Hybrid Stellarator Divertor
Abstract
Recently an efficient method for simulation of stellarator divertor was developed by Boozer and Punjabi. This method was used to simulate nonresonant stellarator divertor. The three parameters denoted by ɛ0, ɛt, and ɛx in the Hamiltonian for the trajectories of magnetic field lines control the shape of the outermost confining surface in nonresonant stellarator divertor. These parameters are called shape parameters. They control the elongation, triangularity, and the sharp edges on the outermost confining surface, respectively. In the 2020 Punjabi and Boozer paper on simulation of nonresonant stellarator divertor in PoP, the shape parameters had the values ɛ0 =ɛt = 0.5, and ɛx = -0.31. It is found that in for ɛ0 =ɛt = 0.5, when ɛx is varied in the range -0.25 to -0.1, a new kind of divertor is formed. We call this hybrid divertor. Hybrid divertor has features of both the nonresonant divertor as well as the resonant divertor. The size of the resonant islands varies as ɛx is varied in this range; islands become smaller as ɛx --> -1/4. In this paper, we give the rotational transforms and sizes of the islands for different values of the parameter ɛx in this range.
Work supported by the DOE OFES Grants DE-SC0020107 and DE-FG02-07ER54937 to Hampton University, and DE-FG02-03ER54696 to Columbia University. Research used resources of the NERSC, supported by the Office of Science, U.S. DOE, under Contract No. DE-AC02-05CH11231.- Publication:
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APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- 2020
- Bibcode:
- 2020APS..DPPJ13083L