Observations of an Ion-Driven Instability in Non-Neutral Plasmas Confined on Magnetic Surfaces
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)
- Kyoto Institute of Technology, Department of Electronics, Matsugasaki, Kyoto 606-8585 (Japan)
The first detailed experimental study of an instability driven by the presence of a finite ion fraction in an electron-rich non-neutral plasma confined on magnetic surfaces is presented. The instability has a poloidal mode number m=1, implying that the parallel force balance of the electron fluid is broken and that the instability involves rotation of the entire plasma, equivalent to ion-resonant instabilities in Penning traps and toroidal field traps. The mode appears when the ion density exceeds approximately 10% of the electron density. The measured frequency decreases with increasing magnetic field strength, and increases with increasing radial electric field, showing that the instability is linked to the ExB flow of the electron plasma. The frequency does not, however, scale exactly with E/B, and it depends on the ion species that is introduced, implying that the instability consists of interacting perturbations of ions and electrons.
- OSTI ID:
- 21024765
- Journal Information:
- Physical Review Letters, Vol. 100, Issue 6; Other Information: DOI: 10.1103/PhysRevLett.100.065002; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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