Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Parametric instability of the helical dynamo   We study the dynamo threshold of a helical flow made of a mean (stationary)
plus a fluctuating part. Two flow geometries are studied, either (i) solid body
or (ii) smooth. Two well-known resonant dynamo conditions, elaborated for
stationary helical flows in the limit of large magnetic Reynolds numbers, are
tested against lower magnetic Reynolds numbers and for fluctuating flows (zero
mean). For a flow made of a mean plus a fluctuating part the dynamo threshold
depends on the frequency and the strength of the fluctuation. The resonant
dynamo conditions applied on the fluctuating (resp. mean) part seems to be a
good diagnostic to predict the existence of a dynamo threshold when the
fluctuation level is high (resp. low).

0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an