Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The plasma boundary in Single Helical Axis RFP plasmas   Single Helical Axis (SHAx) states obtained in high current reversed field
pinch (RFP) plasmas display, aside from a dominant mode in the m=1 spectrum,
also a dominant m=0 mode, with the same toroidal mode number as the m=1 one.
The two modes have a fixed phase relationship. The island chain created by the
m=0 mode across the reversal surface gives rise, at shallow reversal of the
toroidal field, to an X-point structure which separates the last closed flux
surface from the first wall, creating a divertor-like configuration. The
plasma-wall interaction is found to be related to the connection length of the
field lines intercepting the wall, which displays a pattern modulated by the
dominant mode toroidal periodicity. This configuration, which occurs only for
shallow toroidal field reversal, could be exploited to realize an island
divertor in analogy to stellarators.

17
The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas