Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bounds imposed on the sheath velocity of a dense plasma focus by
  conservation laws and ionization stability condition   Experimental data compiled over five decades of dense plasma focus research
is consistent with the snowplow model of sheath propagation, based on the
hypothetical balance between magnetic pressure driving the plasma into neutral
gas ahead and wind pressure resisting its motion. The resulting sheath
velocity, or the numerically proportional drive parameter, is known to be
approximately constant for devices optimized for neutron production over 8
decades of capacitor bank energy. This paper shows that the validity of the
snowplow hypothesis, with some correction, as well as the non-dependence of
sheath velocity on device parameters, have their roots in local conservation
laws for mass, momentum and energy coupled with the ionization stability
condition. Both upper and lower bounds on sheath velocity are shown to be
related to material constants of the working gas and independent of the device
geometry and capacitor bank impedance.

23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
27
The categories of this paper are: comp-gas
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
16
The categories of this paper are: stat