Presentation is loading. Please wait.

Presentation is loading. Please wait.

Weixing Ding University of California, Los Angeles,USA collaborators: D.L. Brower, W. Bergerson, D. Craig, D. Demers, G.Fiksel, D.J. Den Hartog, J. Reusch,

Published byEdith Barnett Modified over 9 years ago

Similar presentations

Presentation on theme: "Weixing Ding University of California, Los Angeles,USA collaborators: D.L. Brower, W. Bergerson, D. Craig, D. Demers, G.Fiksel, D.J. Den Hartog, J. Reusch,"— Presentation transcript:

1 Weixing Ding University of California, Los Angeles,USA collaborators: D.L. Brower, W. Bergerson, D. Craig, D. Demers, G.Fiksel, D.J. Den Hartog, J. Reusch, S. C. Prager, J. Sarff, T.Yates and MST team (Oct. 14, 2009 Princeton) Particle Transport due to Stochastic Magnetic Field in a High-Temperature Plasma

2 Introduction Free energy instabilities Fluctuations Particle (charge) Momentum Energy Transport  J // (r) Tearing

3 Electron Density Relaxation Due to Magnetic Field Perturbation Magnetic Field Fluctuations Driven by Tearing Instabilities in MST MST L.Zeng (UCLA) et al DIII-D by reflectometry Driven by I-coil externally in DIII-D DIII-D

4 MST Reversed-Field Pinch (RFP) is toroidal configuration with relatively weak toroidal magnetic field B T ( i.e., B T ~ B p ) Madison Symmetric Torus For plasma w/o current profile control R 0 = 1.5 m, a = 0.51 m, I p ~400 kA B T ~ 3-4 kG, n e ~ 10 19 m -3,T e ~T i ~300eV  ~7%

5 Fluctuations and Transport in the MST Generation of magnetic flux (dynamo) Particle and energy transport Ion heating Momentum transport Magnetic reconnection events

6 Outline (1) Density Relaxation and particle transport during reconnection; (2) Measured magnetic fluctuation-induced particle flux accounts for particle transport; GOAL: Identify the role of stochastic magnetic field in particle transport during reconnection

7 Particle Diffusion Rate in a Stochastic Magnetic Field in MST Toroidal Angle /  r/a Puncture Plot of B Field in MST Magnetic diffusivity coefficient from field line tracing (Hudson and Gennady, 2006) Rechester & Rosenbluth (1978) derived a quasi-linear coefficient Harvey (1981) and Finn (1990) suggest particle diffusion rate D i ~ D m c s (or V i,th ) Plugging in MST parameters:  p ~ 1-2 ms (quasi-linear estimate) in ambient case  p ~ 0.1-0.2 ms (experiment) during relaxation event

8 Measured Total Particle Flux during Reconnection r L Total particle flux surges to 1.5*10 21 m -2 s -1 during reconnection

9 Fluctuation-Induced Particle Flux Contributes to Total Flux Particle transport is determined by perpendicular momentum balance Particle transport arises from particle streaming along stochastic field lines total flux pinch electrostatic magnetic fluctuation

10 Pinch and electrostatic fluctuation-induced particle flux are negligible Lei, et al. PRL 2002 total flux pinch electrostatic magnetic fluctuation electrostatic

11 Magnetic Fluctuation-Induced Particle Flux Density-fluctuation dependent flux Velocity-fluctuation dependent flux

12 Measurement of Magnetic Fluctuation-Induced Particle Flux Laser Faraday rotation B  Laser Faraday rotation Laser interferometer ( ) Motion Stark effect CHERS, Mode Rotation, Ion Doppler Spectroscopy Not measured, inferred from quasi-neutrality 7 independent quantities are needed to determine electron and ion flux

13 FIR Polarimeter-Interferometer System MST Interferometer density fluctuation Faraday rotation magnetic field 11 chords, separation 8 cm,phase resolution 0.05 degree, time response up to 1  s Ding, Brower, et al PRL(2003),(2004) RSI(2004),(2008) See poster: P03-23(Bergerson)

14 Measurement of Equilibrium Magnetic Field and Current Denisty Time [ms] By Motion Stark Effect By Faraday rotation

15 Measurement of density and magnetic fluctuation Density fluctuations Radial Magnetic fluctuations m/n=1/6

16 Magnetic fluctuation-induced electron particle flux (Total Flux) Density fluctuation contributes to electron particle flux

17 Magnetic fluctuation-induced ion particle flux 1.50 0.75 Den Hartog et. Al,PoP,1999 (Ion Flux) Velocity fluctuation contributes to ion flux

18 Magnetic Fluctuation Induced Flux Balances the Change of Density Integrating over time Magnetic fluctuation induced particle transport drives density change

19 1.50 0.75 Electron and ion flux arise from different mechanism Electron flux Ion flux Total flux

20 (m,n) are poloidal and toroidal mode number Ambipolarity of Particle Transport (difference between electron and ion particle flux) Ding, et al. PRL 2007

21 Particle diffusivity is (30X) larger than QL prediction Rechester&Rosenbluth(1978) (without ambipolarity ) ~~ (30 times) Predicted Particle Transport ~Predicted Heat Transport Experimentally, particle diffusion rate is approximately electron diffusion rate in a stochastic magnetic field. Harvey (1981) (with ambipolariy)

22 Summary (1)Rapid particle transport is observed in MST associated with the stochastic field; (2) Electron particle flux is comparable to ion flux ( ), accounting for global density change during a reconnection event; (3) Particle transport is much larger than the expected from quasi-linear theory.

23 Magnetic Fluctuation Measurement Method Plasma X 1 X 2 Ding, et al. PRL (2003)

24 Localization of Density Fluctuations Physically

Download ppt "Weixing Ding University of California, Los Angeles,USA collaborators: D.L. Brower, W. Bergerson, D. Craig, D. Demers, G.Fiksel, D.J. Den Hartog, J. Reusch,"

Similar presentations

NSF Site Visit Madison, May 1-2, 2006 Magnetic Helicity Conservation and Transport R. Kulsrud and H. Ji for participants of the Center for Magnetic Self-organization.

NSF Site Visit Madison, May 1-2, 2006 Magnetic Helicity Conservation and Transport R. Kulsrud and H. Ji for participants of the Center for Magnetic Self-organization.
Statistical Properties of Broadband Magnetic Turbulence in the Reversed Field Pinch John Sarff D. Craig, L. Frassinetti 1, L. Marrelli 1, P. Martin 1,

Statistical Properties of Broadband Magnetic Turbulence in the Reversed Field Pinch John Sarff D. Craig, L. Frassinetti 1, L. Marrelli 1, P. Martin 1,
Experimental Measurements of Non- MHD Dynamo Effects Summarized by S.C. Prager.

Experimental Measurements of Non- MHD Dynamo Effects Summarized by S.C. Prager.
Dynamo Effects in Laboratory Plasmas S.C. Prager University of Wisconsin October, 2003.

Dynamo Effects in Laboratory Plasmas S.C. Prager University of Wisconsin October, 2003.
Self-consistent mean field forces in two-fluid models of turbulent plasmas C. C. Hegna University of Wisconsin Madison, WI Hall Dynamo Get-together PPPL.

Self-consistent mean field forces in two-fluid models of turbulent plasmas C. C. Hegna University of Wisconsin Madison, WI Hall Dynamo Get-together PPPL.
Magnetic Relaxation in MST S. Prager University of Wisconsin and CMSO.

Magnetic Relaxation in MST S. Prager University of Wisconsin and CMSO.
Control of Magnetic Chaos & Self-Organization John Sarff for MST Group CMSO General Meeting Madison, WI August 4-6, 2004.

Control of Magnetic Chaos & Self-Organization John Sarff for MST Group CMSO General Meeting Madison, WI August 4-6, 2004.
Plans for Dynamo Research Presented by F. Cattaneo, S. Prager.

Plans for Dynamo Research Presented by F. Cattaneo, S. Prager.
Progress and Plans on Magnetic Reconnection for CMSO For NSF Site-Visit for CMSO May1-2, 2005 1. Experimental progress [M. Yamada] -Findings on two-fluid.

Progress and Plans on Magnetic Reconnection for CMSO For NSF Site-Visit for CMSO May1-2, Experimental progress [M. Yamada] -Findings on two-fluid.
Ion Heating and Velocity Fluctuation Measurements in MST Sanjay Gangadhara, Darren Craig, David Ennis, Gennady Fiskel and the MST team University of Wisconsin-Madison.

Ion Heating and Velocity Fluctuation Measurements in MST Sanjay Gangadhara, Darren Craig, David Ennis, Gennady Fiskel and the MST team University of Wisconsin-Madison.
Self-consistent mean field forces in two-fluid models of turbulent plasmas C. C. Hegna University of Wisconsin Madison, WI CMSO Meeting Madison, WI August.

Self-consistent mean field forces in two-fluid models of turbulent plasmas C. C. Hegna University of Wisconsin Madison, WI CMSO Meeting Madison, WI August.
Experimental Tests of Two-Fluid Relaxation D. Craig and MST Team University of Wisconsin – Madison General Meeting of the Center for Magnetic Self-Organization.

Experimental Tests of Two-Fluid Relaxation D. Craig and MST Team University of Wisconsin – Madison General Meeting of the Center for Magnetic Self-Organization.
Dynamo and Magnetic Helicity Flux Hantao Ji CMSO & PPPL CMSO General Meeting Princeton, October 5-7, 2005 Contributors: Eric Blackman (Rochester) Stewart.

Dynamo and Magnetic Helicity Flux Hantao Ji CMSO & PPPL CMSO General Meeting Princeton, October 5-7, 2005 Contributors: Eric Blackman (Rochester) Stewart.
Comparing classical and lab plasma dynamos S. Prager University of Wisconsin useful discussions with D. Craig, H. Ji, J. Sarff, E. Zweibel.

Comparing classical and lab plasma dynamos S. Prager University of Wisconsin useful discussions with D. Craig, H. Ji, J. Sarff, E. Zweibel.
Multiple reconnections and explosive events and in MST and solar flares Gennady Fiksel CMSO workshop, Princeton, NJ, Oct 5-8, 2005.

Multiple reconnections and explosive events and in MST and solar flares Gennady Fiksel CMSO workshop, Princeton, NJ, Oct 5-8, 2005.
MHD Dynamos in the Lab and Dynamos Beyond MHD. The lab plasma dynamo does Generate current locally Increase toroidal magnetic flux Conserve magnetic helicity.

MHD Dynamos in the Lab and Dynamos Beyond MHD. The lab plasma dynamo does Generate current locally Increase toroidal magnetic flux Conserve magnetic helicity.
Anomalous Ion Heating Status and Research Plan

Anomalous Ion Heating Status and Research Plan
Some New Data From FRC Experiment on Relaxation For discussions at Hall-Dynamo and Related Physics meeting CMSO June 10-11, 2004 at PPPL Guo et al, PRL.

Some New Data From FRC Experiment on Relaxation For discussions at Hall-Dynamo and Related Physics meeting CMSO June 10-11, 2004 at PPPL Guo et al, PRL.
Charge-Exchange Spectroscopy at the University of Wisconsin-Madison Mark Nornberg Santhosh Kumar, Daniel Den Hartog Alexis Briesemeister 2012 ADAS Workshop.

Charge-Exchange Spectroscopy at the University of Wisconsin-Madison Mark Nornberg Santhosh Kumar, Daniel Den Hartog Alexis Briesemeister 2012 ADAS Workshop.
The UW Plasma Physics Group Clint Sprott, Paul Terry, Ellen Zweibel, Stas Boldyrev, Dalton Schnack, Cary Forest, Stewart Prager Presented to Introductory.

The UW Plasma Physics Group Clint Sprott, Paul Terry, Ellen Zweibel, Stas Boldyrev, Dalton Schnack, Cary Forest, Stewart Prager Presented to Introductory.

Similar presentations

Ads by Google