Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nanoscale Nonlinear Radio Frequency Properties of Bulk Nb : Origins of
  Extrinsic Nonlinear Effects   The performance of Niobium-based Superconducting Radio Frequency (SRF)
particle accelerator cavities can be sensitive to localized defects that give
rise to quenches at high accelerating gradients. In order to identify these
material defects on bulk Nb surfaces at their operating frequency and
temperature, a wide bandwidth microwave microscope with localized and strong RF
magnetic fields is developed by integrating a magnetic write head into the
near-field microwave microscope to enable mapping of the local electrodynamic
response in the multi-GHz frequency regime at cryogenic temperatures. This
magnetic writer demonstrates a localized and strong RF magnetic field on bulk
Nb surface with $B_{surface}$ > 102 mT and sub-micron resolution. By measuring
the nonlinear response of the superconductor, nonlinearity coming from the
nano-scale weak link Josephson junctions due to the contaminated surface in the
cavity fabrication process is demonstrated.

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The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
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The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
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The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
5
The categories of this paper are: gr-qc