Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relativistic electron streaming instabilities modulate proton beams
  accelerated in laser-plasma interactions   We report experimental evidence that multi-MeV protons accelerated in
relativistic laser-plasma interactions are modulated by strong filamentary
electromagnetic fields. Modulations are observed when a preplasma is developed
on the rear side of a $\mu$m-scale solid-density hydrogen target. Under such
conditions, electromagnetic fields are amplified by the relativistic electron
Weibel instability and are maximized at the critical density region of the
target. The analysis of the spatial profile of the protons indicates the
generation of $B>$10 MG and $E>$0.1 MV/$\mu$m fields with a $\mu$m-scale
wavelength. These results are in good agreement with three-dimensional
particle-in-cell simulations and analytical estimates, which further confirm
that this process is dominant for different target materials provided that a
preplasma is formed on the rear side with scale length $\gtrsim 0.13 \lambda_0
\sqrt{a_0}$. These findings impose important constraints on the preplasma
levels required for high-quality proton acceleration for multi-purpose
applications.

10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
6
The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg