1 / 27

280 likes | 459 Vues

Pull Merging. R=0.15-0.22m. ,. R/a=1.6. B. ~.5kG. ,. T. =10-100eV. ,. i. 0. T. =20-30eV. ,. e. Push Merging. j'. 20. t. n. =0.5-1. 1. 0 m. -. 3. . e. j. t. j. t.

Télécharger la présentation
## Electrodes

**An Image/Link below is provided (as is) to download presentation**
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.
Content is provided to you AS IS for your information and personal use only.
Download presentation by click this link.
While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

**Pull Merging**R=0.15-0.22m , R/a=1.6 B ~.5kG , T =10-100eV , i 0 T =20-30eV , e Push Merging j' 20 t n =0.5-1. 1 0 m - 3 e j t j t Impulsive and Transient Magnetic Reconnection in TS-3 and TS-4 Merging ExperimentsY. Ono, T. Hayashi, M. Inomoto, C. Z. Frank Cheng Graduate School of Frontier Sciences, University of Tokyo, Tokyo E F Coils Separation Coils 2- D Magnetic Probe Array Electrostatic Probe Torus/OH coil r z CO2 Laser Interferometer PF Coils Electrodes Polychromator**"Close**d Current , Open Flux" "Close d Current , Close d Flux" Close MRX('95~) VTF('00~) Sheet Current Electrode Sheet Current hole Merging Experiments for Magnetic Reconnection Open Flux d Flux Internal Coil Sheet Current Close d Current TS-3('86~) , TS-4('00~), , SSX, Swift-FR C ('01~) , TS-5(UTST ‘05?) Open Current "Open " Exp. Type Caltech Exp.('98~) SS X ('96~) "Open Current , Close d Flux" Electrode**Pull Merging Experiment**Push Merging Experiment Impulsive and Transient Magnetic Reconnection in TS-3 and TS-4 Merging ExperimentsY. Ono, T. Hayashi, M. Inomoto, C. Z. Frank Cheng Graduate School of Frontier Sciences, University of Tokyo, Tokyo Operation: Magnetic Reconnection Exp. High-ß FRC/ ST Formation Boundary Exp. of CT/ST/RFP**Theory&**Simulation Major four researches have advantages and disadvantagesCollaboration among four fields Magnetosphere Observation Solar Observation Laboratory Experiment**CONTENTS**● High-power reconnection heating for fusion plasma startup (for Fusion Application) TS-3/4 ● Transition from steady rec. through transient one to sheet ejection (for Space/ Solar Study) [1] Impulsive sheet ejection: Push Merging:TS-3/4, in low resistivity/ high inflow. exp MAST from private to common flux, pileup & ejection [2]Mass pileup in high inflow exp. [3] Quasi-steady rec. in low inflow merging exp. [1’] Impulsive plasmoid ejection:Pull Merging:TS-4 from common to private flux, pileup & ejection**High-power reconnection heating for startup of fusion**plasmas Most of ion heating energy is confined by thick closed flux around X-point.**Second-Stable ST with Absolute Minimum-B**High-ß ST by merging Low-ß ST w/o merging Comparison with Troyon ScalingST merging :ßN<10C: 1st stableD: unstableCounterhelicity Merging: ßN<20A: 2nd stableB: unstable**Question Can the reconnection heat plasmas under high**guide field Bt? = How can we have high reconnection (outflow) speed when >>i?**jt [MA/m2]**Effective resistivity (E/j) of current sheet increases significantlywhen is compressed shorter than ri. (no correlation with c/pi). • : thickness**Sheet Ejection**3 150 Sheet Ejection B /B =0.5 B /B =2.2 //0 t t //0 V 2 B /B =1.0 B /B =2.7 B r //0 //0 t t z m] B /B =1.6 B /B =3.2 t //0 t //0 100 W 1 [m before (b) (t) reconnection 0 50 0 1 2 3 4 5 6 h X [ / ](t) d r i Large Bt B 0 z -1 0 1 2 3 4 5 6 Ejection .3 Anomalous Resistivity(d<ri) g´10[sec-1] Transition to intermittent reconnection increases averaged rec. speed as well as Ti significantly. .2 (a) .1 after reconnection Ti [eV] Bt0/B// large ri Reconnection rate as a function of Bx**Current-Sheet Ejection**(a) High inflow reconnection (b) Low inflow reconnection Compression**Compression**Multiple current-sheet ejections are composed of pileup and ejection. Inward Compression Reconnected flux ratio [%] ejection [1] Rec. from private flux to common flux**jt [MA/m ]**2 [A] Quasi-Steady Reconnection [B] Transient Reconnection [C] Intermittent Reconnection Slow inflow causes the quasi-steady reconnection. Quasi-Steady Phase Formation Phase Quasi-Steady Decay Formation Inflow Outflow 0 2 4 6 8 10 12 Time[µsec]**jt [MA/m ]**2 [A] Quasi-Steady Reconnection [B] Transient Reconnection [C] Intermittent Reconnection Fast inflow causes the mass pile-up inside the sheet, transforming the steady rec. to the transient rec. Transient (Formation) Pileup VinL, Voutd [m2sec-1]**Uniform Compression**[A] Quasi-Steady Rec. [B] Transient Rec. [C] Intermittent Rec. 500 400 300 V L in 200 V d out 100 0 0 2 4 6 8 10 12 jt [MA/m ] 2 Further increase in inflow causes significant pileup in the sheet and the mass ejection. Compression Quasi-Steady Phase Transient (Formation) ejection Inflow Pileup /sec] /sec] 2 2 Outflow [m L [m d out in V V Time [µsec]**5**-3 4 10 [m ] 19 3 ｴ 2 n 1 5 -3 4 10 [m ] 19 3 ｴ 2 n 1 5 -3 4 10 [m ] 19 3 ｴ 2 n 1 0.2 0.1 0.3 R [m] Evidence of density pileup and mass ejection t=194µsec t=196µsec t=174ｵsec t=176ｵsec 0 t=195µsec t=175ｵsec t=177ｵsec t=197µsec n (density) V r 0 Double-peaked profile! t=196µsec t=198µsec t=178ｵsec t=176ｵsec 0 0.2 0.1 0.3 Ejection V R [m] r**L**u u d Pile-up Pile-up v v v v eject eject A A The combination of mass pileup and ejection explain effective mass ejection. Ejection where pileup factor Ejection For simplicity, Ejection**1**) Reconnection of private flux to common flux 2 ) Reconnection of common flux to private flux j' t j j' j t t t j t j t Mass ejection j j t t AP J Yokoyama Shibata et al. 1996 AP J Yokoyama Shibata et al. 1995**Plasmoid Ejection**(closed flux) formation ejection 40 .43 -.43 .1 0 -.1 Small-size Large-size J [MAm-2] Z[m] Et [Vm-1] 20 20µsec 40µsec 0µsec.09 R[m] .72 60µsec 80µsec Push Merging 0 0 100 200 Time [µsec] Current Sheet Ejection (No closed flux) The high inflow causes ejection of plasmoid with closed flux in the pull merging experiment with high guide field. Pull Merging**Max Et & dV/dt**40 Et [Vm-1] 20 Z [cm] dV/dt [102kms-2] V [kms-1] 0 100 50 Time [µsec] The maximum reconnection speed Et is obtained, when the plasmoid acceleration is maximized. Time evolutions of reconnection electric field Et, position Z, velocity V and acceleration dV/dt of ejecting plasmoid**8**6 4 2 190 195 200 205 Ejection Push Merging Mode Large increase in h occurs 1-2µsec after that in inflow speed.Large increase in inflow speed can not be explained sorely by sheet ejection. [km/sec] High speed rec. at X-point [mm] Delay Uniform Compression 0**How does the sheet ejection cause large increase in?**Thinning of sheet?----NO Ejection Ejection Ejection <ri Ejection Really d <ri? Fractal Sheet? New Effect? The ejection induces the inflow =Br increases Sheet d comp. <ri causes the large increase in h.**Ejection**3 B /B =0.5 B /B =2.2 //0 t t //0 2 B /B =1.0 B /B =2.7 //0 //0 t t m] B /B =1.6 B /B =3.2 t //0 t //0 W 1 Ejection [m (t) 0 0 1 2 3 4 5 6 h X [ / ](t) d r i Large Bt Fine structures of current sheet were observed during the sheet ejection, possibly causing increase in . Each <ri total ri Fractal Sheet? New fine scale probe array in TS-4**CONCLUSIONS**● Huge reconnection heating for fusion plasma startup. ●Large increase in CS resistivity when CS () < i. ●Quasi-steady rec. was transformed to impulsive rec. with comp. force (inflow) in Push Merging exp. • Pileup of density and flux / their ejection. • Pileups of mass increase the rec. speed. 3) The current sheet ejection also causes the high rec. speed due to large mass ejections from X-point region. ●Similar impulsive reconnection in high inflow Pull Merging exp. • Pileup of density &plasmoid ejection cause impulsive rec. in high inflow case. ●Extension of rec. heating to the new UTST exp.**Smal**l ST RF NBI Coils ST Washer-gun plasma ST ST Coils Smal l ST Mer gin g Startu p o f High-Bet a S T usin g Null-Points U. Tokyo UTST Experiment for High-ß ST Startup and RF Sustainment UTST with NBI (0.5MW) PF Coils

More Related