Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The effect of Joule heating on the terahertz radiation in the
  superconductor media   Moving vortex lattice in type-II superconductors can result in the radiation
of electromagnetic waves in the range of terahertz frequency. The vortex flow
dynamics in superconductors follow the London equation. In this paper, the
effects of the superconductor coherence length and the London penetration depth
on the radiated power is investigated by solving the London equation in the
presence of vortices. The results show that by decreasing the coherence length,
the radiation power will significantly increase. Also, it is possible to obtain
more radiated power with a sharp peak by increasing the penetration depth.
Further investigation of the effect of Joule heating reveals that radiation
power is almost independent of temperature when we are far from critical
temperature. But on the other hand, near the critical temperature, the
radiation power is strongly dependent on the temperature variation. Also, by
increasing the bias current, the radiation power will augment, and the
frequency of radiated peaks will change accordingly.

28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
15
The categories of this paper are: nucl-ex