1. Summary of Presentations on Plasma Start-up and Progress on Small ST devices from STW2011 R. Raman University of Washington, Seattle, WA The Joint Meeting of 5th IAEA Technical Meeting on Spherical Tori 16th International Workshop on Spherical Torus (ISTW2011) 2011 US-Japan Workshop on ST Plasma September 27-30, 2011 National Institute for Fusion Science, Toki, Japan NSTX Supported by College W&M Colorado Sch Mines Columbia U Comp-X General Atomics INL Johns Hopkins U LANL LLNL Lodestar MIT Nova Photonics New York U Old Dominion U ORNL PPPL PSI Princeton U Purdue U SNL Think Tank, Inc. UC Davis UC Irvine UCLA UCSD U Colorado U Maryland U Rochester U Washington U Wisconsin Culham Sci Ctr U St. Andrews York U Chubu U Fukui U Hiroshima U Hyogo U Kyoto U Kyushu U Kyushu Tokai U NIFS Niigata U U Tokyo JAEA Hebrew U Ioffe Inst RRC Kurchatov Inst TRINITI KBSI KAIST POSTECH ASIPP ENEA, Frascati CEA, Cadarache IPP, Jülich IPP, Garching ASCR, Czech Rep U Quebec 1 This work is supported by US DOE contract numbers FG03- 96ER5436, DE-FG02-99ER54519 and DE-AC02-09CH11466

2. NSTX Summary of small STs at STW2011 Plasma Start-up, Small STs, Spheromaks 2 - 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

3. NSTX Summary of small STs at STW2011 Pegasus (Fonck) 3

4. NSTX Summary of small STs at STW2011 Experiments Confirm Relaxation Limit Scaling with Toroidal Field and Injector Current 4

5. NSTX Summary of small STs at STW2011 Gun-Electrode Geometry: PF induction, Plasma size 5

6. NSTX Summary of small STs at STW2011 Active Gun / Passive Electrode Assembly Points to Simpler, Higher Ip Operation 6

7. NSTX Summary of small STs at STW2011 Initial Tests of Gun/Electrode Helicity Injection Systems are Promising (up to 170kA achieved) 7

8. NSTX Summary of small STs at STW2011 Now Developing Larger Surface Area Electrodes 8

9. NSTX Summary of small STs at STW2011 VEST, Seoul National University (Hwang, Chung) 9

10. NSTX Summary of small STs at STW2011 Double Null Merging with Partial Solenoids 10

11. NSTX Summary of small STs at STW2011 Sequential Plasma Injection for Ramp-up 11

12. NSTX Summary of small STs at STW2011 Innovative Divertor Concepts 12

13. NSTX Summary of small STs at STW2011 UTST (Univ. of Tokyo) - Yamada 13 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

14. NSTX Summary of small STs at STW2011 Double Null Merging – only (50 kA) 14

15. NSTX Summary of small STs at STW2011 Double Null Merging + CS induction (160 kA) 15

16. NSTX Summary of small STs at STW2011 HIT-SI Spheromak, Brian Victor (U Washington) Ip of 50kA and Record CM of 3 obtained 16 Advances in steady inductive helicity injection for plasma start- up and toroidal current drive

17. NSTX Summary of small STs at STW2011 Improvement in Toroidal Current is as a result of improved wall conditioning and density control 17

18. NSTX Summary of small STs at STW2011 HIST – Univ. of Hyogo (Nagata) 18

19. NSTX Summary of small STs at STW2011 Double Pulsing CHI discharge 19

20. NSTX Summary of small STs at STW2011 Flux and Current Amplification 20

21. NSTX Summary of small STs at STW2011 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 21

22. NSTX Summary of small STs at STW2011 Tokastar-2, Nagoya Univ., Hasegawa 22

23. NSTX Summary of small STs at STW2011 Preliminary Test with OH induction produced 90A 23