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GA – A 24851 CONTROL OF THE RESISTIVE WALL MODE WITH INTERNAL COILS IN THE DIII-D TOKAMAK by
| Content Provider | Semantic Scholar |
|---|---|
| Author | Okabayashi, Masahiro Bialek, Jakub Bondeson, Anders Chance, Michael S. Edgell, Dana Harold Garofalo, Andrea M. Hatcher, Ryan Jackson, Grayson L. Jayakumar, Raghavan Jensen, T. H. Katsuro-Hopkins, Oksana Haye, Robert J. La Liu, Yueqiang Navratil, Gerald Anton Reimerdes, Holger Scoville, John T. Takahashi, Hidenori Takechi, Manabu Turnbull, Alan D. Bogatu, Ioan N. Gohil, Punit Kim, Jong Soo Makowski, Michael A. Manickam, J. |
| Copyright Year | 2005 |
| Abstract | New coils were installed inside the vacuum vessel of the DIII-D device for producing nonaxisymmetric magnetic fields. These “ Internal-Coils” are predicted to stabilize the Resistive Wall Mode (RWM) branch of the long-wavelength external kink mode with plasma beta close to the ideal wall limit. Feedback using these new Internal-Coils was found to be more effective when compared with using the External-Coils located outside the vacuum vessel, because the location inside the vessel allows faster response and their geometry also couples better to the helical mode structure. A proper choice of feedback gain increased the plasma beta above the no-wall limit to C 0.9, where C is a measure of achievable beta above no-wall limit defined as ( no-wall.limit)/( ideal.wall.limit– no.wall.limit). The feedback system with Internal-Coils can suppress the RWM up to the normalized growth rate w ~ 10 ( w is the resistive flux penetration time of the wall). The feedback-driven dynamic error field correction helps to stabilize the RWM by reducing the rotational drag for rot > crit, where rot is the angular rotation frequency of plasma and crit is the critical value for the rotational stabilization. When rot ~ crit/2, the feedback system must stabilize the RWM mainly through direct magnetic control of the mode. The estimated crit/ A is 2.5% by the MARS-F code analysis with experimentally observed profiles, where A is the Alfvén angular rotational frequency at q = 2 surface. The MARS-F code also predicts that for successful RWM magnetic feedback control the power supply characteristic time should be a fraction of the growth time of the targeted RWM. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://fusion.gat.com/pubs-ext/IAEA04/A24851.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
