heating of a Deuterium Plasma

Description: Abstract: "The energy gained by a deuterium plasma, from a three megacycle per second radiofrequency field, was studied experimentally. A static magnetic field, in the form of a "mirror", was used. The coil of an rf resonant circuit, placed at the center of the machine produced a time-varying magnetic field parallel to the static field. This, in turn, induced an electrical field, in an azmuthal direction, which acted on the ions. When this was in synchronism with the cyclotron frequency, the ions could pick up energy. At this resonance the light intensity from the plasma increased markedly. This effect was used as evidence for the transfer of energy to the ions."
Date: October 28, 1957
Creator: Chambers, Edmund S.; Lamb, William A. S. & Kippenhan, Dean O.
Partner: UNT Libraries Government Documents Department

Cyclotron resonance absorption by a hydrogen plasma

Description: From introduction: "The work described in this report was undertaken as part of an experimental study to determine the effectiveness of radiofrequency field in heating the ions of a hydrogen or deuterium plasma. The ultimate aim is to find a method of heating a deuterium plasma until an appreciable rate of nuclear reaction takes place."
Date: August 30, 1957
Creator: Chambers, Edmund S.
Partner: UNT Libraries Government Documents Department

Strong Resonant Intersubband Magnetopolaron Effect in Heavily Modulation-Doped GaAs/AlGaAs Single Quantum Wells at High Magnetic Fields

Description: Electron cyclotron resonance (CR) has been studied in magnetic fields up to 32 T in two heavily modulation -d-doped GaAs/Al{sub 0.3}Ga{sub 0.7}As single-quantum-well. Little effect on electron CR is observed in either sample in the region of resonance with the GaAs LO phonons. However, above w{sub LO} at B > 27 T, electron CR exhibits a strong avoided-level-crossing splitting for both samples at energies close to E{sub LO} + (E{sub 2}-E{sub 1}), where E{sub 2}, and E{sub 1} are the energies of the bottoms of the second and the first subbands, respectively. The energy separation between the two branches is large, reaching a minimum of about 40 cm{sup {minus}1} around 30.5 T for both samples. This splitting is due to a three-level resonance between the second LL of the first electron subband and the lowest LL of the second subband plus a LO phonon. The large splitting in the presence of high electron densities is due to the absence of occupation (Pauli-principle) effects in the final states and weak screening for this three level process.
Date: July 20, 1999
Creator: Jiang, H.W.; Jones, E.; Lee, X.Y.; Leem, Y.A.; McCombe, B.D.; Peeters, F.M. et al.
Partner: UNT Libraries Government Documents Department

Current Drive in a Ponderomotive Potential with Sign Reversal

Description: Noninductive current drive can be accomplished through ponderomotive forces with high efficiency when the potential changes sign over the interaction region. The effect can practiced upon both ions and electrons. The current drive efficiencies, in principle, might be higher than those possible with conventional radio-frequency current-drive techniques, since different considerations come into play.
Date: July 30, 2003
Creator: Fisch, N.J.; Rax, J.M. & Dodin, I.Y.
Partner: UNT Libraries Government Documents Department

High performance single stage operation of the LBL ECR and the design of an advanced ECR ion source

Description: A new mode of operation using only the second stage of the LBL ECR has been developed. This single stage mode produces charge states and currents equal to or better than the traditional two stage operation of the LBL ECR for a variety of gases such as nitrogen, oxygen, and argon. The critical parameter for this mode appears to be conditioning the plasma chamber walls with a coating of SiO/sub 2/. Various models to explain this effect will be discussed along with implications for ECR ion source design. A new Advanced ECR ion source which will operate at 14 GHz is being designed for the 88-Inch Cyclotron. Construction is scheduled to begin in the fall of 1988 and test operation should begin in the fall of 1989. The design includes hollow core copper wire solenoids, iron yoke, a Nd-Fe-B sextupole, radial pumping, and access to the plasma chamber. 8 refs., 4 figs., 1 tab.
Date: September 1, 1988
Creator: Lyneis, C.M.
Partner: UNT Libraries Government Documents Department

Electron Bernstein Wave Research on NSTX and CDX-U

Description: Studies of thermally emitted electron Bernstein waves (EBWs) on CDX-U and NSTX, via mode conversion (MC) to electromagnetic radiation, support the use of EBWs to measure the Te profile and provide local electron heating and current drive (CD) in overdense spherical torus plasmas. An X-mode antenna with radially adjustable limiters successfully controlled EBW MC on CDX-U and enhanced MC efficiency to {approx} 100%. So far the X-mode MC efficiency on NSTX has been increased by a similar technique to 40-50% and future experiments are focused on achieving * 80% MC. MC efficiencies on both machines agree well with theoretical predictions. Ray tracing and Fokker-Planck modeling for NSTX equilibria are being conducted to support the design of a 3 MW, 15 GHz EBW heating and CD system for NSTX to assist non-inductive plasma startup, current ramp up, and to provide local electron heating and CD in high beta NSTX plasmas.
Date: June 10, 2003
Creator: Taylor, G.; Efthimion, P.C.; Jones, B.; Bell, G.L.; Bers, A.; Bigelow, T.S. et al.
Partner: UNT Libraries Government Documents Department

ECR sources for the production of highly charged ions

Description: Electron Cyclotron Resonance Ion Sources (ECRIS) using RF between 5 and 16 GHz have been developed into stable, reliable sources of highly charged ions produced from a wide range of elements. These devices are currently used as ion sources for cyclotrons, synchrotrons, and heavy-ion linacs for nuclear and relativistic heavy-ion physics. They also serve the atomic physics community as a source of low energy multiply-charged ions. In order to improve their performance both with respect to maximum charge state and beam intensity, ECRIS builders are now designing and constructing sources which will operate at frequencies up to 30 GHz. In this paper we review the present status of operating ECRIS, review recent experimental measurements on plasma parameters, and look at the technology and potential of sources operating at frequencies up to 30 GHz. 14 refs., 4 figs., 1 tab.
Date: September 1, 1989
Creator: Lyneis, C.M.; Antaya, T.A (Lawrence Berkeley Lab., CA (USA) & Michigan State Univ., East Lansing, MI (USA))
Partner: UNT Libraries Government Documents Department

ECR (Electron Cyclotron Resonance) ion sources for cyclotrons

Description: In the last decade ECR (Electron Cyclotron Resonance) ion sources have evolved from a single large, power consuming, complex prototype into a variety of compact, simple, reliable, efficient, high performance sources of high charge state ions for accelerators and atomic physics. The coupling of ECR sources to cyclotrons has resulted in significant performance gains in energy, intensity, reliability, and variety of ion species. Seven ECR sources are in regular operation with cyclotrons and numerous other projects are under development or in the planning stag. At least four laboratories have ECR sources dedicated for atomic physics research and other atomic physics programs share ECR sources with cyclotrons. An ECR source is now installed on the injector for the CERN SPS synchrotron to accelerate O/sup 8 +/ to relativistic energies. A project is underway at Argonne to couple an ECR source to a superconducting heavy-ion linac. Although tremendous progress has been made, the field of ECR sources is still a relatively young technology and there is still the potential for further advances both in source development and understanding of the plasma physics. The development of ECR sources is reviewed. The important physics mechanisms which come into play in the operation of ECR Sources are discussed, along with various models for charge state distributions (CSD). The design and performance of several ECR sources are compared. The 88-Inch Cyclotron and the LBL ECR is used as an example of cyclotron+ECR operation. The future of ECR sources is considered.
Date: October 1, 1986
Creator: Lyneis, C.M.
Partner: UNT Libraries Government Documents Department

Progress on the LBL ECR heavy ion source

Description: The LBL ECR ion source, which began test operation in January 1984, has already produced a variety of high charge state heavy ion beams of sufficient intensity for cyclotron operation, although actual use must wait for completion of the beam transport system. The source has produced 40 ..mu..A of O/sup 6 +/, 2 ..mu..A of O/sup 7 +/, 40 ..mu..A of Ar/sup 8 +/, and 0.20 ..mu..A of Ar/sup 12 +/. The source development has centered on optimizing source performance with modifications and parameter tuning. Future plans include construction of an SmCo/sub 5/ octupole structure, and testing of solid feed techniques. The construction of the beam transport line and calculations on center region geometry for heavy ion axial injection into the 88-Inch Cyclotron are also underway.
Date: April 1, 1984
Creator: Clark, D. J.; Jongen, Y. & Lyneis, C. M.
Partner: UNT Libraries Government Documents Department

Performance of the LBL AECR source at various frequencies

Description: To study the effects of frequency on an electron cyclotron resonance (ECR) ion source, the LBL Advanced ECR ion source (designed to operate at 14 GHz) has been tested at 6.4, 10, and 14 GHz with one plasma chamber (ID = 6.0 cm), a permanent sextuple magnet ( closed sextuple'') with a field strength of 0.84 Tesla at the chamber wall, and no radial vacuum pumping. Pure oxygen was used as the running gas for a fair comparison. The source was tested as a single stage, as well as with cold electron injection using an electron gun in place of a conventional microwave-driven first stage. Higher frequency, with a higher axial magnetic field to ensure a closed ECR zone for electron heating, does give better performance. As demonstrated before, at each frequency electron injection led to about a factor of two increase in the high charge state oxygen beam intensity. The 14 GHz performance of the AECR source with the closed sextuple magnet was compared to the slotted sextuple'' (a plasma chamber with radial pumping slots of 7.0-cm dia and a weaker magnet of 0.64 Tesla at the chamber wall). Results show that a stronger sextuple magnet alone does not automatically improve the source performance.
Date: July 1, 1992
Creator: Xie, Z.Q.; Lyneis, C.M.; Lundgren, S.A. & Collins, D.
Partner: UNT Libraries Government Documents Department

ECR (electron cyclotron resonance) ion sources and applications with heavy-ion linacs

Description: The electron cyclotron resonance (ECR) ion source has been developed in the last few years into a reliable source of high charge-state heavy ions. The availability of heavy ions with relatively large charge-to-mass ratios (0.1--0.5) has made it possible to contemplate essentially new classes of heavy-ion linear accelerators. In this talk, I shall review the state-of-the-art in ECR source performance and describe some of the implications this performance level has for heavy-ion linear accelerator design. The present linear accelerator projects using ECR ion sources will be noted and the performance requirements of the ECR source for these projects will be reviewed. 30 refs., 3 figs.
Date: January 1, 1990
Creator: Pardo, R.C.
Partner: UNT Libraries Government Documents Department

Molecular uranates - laser synthesis of uranium oxide anions in the gas phase

Description: Laser ablation of solid UO{sub 3} or (NH{sub 4}){sub 2}U{sub 2}O{sub 7} yielded in the gas phase molecular uranium oxide anions with compositions ranging from [UO{sub n}]{sup -} (n = 2-4) to [U{sub 14}O{sub n}]{sup -} (n = 32-35), as detected by Fourier transform ion cyclotron resonance mass spectrometry. The cluster series [U{sub x}O{sub 3x}]{sup -} for x {le} 6 and various [U{sub x}O{sub 3x-y}]{sup -}, in which y increased with increasing x, could be identified. A few anions with H atoms were also present, and their abundance increased when hydrated UO{sub 3} was used in place of anhydrous UO{sub 3}. Collision-induced dissociation experiments with some of the lower m/z cluster anions supported extended structures in which neutral UO{sub 3} constitutes the building block. Cationic uranium oxide clusters [U{sub x}O{sub n}]{sup +} (x = 2-9; n = 3-24) could also be produced and are briefly discussed. Common trends in the O/U ratios for both negative and positive clusters could be unveiled.
Date: December 14, 2009
Creator: Marcalo, Joaquim; Santos, Marta; Pires de Matos, Antonio & Gibson, John K
Partner: UNT Libraries Government Documents Department

Plasma and Beam Production Experiments with HYBRIS, aMicrowave-assisted H- Ion

Description: A two-stage ion source concept had been presented a few years ago, consisting of a proven H- ion source and a 2.45-GHz Electron Cyclotron-Resonance (ECR) type ion source, here used as a plasma cathode. This paper describes the experimental development path pursued at Lawrence Berkeley National Laboratory, from the early concept to a working unit that produces plasma in both stages and creates a negative particle beam. Without cesiation applied to the second stage, the H{sup -} fraction of this beam is very low, yielding 75 micro-amperes of extracted ion beam current at best. The apparent limitations of this approach and envisaged improvements are discussed.
Date: September 13, 2006
Creator: Keller, R. AUTHOR-Kwan, S.; Hahto, S.; Regis, M. & Wallig, J.
Partner: UNT Libraries Government Documents Department

Modeling the shell type TeV supernove remnant RX J1713-3946

Description: We simulate the shock waves of shell type supernova remnants with a prototype progenitor of 15 M{sub {circle_dot}} and fit the size and lifetime of SNR RX J1713-3946 with a density of {approx} 1O{sup -26}g cm{sup -3} for the shocked downstream plasma. Such a density is required for efficient stochastic electron acceleration and leads to a thermal X-ray flux more than one order of magnitude lower than the observed featureless X-ray flux. Fast mode waves must be excited to have efficient stochastic electron acceleration. We find that (1) the acceleration efficiency needs to be at least 10 times higher than that through the cyclotron resonances, implying much more efficient acceleration through the transit-time damping process, and (2) the distribution of the accelerated electrons is very sensitive to the ratio of the speed in the downstream to the shock suggesting a dynamo process that can regulate the magnetic field in such a way that the electron distribution doesn't change dramatically throughout the evolution history of the shock waves.
Date: January 1, 2009
Creator: Fryer, Christopher Lee; Fan, Zhonghui & Liu, Siming
Partner: UNT Libraries Government Documents Department

Cyclotron resonance and quasiparticles

Description: This introductory paper contains personal perspectives about the importance of cyclotron resonance in forming our modern view of solids. The papers following this one will discuss the discovery, refinements, and some of the latest developments. Although I will touch on some of these subjects, I leave the details to the other authors and in the main focus on the conceptual impact of the work. I propose that it was experiments based on cyclotron resonance which established the quasiparticle concept.
Date: January 15, 2005
Creator: Cohen, Marvin L.
Partner: UNT Libraries Government Documents Department

Concluding remarks for ECRIS '02

Description: ECRIS'02 was held in Jyvaeskylae Finland at the edge of Lake Jyvaeskylae, which was beautiful location to meet and discuss the state of Electron Cyclotron Resonance ion sources. It was the 15th ECR Ion Source Workshop in a series stretching back to the first workshop held November 6, 1978 in Karlsruhe Germany. Overall, the workshop reports could be characterized as showing solid achievements and steady progress without any spectacular breakthroughs or highly controversial new ideas. In this short report, I will mention some of the highlights and surprises of the workshop that I observed during the meeting and reported on at the close of the meeting. As such, it will be relatively brief and not meant to be all encompassing. A short list of items that made this workshop memorable is given.
Date: September 9, 2002
Creator: Lyneis, Claude
Partner: UNT Libraries Government Documents Department

ECR-based atomic collision physics research at ORNL

Description: After a brief summary of the present capability and configuration of the ORNL Multicharged Ion Research Facility (MIRF), and of upcoming upgrades and expansions, the presently on-line atomic collisions experiments are described. In the process, the utility of intense, cw ion beams extracted from ECR ion sources for low-signal rate experiments is illustrated.
Date: April 1997
Creator: Meyer, F. W.; Bannister, M. E.; Hale, J. W. & Havener, C. C.
Partner: UNT Libraries Government Documents Department

Future prospects for ECR ion sources with improved charge state distributions

Description: Despite the steady advance in the technology of the ECR ion source, present art forms have not yet reached their full potential in terms of charge state and intensity within a particular charge state, in part, because of the narrow band width. single-frequency microwave radiation used to heat the plasma electrons. This article identifies fundamentally important methods which may enhance the performances of ECR ion sources through the use of: (1) a tailored magnetic field configuration (spatial domain) in combination with single-frequency microwave radiation to create a large uniformly distributed ECR ``volume`` or (2) the use of broadband frequency domain techniques (variable-frequency, broad-band frequency, or multiple-discrete-frequency microwave radiation), derived from standard TWT technology, to transform the resonant plasma ``surfaces`` of traditional ECR ion sources into resonant plasma ``volume``. The creation of a large ECR plasma ``volume`` permits coupling of more power into the plasma, resulting in the heating of a much larger electron population to higher energies, thereby producing higher charge state ions and much higher intensities within a particular charge state than possible in present forms of` the source. The ECR ion source concepts described in this article offer exciting opportunities to significantly advance the-state-of-the-art of ECR technology and as a consequence, open new opportunities in fundamental and applied research and for a variety of industrial applications.
Date: December 31, 1995
Creator: Alton, G.D.
Partner: UNT Libraries Government Documents Department

Design of fast tuning elements for the ITER ICH system

Description: The coupling between the ion cyclotron (IC) antenna and the ITER plasma (as expressed by the load resistance the antenna sees) will experience relatively fast variations due to plasma edge profile modifications. If uncompensated, these will cause an increase in the amount of power reflected back to the transmitter and ultimately a decrease in the amount of radio frequency (rf) power to the plasma caused by protective suppression of the amount of rf power generated by the transmitter. The goals of this task were to study several alternate designs for a tuning and matching (T&M) system and to recommend some research and development (R&D) tasks that could be carried out to test some of the most promising concepts. Analyses of five different T&M configurations are presented in this report. They each have different advantages and disadvantages, and the choice among them must be made depending on the requirements for the IC system. Several general conclusions emerge from our study: The use of a hybrid splitter as a passive reflected-power dump [``edge localized mode (ELM)-dump``] appears very promising; this configuration will protect the rf power sources from reflected power during changes in plasma loading due to plasma motion or profile changes (e.g., ELM- induced changes in the plasma scrape-off region) and requires no active control of the rf system. Trade-offs between simplicity of design and capability of the system must be made. Simple system designs with few components near the antenna either have high voltages over considerable distances of transmission lines, or they are not easily tuned to operate at different frequencies. Designs using frequency shifts and/or fast tuning elements can provide fast matching over a wide range of plasma loading; however, the designs studied here require components near the antenna, complicating assembly and maintenance. Capacitor-tuned resonant systems may offer a ...
Date: May 1, 1996
Creator: Swain, D.W. & Goulding, R.H.
Partner: UNT Libraries Government Documents Department

A new 14 GHz electron-cyclotron-resonance ion source (ECRIS) for the heavy ion accelerator facility ATLAS: a status report

Description: A new 14 GHz ECRIS has been designed and built over the last 2 years. The source, a modification of the Berkeley AECR, incorporates the latest results from ECR developments to produce intense beams of highly charged ions, i.e., an improved electron confinement with an axial magnetic mirror ratio of 3.5 and a radial magnetic field inside the plasma chamber of 1.0 T. The aluminium plasma chamber and extraction electrode as well as a biased disk on axis at the microwave injection side donate additional electrons to the plasma, making use of the large secondary electron yield from Al oxide. Slots in the plasma chamber allow for radial pumping which increases the AECR performance. The source will also be capable of additional ECR plasma heating using two frequencies simultaneously to increase the electron energy gain for producing high charge states. To be able to deliver usable intensities of the heaviest ion beams, the design will also allow for axial access for metal evaporation ovens and solid material samples using plasma sputtering. Main design goal is to produce several e{mu}A of U{sup 34+} in order to obtain Coulomb- barrier energies from ATLAS without further stripping.
Date: November 1, 1996
Creator: Schlapp, M.; Vondrasek, R.C.; Szczech, J.; Billquist, P.J.; Pardo, R.C. & Xie, Z.Q.
Partner: UNT Libraries Government Documents Department

A new 14 GHz Electron-Cyclotron-Resonance Ion Source (ECRIS) for the heavy ion accelerator facility ATLAS

Description: A 14 GHz Electron-Cyclotron-Resonance Ion Source (ECRIS) has been designed and built at Argonne National Laboratory. The source is a modification of the AECR at Berkeley and incorporates the latest results from ECR developments to produce intense beams of highly charged ions, including an improved magnetic confinement of the plasma electrons with an axial mirror ratio of 3.5. The aluminum plasma chamber and extraction electrode as well as a biased disk on axis at the microwave injection side donates additional electrons to the plasma, making use of the large secondary electron yield from aluminum oxide. The source is capable of ECR plasma heating using two different frequencies simultaneously to increase the electron energy gain for the production of high charge states. The main design goal is to produce several e{mu}A of at least {sup 238}U{sup 35+} in order to accelerate the beam to coulomb-barrier energies without further stripping. First charge state distributions for gaseous elements have been measured and 210 e{mu}A {sup 16}O{sup 7+} has been achieved. A normalized 90% emittance from 0.1 to 0.2 {pi} mm{sm_bullet}mrad for krypton and oxygen beam has been found.
Date: November 1997
Creator: Schlapp, M.; Pardo, R. C.; Vondrasek, R. C.; Billquist, P. J. & Szczech, J.
Partner: UNT Libraries Government Documents Department