DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
Login | Review | Submit | Logout | Help
Questions about this website? Contact Andrew LeBlanc Questions about ROF? Contact Chuck Greenfield
| Title | 30: High beta error field threshold | ||
| Name: | Holger Reimerdes ( |
Affiliation: | Columbia University |
| Research Area: | Rotation Physics | Presentation time: | Not requested | Co-Author(s): | -- |
| Description: | The goal of this experiment is to develop an estimate of the high beta n=1 error field threshold and corresponding torque requirement and use it for an empirically or model-based extrapolation to ITER. The n=1 error field threshold is measured as a function of input torque and helicity (resonant component). | ||
| Experimental Approach/Plan: | The error field threshold is measured in quasi-stationary n=1 error field ramps in plasmas, where beta exceeds the no-wall stability limit. In addition to the error field threshold, we plan to measure the plasma response at the threshold. The measurement of the perturbed poloidal and radial magnetic field (and its toroidal phase) at the wall directly yields an independent estimate of the electro-magnetic torque, which can then be compared to transport calculations based on beam torque models and empirical momentum diffusion. The measurements are repeated at several values of input torque and with various poloidal spectra using C- and I-coils. | ||
| Background: | Experiments with balanced beams have shown that the rotation required for operation above the no-wall stability limit in the presence of error fields is significantly higher than in an axisymmetric configuration. This increase of the rotation threshold with applied n=1 fields implies a limit on tolerable error fields, which supposedly can be traded off against an increased momentum input. The effect of resonant field amplification at values of beta above the ideal MHD no-wall stability limit significantly reduces the error field tolerance with respect to low-beta error field thresholds. | ||
| Resource Requirements: | 5 co + 2 counter NBI beams | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
Print this page