Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 3D Theory of the Plasma Cascade Instability   The plasma cascade instability (PCI) is a proposed mechanism for
microbunching in electron beams without dipole magnets. Existing theory is
limited to wave propagation that is orthogonal to the advective compression
direction. This work provides a theory allowing for wave propagation in
arbitrary directions.

26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph