The first results with the new JYFL 14 GHz ECR ion source

Koivisto, H.; Heikkinen, Pauli; HäNninen, VäInö; Lassila, Antti; Leinonen, H; Nieminen, V.; Pakarinen, J.; Ranttila, K.; Ärje, J.; Liukkonen, E.

doi:10.1016/s0168-583x(00)00615-7

Cited by 66 publications

(50 citation statements)

References 3 publications

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“…The experimental data demonstrating that the instabilities limit the tuning range available for the optimization of the extracted currents of high charge state ions in cw operation were taken with the A-ECR type JYFL 14 GHz ECRIS 14 equipped with two solenoid coils, permanent magnet sextupole, and aluminum plasma chamber. The magnetic field strength can be adjusted by varying the solenoid coil currents, which affects the injection and extraction mirror ratios as well as the B-minimum.…”

Section: Experimental Setup and Resultsmentioning

confidence: 99%

Limitation of the ECRIS performance by kinetic plasma instabilities (invited)

Tarvainen

Kalvas

Koivisto

et al. 2015

Review of Scientific Instruments

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Limitation of the ECRIS performance by kinetic plasma instabilities (invited)Tarvainen, Olli; Kalvas, Taneli; Koivisto, Hannu; Komppula, Jani; Kronholm, Risto; Laulainen, Janne; Izotov, I.; Mansfeld, D.; Skalyga, V.; Toivanen, V.; Machicoane, G.Tarvainen, O., Kalvas, T., Koivisto, H., Komppula, J., Kronholm, R., Laulainen, J., . . . Machicoane, G. (2016 Electron cyclotron resonance ion source (ECRIS) plasmas are prone to kinetic instabilities due to anisotropic electron velocity distribution. The instabilities are associated with strong microwave emission and periodic bursts of energetic electrons escaping the magnetic confinement. The instabilities explain the periodic ms-scale oscillation of the extracted beam current observed with several high performance ECRISs and restrict the parameter space available for the optimization of extracted beam currents of highly charged ions. Experiments with the JYFL 14 GHz ECRIS have demonstrated that due to the instabilities the optimum B min -field is less than 0.8B ECR , which is the value suggested by the semiempirical scaling laws guiding the design of ECRISs. C 2015 AIP Publishing LLC. [http://dx

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Section: Experimental Setup and Resultsmentioning

confidence: 99%

Limitation of the ECRIS performance by kinetic plasma instabilities (invited)

Tarvainen

Kalvas

Koivisto

et al. 2015

Review of Scientific Instruments

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“…The experimental data were taken with the roomtemperature A-ECR-U type JYFL 14 GHz ECRIS 23 operated with a single frequency (14.056 GHz) sustaining the plasma in the continuous (CW) mode. In the experiments described here, a klystron amplifier providing the microwave signal was connected to a WR-62 waveguide port of the ion source.…”

Section: Methodsmentioning

confidence: 99%

Broadband microwave emission spectrum associated with kinetic instabilities in minimum-B ECR plasmas

et al. 2017

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Izotov, I.; Kalvas, Taneli; Koivisto, Hannu; Kronholm, Risto; Mansfeld, D.; Skalyga, V.; Tarvainen, Olli Izotov, I., Kalvas, T., Koivisto, H., Kronholm, R., Mansfeld, D., Skalyga, V., & Tarvainen, O. (2017). Broadband microwave emission spectrum associated with kinetic instabilities in minimum-B ECR plasmas. Physics of Plasmas, 24 (4) Plasmas of electron cyclotron resonance ion sources (ECRISs) are prone to kinetic instabilities due to the resonant heating mechanism resulting in anisotropic electron velocity distribution.Frequently observed periodic oscillations of extracted ion beam current in the case of high plasma heating power and/or strong magnetic field have been proven to be caused by cyclotrontype instabilities leading to a notable reduction and temporal variation of highly charged ion production. Thus, investigations of such instabilities and techniques for their suppression have become important topics in ECRIS research. The microwave emission caused by the instabilities contains information on the electron energy distribution and growth mechanism of the instability. The emission has been studied earlier in the frequency range of 8-14 GHz allowing us to deduce the probable excited mode. A more detailed study of the microwave emission spectrum of a minimum-B ECR plasma, sustained by 14 GHz microwave radiation, is presented in this work. It was found that the frequencies of the microwaves emitted by the plasma consist of several harmonics of the main band and extend from 6 GHz up to 25 GHz, being independent of the plasma parameters. Published by AIP Publishing.[http://dx

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“…8 The plasma was heated by a klystron amplifier at the frequency of 14 GHz. The klystron was operated in a pulsed mode by controlling the low-power input signal from an oscillator with a fast RF-switch with a rise/fall time of 40/100 ns.…”

Section: Methodsmentioning

confidence: 99%

Cyclotron instability in the afterglow mode of minimum-B ECRIS

Izotov

Kalvas

Koivisto

et al. 2015

Review of Scientific Instruments

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It was shown recently that cyclotron instability in non-equilibrium plasma of a minimum-B electron cyclotron resonance ion source (ECRIS) causes perturbation of the extracted ion current and generation of strong bursts of bremsstrahlung emission, which limit the performance of the ion source. The present work is devoted to the dynamic regimes of plasma instability in ECRIS operated in pulsed mode. Instability develops in decaying plasma shortly after heating microwaves are switched off and manifests itself in the form of powerful pulses of electromagnetic emission associated with precipitation of high energy electrons. Time-resolved measurements of microwave emission bursts are presented. It was found that even in various gases (helium and oxygen were studied) and at different values of magnetic field and heating power, the dynamic spectra demonstrate common features: decreasing frequency within a single burst as well as from one burst to another.

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The first results with the new JYFL 14 GHz ECR ion source

Cited by 66 publications

References 3 publications

Limitation of the ECRIS performance by kinetic plasma instabilities (invited)

Limitation of the ECRIS performance by kinetic plasma instabilities (invited)

Broadband microwave emission spectrum associated with kinetic instabilities in minimum-B ECR plasmas

Cyclotron instability in the afterglow mode of minimum-B ECRIS

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