6533b7d0fe1ef96bd125a4e0
RESEARCH PRODUCT
Limitations of electron cyclotron resonance ion source performances set by kinetic plasma instabilities.
Vadim SkalygaIvan IzotovRisto KronholmJ. KomppulaJanne LaulainenOlli TarvainenTaneli KalvasDmitry MansfeldHannu Koivistosubject
Physicsta114Waves in plasmasCyclotronPlasmaElectronelectron cyclotron resonance ion sourceElectron cyclotron resonanceIon sourcelaw.inventionlawPhysics::Plasma PhysicsElectromagnetic electron waveAtomic physicsInstrumentationPlasma stabilitykinetic plasma instabilitiesdescription
Electron cyclotron resonance ion source (ECRIS) plasmas are prone to kinetic instabilities due to anisotropy of the electron energy distribution function stemming from the resonant nature of the electron heating process. Electron cyclotron plasma instabilities are related to non-linear interaction between plasma waves and energetic electrons resulting to strong microwave emission and a burst of energetic electrons escaping the plasma, and explain the periodic oscillations of the extracted beam currents observed in several laboratories. It is demonstrated with a minimum-B 14 GHz ECRIS operating on helium, oxygen, and argon plasmas that kinetic instabilities restrict the parameter space available for the optimization of high charge state ion currents. The most critical parameter in terms of plasma stability is the strength of the solenoid magnetic field. It is demonstrated that due to the instabilities the optimum Bmin-field in single frequency heating mode is often ≤ 0.8BECR, which is the value suggested by the semiempirical scaling laws guiding the design of modern ECRISs. It is argued that the effect can be attributed not only to the absolute magnitude of the magnetic field but also to the variation of the average magnetic field gradient on the resonance surface. peerReviewed
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2015-01-01 | The Review of scientific instruments |