DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2013 EXPERIMENTAL CAMPAIGN
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| Title | 329: Discussion of plasma rotation transient process during OFM/ELM-driven RWM w/wo feedback usin | ||
| Name: | Michio Okabayashi mokabaya@pppl.gov | Affiliation: | Princeton Plasma Physics Laboratory |
| Research Area: | Stability & Disruption Avoidance | Presentation time: | Not requested |
| Co-Author(s): | Yueqinag Liu | ITPA Joint Experiment : | No |
| Description: | Current hypothesis of RWM stabilization in high beta plasmas is that sufficient energetic particles (EP) and high plasma rotation can increase the stabilizing effect over the external kink driving source.
However, the major contributor EPs potentially can cause deleterious effect by inducing various types of MHD activities. In particular, onset of EP-driven off-axis fishbone modes (OFM) causes rapid decrease of EP population. This results in decrease of another stabilizing effect of plasma rotation within a short time period before these properties can be restored by adjusting auxiliary heating system [1]. Here, the rotation drop is partly due to non-ambipolar Er buildup with rapid EP losses. In addition, the increase of mode amplitude reduces the rotation due to increase of dissipative Electro magnetic(EM) torque. Thus, the discussion based on the steady state criterion only may become irrelevant once plasma reaches near the ideal MHD stability limit. In addition, when the feedback is used, the applied feedback field can induce non-resonant effect modifying rotation profile due to NTV. Recently, a time dependent MARS-Q code has been developed [2] to include the time evolution of mode amplitude and rotational profile. Various viscous effects, such as Electro magnetic(EM) torque and NTV are included in this code. Plasma condition Recently, the SSI group has developed betan AT plasmas ( 1.5 < q_min < 2) bn~4 near MHD limit. In these discharges, we observed EP-driven RWMs and ELMs, and slow n=1 magnetic burst without any D-alpha spike. These discharges are well suited for studying RWM stability. The initial objective of this experiment is to document the rotation and Ti profile evolution with fast time scaling to assess the adequacy of MARS-Q applicability. Then, we use the ode as a simulator to improve the plasma performance. Ref (1) M. Okabayashi et al, Phys. Plasmas 18, 056112 (2011); (2) Y.Q. Liu et al., Plasma Phys. Control. Fusion, 2012, 54124013 (3) M. G. Matsunaga et al., IAEA 2012 EX5-1 |
ITER IO Urgent Research Task : | No |
| Experimental Approach/Plan: | -- | ||
| Background: | -- | ||
| Resource Requirements: | -- | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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