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 | 79: Re-optimize the Breakdown process | ||
| Name: | Alan Hyatt ( |
Affiliation: | General Atomics |
| Research Area: | Model based Control | Presentation time: | Not requested | Co-Author(s): | D. Humphreys, M. Walker, J. Leuer, E. Lazarus |
| Description: | Re-optimize the Breakdown process in DIII-D. It has been >10 years since this has been systematically done, and there have been many hardware changes to the tokamak and the power supplies since then. There is ample anecdotal and some systematic evidence that the details of the breakdown significantly affect the plasma trajectory. Reoptimizing the initial breakdown and first 100 msec of rampup should improve reliability and repeatability for all experiments. In addition, sensitivity experiments of gas puff levels, null quality, initial Ip rampup, etc effects on flattop parameters in selected operations scenarios, such as hybrid or AT could be undertaken. | ||
| Experimental Approach/Plan: | Much of the work of reoptimization can be done in 'piggyfront' mode and in the system startup phase before physics operations begins. Sensitivity studies would require dedicated experiments. For these studies systematic variation of gas puff, null quality, etc would undertaken with effects on j(r), li, n(r), p(r), etc measured during rampup and into flattop for a chosen, fixed scenario. | ||
| Background: | The breakdown and first 100 msec of rampup haven't been systematically optimized since 1997. SInce then there have been many changes to the internal hardware of teh device, and many changes to the PF power supplies, including their response to cammands. The effects of these changes have accumulated to the point where breakdown is no longer close to the optimized point help in 1997. A systematic reoptimization of the breakdown and initial rampup process would likely result in better reliability and repeatability of experiments, and could be done in enough detail to begin to quantify the effects of variations in breakdown aspects on the plasma trajectory to flattop. This information could be very useful to thise involved in scenario development, as much of that work involves initial tweaking of the breakdown and rampup. | ||
| Resource Requirements: | Need access to change breakdown aspects if in piggyfront mode. | ||
| Diagnostic Requirements: | MSE is required for physics investigations of breakdown variations' effects on trajectories. | ||
| Analysis Requirements: | No special analysis required. | ||
| Other Requirements: | -- | ||
Print this page