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Anomalous Ion Heating Status and Research Plan

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1 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

2 CMSO Meeting • August 4-6 2004 • Madison WI
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 • Madison WI

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

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

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

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

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

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

11 Comparison table MST MRX SSX Solar corona T|| / T ≈1 ? < 1
<<1 in wind Vflow/VA small ≈ 1 from <<1 to >> 1 TZ/Tp ≥1 >> 1 Localization global. better resolution soon reconnection layer reconnection layer narrow regions in corona CMSO Meeting • August • Madison WI

12 CMSO Meeting • August 4-6 2004 • Madison WI
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 • Madison WI

13 In improved confinement regimes with low magnetic fluctuations
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. 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 removed qwall > 0 CMSO Meeting • August • Madison WI

14 In improved confinement regimes with low magnetic fluctuations
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. 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 removed qwall > 0 CMSO Meeting • August • Madison WI

15 MRX - Broad spectra of magnetic turbulence
CMSO Meeting • August • Madison WI

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

17 CMSO Meeting • August 4-6 2004 • Madison WI
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 • Madison WI

18 CMSO Meeting • August 4-6 2004 • Madison WI
MST diagnostic set 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 Existing diagnostics 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 Commissioned and upgraded since the last CSMO meeting 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 • 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 • Madison WI

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

21 CMSO Meeting • August 4-6 2004 • Madison WI
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 • Madison WI

22 CMSO Meeting • August 4-6 2004 • Madison WI
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 • Madison WI

23 Solar corona and astrophysics
Bob Rosner - next CMSO Meeting • August • Madison WI

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