DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 76: Voltage controlled VFI bus operations | ||
| Name: | Alan Hyatt ( |
Affiliation: | General Atomics |
| Research Area: | General PCO | Presentation time: | Not requested | Co-Author(s): | D. Humphreys, M. Walker, J. Leuer |
| Description: | Test the feasibility of using a slow DC supply, like a T or C supply, to actively control the VFI bus voltage. Success will allow us to remove one of the main problems of VFI bus operations - command saturation. | ||
| Experimental Approach/Plan: | Use a C- ot T-supply to actively control the VFI bus voltage in a simple LSN plasma. Requires fairly simple modifications to the patch panel, probably using special cables, and develop the control software for the PCS. Prefer two half days separated by at least one week. | ||
| Background: | The VFI constraint has three different problems: Command saturation (inherent in the VFI), shape control impacted by too many return coils (too few power supplies), and shape control impacted by return coil - neighbor positive feedback (unsophisticated control algorithms). Controlling the VFI bus voltage directly removes the first problem and may affect the third problem positively. Advanced control algorithms would be much easier to generate if the VFI bus voltage was held near zero. Chopper command saturation occurs regularly in DIII-D whenever the VFI bus voltage exceeds 200 V or so. A feasibility test of this concept could be done with existing power supplies and some simple temporary modifications to the patch panel and protection circuitry. | ||
| Resource Requirements: | Simple patch panel mods, probably consisting of special cabling and a protective diode across the supply. A voltage control algorithm for the PCS neeeds to be developed. | ||
| Diagnostic Requirements: | No special measurements required. | ||
| Analysis Requirements: | No special analysis required. | ||
| Other Requirements: | This is a very special patch panel. Reverting to a standard patch will probably take 45-60 min before the next experiment begins. | ||
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