Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Positron Acceleration in an Elongated Bubble Regime   A new concept is proposed for accelerating positrons in a nonlinear plasma
wakefield accelerator. By loading the wakefield (back of the plasma bubble)
with a short electron bunch, an extended area of excessive plasma electron
accumulation is created after the first bubble, resulting in a favorable region
with simultaneous focusing and accelerating fields for positrons. Scaling laws
for optimized loading parameters are obtained through extensive parameters
scans. Owing to the good quality of the focusing field, positron acceleration
with emittance preservation can be achieved in this new regime and it has been
demonstrated in the three-dimensional particle-in-cell simulations.

17
The categories of this paper are: q-fin
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th