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Experimental Studies of the Hall Effect in MRX

Experimental Studies of the Hall Effect in MRX. Y. Ren, S. Gerhardt , A. Kuritsyn, H. Ji, R. Kulsrud, M. Yamada Princeton Plasma Physics Laboratory. Outline. The Hall effect in numerical simulation and space observations.

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Experimental Studies of the Hall Effect in MRX

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  1. Experimental Studies of the Hall Effect in MRX Y. Ren, S. Gerhardt , A. Kuritsyn, H. Ji, R. Kulsrud, M. Yamada Princeton Plasma Physics Laboratory

  2. Outline • The Hall effect in numerical simulation and space observations. • Experimental study of the Hall effects during magnetic reconnection in the MRX. • Summary

  3. Magnetic Reconnection in Space and Laboratory

  4. Two Models to Fast Magnetic Reconnection Two-fluid MHD model in which electrons and ions decouple within the scale of order c/pi and the reconnection rate is enhanced by the dispersive nature of the whistler wave. Generalized Sweet-Parker model with anomalous resistivity.

  5. The Hall Effects During Reconnection Shown in 2D Simulations P. L. Pritchett, JGR 2001 The out-of-plane magnetic field is generated during reconnection. Different motions of ions and electrons show the decoupling of them, thus generating the in-plane Hall current and the out-of-plane magnetic field.

  6. Space observation showing signs of the Hall effects F.S. Mozer et al., P.R.L. 2002 The out-of-plane magnetic field.

  7. Can the Hall effects be observed in a laboratory plasma?

  8. MRX-Upgraded

  9. Experimental Setup

  10. 90-channel Probe Array Scan( R=1cm,  Z=4cm) Y. Ren et al., PRL 2005

  11. Comparison with numerical simulation (I) 4.8 c/pi 0.9 c/pi Pritchett, JGR , 2001

  12. Fine structure probe array • A magnetic probe array with spatial resolution up to 1.25 mm and 71 channels is used to search for the signs of the Hall effects. Fine structure probe

  13. The Construction of the Fine Structure Probe (I) D. Cylinder The coils are hand-winded with 48 AWG magnet wire to 160 turns and approximately 1mm in diameter and 2 mm in length. The small coils are glued to an alumina rod.

  14. The Construction of the Fine Structure Probe (II) Fine structure probe Aluminized mylar is used to provide electrostatic shielding. The 3dB point of the frequency response is about 1MHz.

  15. The probe location • The fine structure probe is inserted in the radial direction in the MRX at two locations, Z=7cm and Z=-7cm, are extensively studied. 71-channel magnetic probe array

  16. The toroidal field reversal is found in both locations (1) (2) (3)

  17. Comparison with numerical simulation (II) Pritchett, JGR , 2001 71-channel probe location Electron (1) VZe/VA» 0.7 (underestimate VZe) 1.8 c/pi (2) Ve/VA» 1.2 in numerical simulation Ion

  18. The Effect of collisionality on the Hall Effect Working gas: D2

  19. Quadrupole field in Argon Plasma Fill pressure 2.1 mTor. ~0.3, ~9 ~14 cm, assuming Z=1

  20. Summary • The Hall effects are observed during magnetic reconnection in MRX. Good agreement is found between experiment and simulation. • The future goal is to study the relation between the Hall effect and fluctuations and to study the quadrupole field with fine magnetic probe array.

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