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Fusion Science and Technology
Latest News
DNFSB’s Summers ends board tenure, extending agency’s loss of quorum
Lee
Summers
The Defense Nuclear Facilities Safety Board, the independent agency responsible for ensuring that Department of Energy facilities are protective of public health and safety, announced that the board’s acting chairman, Thomas Summers, has concluded his service with the agency, having completed his second term as a board member on October 18.
Summers’ departure leaves Patricia Lee, who joined the DNFSB after being confirmed by the Senate in July 2024, as the board’s only remaining member and acting chair. Lee’s DNFSB board term ends in October 2027.
A. D. Beklemishev
Fusion Science and Technology | Volume 59 | Number 1 | January 2011 | Pages 90-93
doi.org/10.13182/FST11-A11581
Articles are hosted by Taylor and Francis Online.
Feedback control is routinely used in modern plasma traps for adjusting plasma equilibrium on the transport time scale. Some intrinsic properties of magnetic mirrors make it possible to employ feedback control for stabilization of flute modes as well. Purely electromagnetic plasma-control system that is independent of line-tying or plasma conductivity to the end-plates is proposed. The system adds transverse flexibility to the plasma column, so that any growing perturbation can be deformed to become anti-ballooning. Anti-ballooning form means reduced flute amplitude in bad-curvature regions and enhanced amplitude in expanders or other traditional stabilizers, so that energy of the perturbation becomes positive and the mode is suppressed. Detailed analysis shows that transverse flexibility (or tail-waving) of the discharge can be employed for feedback stabilization even without good-curvature regions. The only requirement is that the discharge inertia (field-weighted plasma density) and the pressure-weighted field curvature are differently distributed along the discharge. If based on inertia, the stabilization mechanism resembles the rope-walker act. Estimates show that the power cost of such stabilization is reasonable and scales inversely with the trap length.