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Anomalous Ion Heating Status and Research Plan

Anomalous Ion Heating Status and Research Plan. Gennady Fiksel Robert Rosner UW Madison Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasma August 4-6, Madison, WI. Preamble. Anomalous ion heating and/or acceleration is present in many laboratory and space plasmas.

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Anomalous Ion Heating Status and Research Plan

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  1. Anomalous Ion HeatingStatus and Research Plan Gennady Fiksel Robert Rosner UW Madison Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasma August 4-6, Madison, WI

  2. Preamble • Anomalous ion heating and/or acceleration is present in many laboratory and space plasmas. • There are no reliable and experimentally proved explanations of that. • There is definite correlation with magnetic reconnections and/or magnetic turbulence. • The goal is to understand the nature of ion heating and unravel the relation to magnetic turbulence and reconnection. CMSO Meeting • August 4-6 2004 • Madison WI

  3. Outline • Overview of results. Similarities and differences in different experiments/observations. • Ion heating and magnetic turbulence • Plans and progress. CMSO Meeting • August 4-6 2004 • Madison WI

  4. MST - anomalously high ion temperature observed It is expected that Ti /Te ≈ 0.1 based on the balance between collisional e/i heating and losses. CMSO Meeting • August 4-6 2004 • Madison WI

  5. Both impurities and majority components are rapidly heated. Stronger heating of heavy ions. C4+ electrons TD TC4+ Te Deuterium MST - fast ion heating in during reconnection events Heating phase: Required heating power ~ 1MW/m3 What can provide it? Cooling phase: Why so fast? CMSO Meeting • August 4-6 2004 • Madison WI

  6. T|| ≈ T MST - Ion heating is isotropic No fast Alfvenic flows were detected. Distribution function remains Maxwellian CMSO Meeting • August 4-6 2004 • Madison WI

  7. MRX - Enhanced ion heating inside reconnection region (Hsu et al. ‘00) CMSO Meeting • August 4-6 2004 • Madison WI

  8. Solar corona - strong heating of protons and heavy ions Heating is M and Z dependent CMSO Meeting • August 4-6 2004 • Madison WI

  9. Note the large anisotropy: TO/TO  10 Solar corona - strong flow, ion heating is anisotropic From: Cranmer et al., ApJ, 511, 481 (1998) CMSO Meeting • August 4-6 2004 • Madison WI

  10. SSX - Alfvenic flows and ion heating Ion energy distribution measured with electrostatic analyzers C. Cothran M. Brown Fit to a thermal distribution with drift: T=33±11eV and V=86±20eV CMSO Meeting • August 4-6 2004 • Madison WI

  11. Comparison table CMSO Meeting • August 4-6 2004 • Madison WI

  12. We do not know if the ion heating mechanism is the same or different in these cases Magnetic fluctuations and/or magnetic reconnection present in all cases and thought to be the main candidate for ion heating. CMSO Meeting • August 4-6 2004 • Madison WI

  13. Ion heating drastically decreases when reversal surface q=0 and edge resonant m=0 fluctuations are removed from plasma Reversal surface inside plasma qwall < 0 Reversal surface removed qwall > 0 MST - correlation of ion heating with active control of magnetic activity In improved confinement regimes with low magnetic fluctuations the “anomalous” contribution to ion heating decreases. CMSO Meeting • August 4-6 2004 • Madison WI

  14. Ion heating drastically decreases when reversal surface q=0 and edge resonant m=0 fluctuations are removed from plasma Reversal surface inside plasma qwall < 0 Reversal surface removed qwall > 0 MST - correlation of ion heating with active control of magnetic activity In improved confinement regimes with low magnetic fluctuations the “anomalous” contribution to ion heating decreases. CMSO Meeting • August 4-6 2004 • Madison WI

  15. MRX - Broad spectra of magnetic turbulence CMSO Meeting • August 4-6 2004 • Madison WI

  16. Frequency (Hz) Solar distance (units of RS) Solar magnetic turbulence Wave frequencies vary extremely widely in the outflowing solar wind CMSO Meeting • August 4-6 2004 • Madison WI

  17. Questions • What is the free energy source? • What is relation between ion heating and reconnections? • Viscous damping of reconnection flows or fluctuation induced heating? • What fluctuations are responsible for ion accelerating and heating and what is the absorption mechanism? • Energy flow from the energy source into fluctuations - direct excitation or non-linear cascade? • Ion heating in different lab/space plasma - manifestation of the same mechanism? CMSO Meeting • August 4-6 2004 • Madison WI

  18. Existing diagnostics • RS - Rutherford scattering diagnostic - local measurements of majority ion temperature. • IDS - passive Ion Doppler Spectroscopy - chord averaged ion impurities temperature and flow. • Thomson scattering - Te Commissioned and upgraded since the last CSMO meeting • Upgraded CHERS - active Doppler spectroscopy. Ion impurities temperature and flow. Good spatial (few cm) and temporal (10 usec) resolution. • New high resolution, high frequency magnetic fluctuation probes MST diagnostic set Coming online very soon • New Diagnostic Neutral Beam for CHERS - longer pulse, higher energy • New insertable probes for local ion Doppler spectroscopy • New probe for local measurements of ion energy deposition <JiE> • New Mach probe for local ion flow measurements CMSO Meeting • August 4-6 2004 • Madison WI

  19. MST experimental plans • Detailed accounting of ion energy balance - spatial profile of Ti, Te, ne, radiation, and CX losses. Models of ion thermal transport. • Isotropy of ion heating, Z and M dependence. • Cross-correlation of Ti with magnetic fluctuations in time and frequency domains, contribution from different modes. • Local (edge) measurements of ion energy deposition <JiE> • Local measurements of ion flows and evaluation of ion viscous heating - cross with the flow and momentum group. • Active control of magnetic activity. • Active ion heating from externally driven E. CMSO Meeting • August 4-6 2004 • Madison WI

  20. MRX Newly upgraded MRX has expanded operation regimes to study ion heating, such as more collisionless or larger S plasmas. CMSO Meeting • August 4-6 2004 • Madison WI

  21. SSX • Study ion heating and flow generation in FRC-like equilibrium • ion Doppler spectroscopy (with contribution from MST) • single shot measurement of Ti, vi (1 s resolution) CMSO Meeting • August 4-6 2004 • Madison WI

  22. Theory plans • Ion acceleration by E field - effect of impurities, mirror trapping, stochastic magnetic field, and magnetic islands. • Dielectric tensor for ion heating from tearing modes. • Viscous heating by compression tearing modes. • Ion heating in self consistent streaming electron emission theory • Cascade processes to generate small-scale/high-frequencies. Assessment of Alfven cascades. • Ion and electron heating via Alfven cascades. • 2-fluid Nimrod study of ion heating from reconnection. • PIC simulation of ion heating from reconnection. CMSO Meeting • August 4-6 2004 • Madison WI

  23. Solar corona and astrophysics Bob Rosner - next CMSO Meeting • August 4-6 2004 • Madison WI

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