Suppression of cyclotron instability in Electron Cyclotron Resonance ion sources by two-frequency heating

Multiple frequency heating is one of the most effective techniques to improve the performance of Electron Cyclotron Resonance (ECR) ion sources. The method increases the beam current and average charge state of the extracted ions and enhances the temporal stability of the ion beams. It is demonstrated in this paper that the stabilizing effect of two-frequency heating is connected with the suppression of electron cyclotron instability. Experimental data show that the interaction between the secondary microwave radiation and the hot electron component of ECR ion source plasmas plays a crucial role in mitigation of the instabilities.

[1]  R. Geller.  ECRIS: The Electron Cyclotron Resonance Ion Sources , 1990 .

[2]  M. Kase,et al.  Effect of minimum strength of mirror magnetic field (Bmin) on production of highly charged heavy ions from RIKEN liquid-He-free super conducting electron–cyclotron resonance ion source (RAMSES) , 2002 .

[3]  D. Leitner,et al.  Next generation ECR ion sources: First results of the superconducting 28 GHz ECRIS – VENUS , 2005 .

[4]  B. Hafizi,et al.  Relativistic electron motion in the presence of cyclotron resonant electromagnetic waves , 1987 .

[5]  S. Golubev,et al.  Cyclotron-resonance maser with adiabatic magnetic pumping in a low-density plasma , 2007 .

[6]  D. Leitner,et al.  Status report of the 28 GHz superconducting electron cyclotron resonance ion source VENUS (invited) , 2006 .

[7]  O. Tarvainen,et al.  Electron cyclotron resonance ion source related development work for heavy-ion irradiation tests , 2006 .

[8]  A. Drentje.  The ECR ion source and associated equipment at the KVI , 1985 .

[9]  D. Mansfeld,et al.  Beam current oscillations driven by cyclotron instabilities in a minimum-B electron cyclotron resonance ion source plasma , 2014 .

[10]  L. Celona,et al.  Results and interpretation of high frequency experiments at 28 GHz in ECR ion sources, future prospects , 2002 .

[11]  L Celona,et al.  Observations of the frequency tuning effect in the 14 GHz CAPRICE ion source. , 2008, The Review of scientific instruments.

[12]  D. Mansfeld,et al.  Microwave emission related to cyclotron instabilities in a minimum-B electron cyclotron resonance ion source plasma , 2015 .

[13]  G. G. Denisov,et al.  CW Ka-Band Kilowatt-Level Helical-Waveguide Gyro-TWT , 2012, IEEE Transactions on Electron Devices.

[14]  D. Mansfeld,et al.  Limitations of electron cyclotron resonance ion source performances set by kinetic plasma instabilities. , 2015, The Review of scientific instruments.

[15]  J. Ärje,et al.  The first results with the new JYFL 14 GHz ECR ion source , 2001 .