Imposed-dynamo current drive
T.R. Jarboe · B.S. Victor · B.A. Nelson · C.J. Hansen · C. Akcay · D.A. Ennis · N.K. Hicks · A.C. Hossack · G.J. Marklin · R.J. Smith
Summary and citation · read the original at the source · none found
In one page
Thomas Jarboe’s group at the University of Washington runs HIT-SI, a machine that makes a spheromak — a self-organised ring of plasma that holds its own magnetic shape. The hard part of any such machine is keeping a large electric current running inside the plasma with nothing touching it. The old answer was to let the plasma go unstable and let the resulting churn, a dynamo, push the current around; instabilities of that kind also break the magnetic surfaces a fusion reactor needs. Jarboe and his co-authors report a different mechanism. The wiggles that drive the current are not grown by the plasma at all: steady inductive injectors impose them from outside, and shear in the flow of the electron fluid twists those imposed wiggles into current. Their model predicts the measured toroidal current as it evolves, how the injector impedance scales, and the profile the machine produces. That means a stable equilibrium can be sustained efficiently, and the current profile shaped on purpose.
Why it matters hereChapter 12 needs a route to fusion a reactor can actually hold steady, and this is one: current driven by fluctuations you impose rather than by instabilities you have to tolerate. For chapter 9 it is the same physics the site follows in plasmoids — a self-organised magnetic object that can be steered from outside — and the same group carried it straight into a reactor design, the dynomak, at /library/stm-45bcd277ce.
What it claims
01A mechanism for steady inductive helicity injection current drive has been discovered in which the current-driving fluctuations are not generated by the plasma but are imposed by the injectors.Abstract, sentence 1
Published and peer-reviewed02Sheared flow of the electron fluid distorts the imposed fluctuations, and that distortion is what drives the current.Abstract, sentence 2
Published and peer-reviewed03The model accurately predicts the time-dependent toroidal current, the injector impedance scaling, and the profile produced in the HIT-SI experiment.Abstract, sentence 3
Published and peer-reviewed04A stable equilibrium can be efficiently sustained with imposed fluctuations, and the current profile can in principle be controlled — which the authors call two large steps for controlled fusion.Abstract, sentences 4 and 5
Published and peer-reviewed05Some of the effects of the imposed fluctuations on confinement in tokamak and spheromak reactors are assessed, and the degradation may be tolerable.Abstract, sentence 6
What to watch06The mechanism is of interest beyond current drive: to plasma self-organization, to fast reconnection, and to plasma physics in general.Abstract, final sentence
What to watch
The way in
https://doi.org/10.1088/0029-5515/52/8/083017LICENCE CHECK. The version of record is Nuclear Fusion 52 (2012) 083017, published by IOP Publishing; the article record carries IOP’s standard copyright and text-and-data-mining terms and no Creative Commons statement, and the article is marked closed. SOURCE REACHED. The full text was not reachable: the paper predates the US Department of Energy public-access requirement, so the OSTI repository holds only the later HIT-SI papers, and no preprint of it exists on arXiv. This sheet is therefore written from the authors’ own published abstract and the bibliographic record, and every claim locator cites that abstract. The complete paper is at the source.
How to cite it
T.R. Jarboe, B.S. Victor, B.A. Nelson, C.J. Hansen, C. Akcay, D.A. Ennis, N.K. Hicks, A.C. Hossack, G.J. Marklin, R.J. Smith (2012) Imposed-dynamo current drive. doi:10.1088/0029-5515/52/8/083017
Where it sits in the curriculum
Plasmoids, charge clusters and the orbsLattice confinement fusion