10,894 research outputs found
The slow-mode nature of compressible wave power in solar wind turbulence
We use a large, statistical set of measurements from the Wind spacecraft at 1
AU, and supporting synthetic spacecraft data based on kinetic plasma theory, to
show that the compressible component of inertial range solar wind turbulence is
primarily in the kinetic slow mode. The zero-lag cross correlation C(delta n,
delta B_parallel) between proton density fluctuations delta n and the
field-aligned (compressible) component of the magnetic field delta B_parallel
is negative and close to -1. The typical dependence of C(delta n,delta
B_parallel) on the ion plasma beta_i is consistent with a spectrum of
compressible wave energy that is almost entirely in the kinetic slow mode. This
has important implications for both the nature of the density fluctuation
spectrum and for the cascade of kinetic turbulence to short wavelengths,
favoring evolution to the kinetic Alfven wave mode rather than the (fast)
whistler mode.Comment: 4 pages, 5 figures, submitted to Phys Rev Letter
Nacht Auf Dem Rheine : Night on the Rhine
https://digitalcommons.library.umaine.edu/mmb-ps/1844/thumbnail.jp
Mid-IR frequency measurement using an optical frequency comb and a long-distance remote frequency reference
We have built a frequency chain which enables to measure the absolute
frequency of a laser emitting in the 28-31 THz frequency range and stabilized
onto a molecular absorption line. The set-up uses an optical frequency comb and
an ultrastable 1.55 m frequency reference signal, transferred from
LNE-SYRTE to LPL through an optical link. We are now progressing towards the
stabilization of the mid-IR laser via the frequency comb and the extension of
this technique to quantum cascade lasers. Such a development is very
challenging for ultrahigh resolution molecular spectroscopy and fundamental
tests of physics with molecules
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