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

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Presentation on theme: "Gennady Fiksel Robert Rosner UW Madison Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasma August 4-6, Madison, WI Anomalous."— Presentation transcript:

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

2 CMSO CMSO Meeting August 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.

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

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

5 CMSO CMSO Meeting August Madison WI MST - fast ion heating in during reconnection events Both impurities and majority components are rapidly heated. Stronger heating of heavy ions. TDTD T C4+ TeTe electrons Deuterium C 4+ Heating phase: Required heating power ~ 1MW/m 3 What can provide it? Cooling phase: Why so fast?

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

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

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

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

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

11 CMSO CMSO Meeting August Madison WI Comparison table MSTMRXSSXSolar corona T || / T 1??< 1 <<1 in wind V flow /V A small 1from <<1 to >> 1 T Z /T p 1??>> 1 Localization global. better resolution soon reconnection layer reconnection layer narrow regions in corona

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

13 CMSO CMSO Meeting August Madison WI 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 q wall < 0 Reversal surface removed q wall > 0

14 CMSO CMSO Meeting August Madison WI 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 q wall < 0 Reversal surface removed q wall > 0

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

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

17 CMSO CMSO Meeting August 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?

18 CMSO CMSO Meeting August 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 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 New Mach probe for local ion flow measurements 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

19 CMSO CMSO Meeting August Madison WI MST experimental plans Detailed accounting of ion energy balance - spatial profile of T i, T e, n e, radiation, and CX losses. Models of ion thermal transport. Isotropy of ion heating, Z and M dependence. Cross-correlation of T i with magnetic fluctuations in time and frequency domains, contribution from different modes. Local (edge) measurements of ion energy deposition 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.

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

21 CMSO CMSO Meeting August Madison WI SSX Study ion heating and flow generation in FRC-like equilibrium ion Doppler spectroscopy (with contribution from MST) single shot measurement of T i, v i (1 s resolution)

22 CMSO CMSO Meeting August 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.

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


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