1 / 19

磁力管合体における磁気ヘリシティー保存性に関する実験的検証 小野靖 , 河森栄一郎 TS-3 & 4 グループ 東京大学・高温プラズマ研究センター

磁力管合体における磁気ヘリシティー保存性に関する実験的検証 小野靖 , 河森栄一郎 TS-3 & 4 グループ 東京大学・高温プラズマ研究センター. 3. m]. B /B =0.5. B /B =2.2. //0. z. z. //0. W. 2. B /B =1.0. B /B =2.7. //0. //0. z. z. [m. B /B =1.6. B /B =3.2. z. //0. z. //0. (t). 1. z. h. 0. 0. 1. 2. 3. 4. 5.

rowa
Download Presentation

磁力管合体における磁気ヘリシティー保存性に関する実験的検証 小野靖 , 河森栄一郎 TS-3 & 4 グループ 東京大学・高温プラズマ研究センター

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

Presentation Transcript

  1. 磁力管合体における磁気ヘリシティー保存性に関する実験的検証磁力管合体における磁気ヘリシティー保存性に関する実験的検証 小野靖, 河森栄一郎 TS-3 & 4 グループ 東京大学・高温プラズマ研究センター

  2. 3 m] B /B =0.5 B /B =2.2 //0 z z //0 W 2 B /B =1.0 B /B =2.7 //0 //0 z z [m B /B =1.6 B /B =3.2 z //0 z //0 (t) 1 z h 0 0 1 2 3 4 5 6 [ / ](t) r d i Progress in TS-3/4 Merging ST Exp. Ion particle effect on rec. speed 2. Anomalos ion heating High-ß ST ramp-up 3. Plasmoid ejection

  3. Loop top hard X-ray sources Masuda et al. 1994 Shibata et al. 1995 Clear evidence of ion heating by outflow!

  4. CONTENTS Helicity effect of two colliding force-free toroids Helicity control by co / counter-helicity merging. 1) Global Helicity Effect ----Global bifurcated relaxations (Nucl. Fusion ‘99) ● Taylor relxation to low-ß force-free state. ● New kinetic relaxations to high-ß state ●Helicity conservation / annihilation /energy release Yokoyama, Shibata Nature ‘95 Shimizu, Tsuneta, Astrophys. J. 93

  5. What will the merging spheromaks with varied K relax to ?The counterheilcity merging varied K from zero to KTaylor. Total helicity K=0 Large K K=KTaylor

  6. K／W Scan Experiment ヘリシティーのバランスしない２個のスフェロマックの合体を用いると（ＭＨＤ 不安定の問題なく）プラズマ全体の磁気ヘリシティーＫ／磁気エネルギーＷを （０付近でも）自由に設定できる。 スフェロマック＃１（Taylor 状態） K1／W1= a スフェロマック＃２（Taylor 状態） K2／W2= a 合体プラズマの磁気ヘリシティー K = K1 - K2 （Counter-helicity Merging のため) 合体プラズマの磁気エネルギー W = W1 + W2 （ Merging のタイプに無関係） ２個の初期スフェロマックの磁気ヘリシティー比 K2/ K1 （磁束比F2/ F1=a）を０から１まで変化させれば、 K/W値は ０からTaylor 状態の値 = aの範囲で自由に設定することができる。

  7. Global Effect: How do the merging toroids relax?Force-Free Loop (Spheromak) vs. High-ß Loop (FRC) Spheromak Taylor State low-ß state FRC High-ß state

  8. Bifurcated Relaxations to Non-Tayor State (FRC)and to Taylor State: Spheromak Merging spheromaks with Kc>K>0relax to a Non-Taylor state: high-ß FRC.

  9. Bifurcated Relaxations to Non-Tayor State (FRC)and to Taylor State: Spheromak b) Merging spheromaks with KTaylor>K>Kc relax to a Taylor state: spheromak

  10. Taylor Relaxation to another spheromak Non-Taylor Relaxation (Annihilation of helicity) KTaylor>K>Kc ⇨ K/W approaches (K/W)Taylor------ Tayor RelaxationKc>K>0 ⇨ K/W approaches 0 ------ Non-Tayor Relaxation Taylor State (spheromak)

  11. Large Increase in Ti ⇨ Relax to High-ß FRC No Increase in Ti ⇨ Relax to Taylor State Spheromak Relaxation to an FRC Relaxation to another spheromak

  12. Energy Loss Flux conversion toroidal magnetic energy Spheromak (ß=0-0.1) The largest magnetic energy release of counterhelicity reconnection. If toroidally symmetric and kinetic (fusion plasma), relaxation to an FRC. If not (solar coronas etc.), the most violent energy release to space. See Y. Ono et al. Phys. Rev. Lett. 76, 3328, ‘99.

  13. If rBt>>ri, Taylor relxation loses huge energybecauseK:conserved, W: relax to lK. Magnetic energy of produced spheromak Wloss huge energy loss Relaxation to Spheromak? Knorm How does the merging causes large energy-release?If merging toroids have Knorm>0.4, relaxation to min. energy state causes energy loss W(const.)-lK. However, if Knorm<0.2, they relax to another stable state. W=const., K is varied.

  14. Relaxation to FRC (high-ß) Relaxation to spheromak (force-free) Possible Mechanism for the Bifurcated Relaxations:Poloidal current Ip was maintained or annihilateddepending on Ip loop radius rBt>ri or rBt<ri . Knorm=(K/W) /(K/W) Taylor

  15. Mechanisms for Taylor and new high-ß relaxations Low-ß relaxation High-ß relaxation

  16. Taylor relaxation Taylor relaxation FRC relaxation Small i TS-4 large ri(~i ) exp.:RTS-4≈3RTS-3The regime for FRC relaxation is wider in Ar discharge with larger i,while that for the Taylor relxation is wider in H discharge with smaller i. K/KTaylor Large i Time evolutions of normalized eigenvalues K/KTaylor of merging spheromaks with varied initial helicities (K/KTaylor =1: Taylor state) K/KTaylor

  17. テーラー状態へ緩和する限界となる境界値l/ lはS*が大きいほど広範囲.回転が止まる範囲とTaylor 緩和する範囲が一致l：緩和前の固有値(j/B)ly：緩和前の固有値(l=jp/Bp)S*：プラズマ径/イオンスキン長 Taylor状態へ緩和 K/KTaylor FRCへ 緩和

  18. CONCLUSIONS Helicity Effects on Reconnection/Mergingwere studied using co/ counterhelicity mergingwith varied K but equal W Global Effect ------- Bifurcated relaxations 1) Two merging force-free plasmas relax either to another force-free plasmas or to high-ß FRC, depending on whether initial K>Kc or K<Kc . 2) The threshold value Kc is dermined by that where ri=rBt, indicating the high-ß relaxation is caused by some kinetic effect. 3) The largest energy release was observed in counterhelicity reconnection with ri <<rBt.

  19. TS-4 ST/ FRC Merging Device Operation: 1) FRC merging formation 2) High-ß ST formation by FRC 3) Boundary study of CTs/STs R=0.4-0.55m, A=1.2-1.9, Bt0<3-5kG, Ip≈300kA

More Related