Summary of Presentations on Plasma Start-up and Progress on Small ST devices from STW2011

R. RamanUniversity of Washington, Seattle, WA

The Joint Meeting of

5th IAEA Technical Meeting on Spherical Tori16th International Workshop on Spherical Torus

(ISTW2011)2011 US-Japan Workshop on ST Plasma

September 27-30, 2011

National Institute for Fusion Science, Toki, Japan

NSTXNSTX Supported by

College W&MColorado Sch MinesColumbia UComp-XGeneral AtomicsINLJohns Hopkins ULANLLLNLLodestarMITNova PhotonicsNew York UOld Dominion UORNLPPPLPSIPrinceton UPurdue USNLThink Tank, Inc.UC DavisUC IrvineUCLAUCSDU ColoradoU MarylandU RochesterU WashingtonU Wisconsin

Culham Sci CtrU St. Andrews

York UChubu UFukui U

Hiroshima UHyogo UKyoto U

Kyushu UKyushu Tokai U

NIFSNiigata UU Tokyo

JAEAHebrew UIoffe Inst

RRC Kurchatov InstTRINITI

KBSIKAIST

POSTECHASIPP

ENEA, FrascatiCEA, Cadarache

IPP, JülichIPP, Garching

ASCR, Czech RepU Quebec 1

This work is supported by US DOE contract numbers FG03-96ER5436, DE-FG02-99ER54519 and DE-AC02-09CH11466

NSTXNSTX Summary of small STs at STW2011

Plasma Start-up, Small STs, Spheromaks

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- NSTX (CHI) PPPL – Raman- PEGASUS (Gun start-up) Univ. of Wisconsin – Fonck- QUEST (RF start-up) Kyushu University – Hanada, Idei, Nishino, Tanaka, Hasegawa,

Yoshida- LATE (RF start-up) Kyoto University – Uchida, Watanabe- UTST & MAST (Merging start-up) Univ. of Tokyo - Yamada- TST-2 (Lower Hybrid) Univ. of Tokyo – Wakatsuki, Ejiri

- HIST (Univ. of Hyogo) – Nagata- SUNIST (Tsinghua Univ.) – Tan, Xie- VEST (Seoul National Univ.) Hwang, Chung- LTX (PPPL) – Majeski- MEDUSA (Univ. of Nuevo León) – Ribeiro

- TOKASTAR-2 (Nagoya Univ.) Hasegawa

- HIT-Si (Steady State Inductive start-up) Univ. of Washington – Victor- TS3, TS4 (Univ. of Tokyo) – Y.Ono

Covered in this Talk, Covered by others/PPPL work

NSTXNSTX Summary of small STs at STW2011

Pegasus (Fonck)

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NSTXNSTX Summary of small STs at STW2011

Experiments Confirm Relaxation Limit Scaling with Toroidal Field and Injector Current

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NSTXNSTX Summary of small STs at STW2011

Gun-Electrode Geometry: PF induction, Plasma size

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NSTXNSTX Summary of small STs at STW2011

Active Gun / Passive Electrode Assembly Points to Simpler, Higher Ip Operation

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NSTXNSTX Summary of small STs at STW2011

Initial Tests of Gun/Electrode Helicity Injection Systems are Promising (up to 170kA achieved)

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NSTXNSTX Summary of small STs at STW2011

Now Developing Larger Surface Area Electrodes

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NSTXNSTX Summary of small STs at STW2011

VEST, Seoul National University (Hwang, Chung)

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Double Null Merging with Partial Solenoids

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Sequential Plasma Injection for Ramp-up

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Innovative Divertor Concepts

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NSTXNSTX Summary of small STs at STW2011

UTST (Univ. of Tokyo) - Yamada

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Double Null Merging (DNM) in UTST with external PF coils- up to 190kA obtained with Central Solenoid induction (~50kA without)

PS coils generate STs at null point

NSTXNSTX Summary of small STs at STW2011

Double Null Merging – only (50 kA)

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Double Null Merging + CS induction (160 kA)

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NSTXNSTX Summary of small STs at STW2011

HIT-SI Spheromak, Brian Victor (U Washington)Ip of 50kA and Record CM of 3 obtained

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Advances in steady inductive helicity injection for plasma start-up and toroidal current drive

NSTXNSTX Summary of small STs at STW2011

Improvement in Toroidal Current is as a result of improved wall conditioning and density control

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HIST – Univ. of Hyogo (Nagata)

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Double Pulsing CHI discharge

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Flux and Current Amplification

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Ribeiro - poster

• The former spherical tokamak MEDUSA (Madison EDUcation Small Aspect ratio tokamak, R < 0.14m, a < 0.10m, BT< 0.5T, Ip < 40kA, 3ms pulse) is currently being transferred to the Autonomous University of Nuevo León (UANL), Mexico

• Goal is student training

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NSTXNSTX Summary of small STs at STW2011

Tokastar-2, Nagoya Univ., Hasegawa

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Preliminary Test with OH induction produced 90A

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