Ion confinement in electron cyclotron resonance ion sources (ECRIS): importance of nonlinear plasma-wave interaction

Ivanov, А.А.; Wiesemann, K.

doi:10.1109/tps.2005.860078

Cited by 32 publications

(17 citation statements)

References 45 publications

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“…the increase of the extracted currents of highly charged ions of a heavier element by mixing lighter gas into the ECR discharge. Since the discovery of the technique, several mechanisms have been proposed to explain the effect [10,11]. In the case of the charge breeder, the most probable cause is ion cooling [12,13] resulting from the mass effect in ion-ion collisions, that makes Na-He collisions more effective than Na-O ones.…”

Section: Charge Breedingmentioning

confidence: 99%

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Diagnostics of a charge breeder electron cyclotron resonance ion source helium plasma with the injection ofNa231+ions

Tarvainen

Koivisto

Galatà

et al. 2016

Phys. Rev. Accel. Beams

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This work describes the utilization of an injected 23 Na 1þ ion beam as a diagnostics of the helium plasma of a charge breeder electron cyclotron resonance ion source. The obtained data allows estimating the upper limit for the ion-ion collision mean-free path of the incident sodium ions, the lower limit of ion-ion collision frequencies for all charge states of the sodium ions and the lower limit of the helium plasma density. The ion-ion collision frequencies of high charge state ions are shown to be at least on the order of 1-10 MHz and the plasma density is estimated to be on the order of 10 11 cm −3 or higher. The experimental results are compared to simulations of the 23 Na 1þ capture into the helium plasma. The results indicate that the lower breeding efficiency of light ions in comparison to heavier elements is probably due to different capture efficiencies in which the in-flight ionization of the incident 1þ ions plays a vital role.

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Section: Charge Breedingmentioning

confidence: 99%

“…Estimated lower limit for the charge breeder helium plasma (electron) density as a function of microwave power.Plasma density [cm −3 ] 1.6×1011 3.1×10 11 4.0×1011 4.4×1011 …”

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confidence: 99%

Diagnostics of a charge breeder electron cyclotron resonance ion source helium plasma with the injection ofNa231+ions

Tarvainen

Koivisto

Galatà

et al. 2016

Phys. Rev. Accel. Beams

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“…Further, the linear Landau damping is exponentially weak at the low velocities of the ion sound wave in the plasma. The observed trends in the intensities of Kr isotopes may be due to the nonlinear effects (induced ion sound wave scattering on ions), which take the smallness of the relative mass difference (ΔA/A) into account to model the heating mechanism of the ions having different charge to mass ratios in two‐component plasmas. The comparison of the present results with previously studied Xe plasma , which showed complete absence of the isotope anomaly, further indicates that the relative mass difference plays some role to yield final ion intensities in the plasma.…”

Section: Resultsmentioning

confidence: 99%

Charge state distribution studies of pure and oxygen mixed krypton ECR plasma – signature of isotope anomaly and gas mixing effect

2016

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We report the charge state distributions of the pure, 25% and 50% oxygen mixed krypton plasma to shed more light on the understanding of the gas mixing and the isotope anomaly [A. G. Drentje, Rev. Sci. Instrum. 63 (1992) 2875 and Y Kawai, D Meyer, A Nadzeyka, U Wolters and K Wiesemann, Plasma Sources Sci. Technol. 10 (2001) 451] in the electron cyclotron resonance (ECR) plasmas. The krypton plasma was produced using a 10 GHz all-permanent-magnet ECR ion source. The intensities of the highly abundant four isotopes, viz. Kr (~11.58%), Kr (~11.49%), Kr (~57%) and Kr (17.3%) up to ~ +14 charge state have been measured by extracting the ions from the plasma and analysing them in the mass and the energy using a large acceptance analyzer-cum-switching dipole magnet. The influence of the oxygen gas mixing on the isotopic krypton ion intensities is clearly evidenced beyond +9 charge state. With and without oxygen mixing, the charge state distribution of the krypton ECR plasma shows the isotope anomaly with unusual trends. The anomaly in the intensities of the isotopes having quite closer natural abundance, viz. Kr, Kr and Kr, Kr is prominent, whereas the intensity ratio of Kr to Kr shows a weak signature of it. The isotope anomaly tends to disappear with increasing oxygen mixing in the plasma. The observed trends in the intensities of the krypton isotopes do not follow the prediction of linear Landau wave damping in the plasma. Copyright © 2016 John Wiley & Sons, Ltd.

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“…Therefore, in the case of SECRAL, the buildup limit is about 7 W=cm 3 . Another explanation and understanding could be given by Ivanov in the article [83] which points out that with increasing the microwave power the electrons are heated more and more, resulting in an increase of the ionization coefficients; meanwhile, the confinement time of the plasma decreases due to ion heating and an increase of the turbulence enhanced plasma transport to the walls. At low power, the beneficial effect of electron heating dominates.…”

Section: E Microwave Frequency and Power Effectmentioning

confidence: 99%

“…Thus, increasing the admitted power improves the performance of an ion source. At a certain power level, the increase of plasma losses due to transport balances the improvement due to electron heating, outweighing it when increasing the admitted power further [83]. Some significant studies on these issues were also conducted by Gammino, Mascali, Koivisto and Lyneis [43,[84][85][86][87], which can be helpful for understanding the role of microwave coupling, effects of microwave frequency and power.…”

Section: E Microwave Frequency and Power Effectmentioning

confidence: 99%

Intense highly charged ion beam production and operation with a superconducting electron cyclotron resonance ion source

Zhao

Sun

Guo

et al. 2017

Phys. Rev. Accel. Beams

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The superconducting electron cyclotron resonance ion source with advanced design in Lanzhou (SECRAL) is a superconducting-magnet-based electron cyclotron resonance ion source (ECRIS) for the production of intense highly charged heavy ion beams. It is one of the best performing ECRISs worldwide and the first superconducting ECRIS built with an innovative magnet to generate a high strength minimum-B field for operation with heating microwaves up to 24-28 GHz. Since its commissioning in 2005, SECRAL has so far produced a good number of continuous wave intensity records of highly charged ion beams, in which recently the beam intensities of 40 Ar 12þ and 129 Xe 26þ have, for the first time, exceeded 1 emA produced by an ion source. Routine operations commenced in 2007 with the Heavy Ion accelerator Research Facility in Lanzhou (HIRFL), China. Up to June 2017, SECRAL has been providing more than 28,000 hours of highly charged heavy ion beams to the accelerator demonstrating its great capability and reliability. The great achievement of SECRAL is accumulation of numerous technical advancements, such as an innovative magnetic system and an efficient double-frequency (24 þ 18 GHz) heating with improved plasma stability. This article reviews the development of SECRAL and production of intense highly charged ion beams by SECRAL focusing on its unique magnet design, source commissioning, performance studies and enhancements, beam quality and long-term operation. SECRAL development and its performance studies representatively reflect the achievements and status of the present ECR ion source, as well as the ECRIS impacts on HIRFL.

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Ion confinement in electron cyclotron resonance ion sources (ECRIS): importance of nonlinear plasma-wave interaction

Cited by 32 publications

References 45 publications

Diagnostics of a charge breeder electron cyclotron resonance ion source helium plasma with the injection ofNa231+ions

Diagnostics of a charge breeder electron cyclotron resonance ion source helium plasma with the injection ofNa231+ions

Charge state distribution studies of pure and oxygen mixed krypton ECR plasma – signature of isotope anomaly and gas mixing effect

Intense highly charged ion beam production and operation with a superconducting electron cyclotron resonance ion source

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