Related Experiment Video
Updated: Jun 7, 2026

Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
Far-forward collective scattering measurements of density fluctuations in the helically symmetric experiment
1Department of Physics, University of California, Los Angeles, California 90095, USA.
Abstract:
The multichannel interferometer system on the helically symmetric experiment (HSX) stellarator is reconfigured to perform far-forward collective scattering measurements of electron density fluctuations. The collective scattering system has nine viewing chords with 1.5 cm spacing. Scattered power is measured using a homodyne detection scheme. Far-forward collective scattering provides a line-integrated measurement of fluctuations within the divergence of the probe beam covering wavenumber range: k(⊥)<2 cm(-1). The perpendicular wavenumber consists of poloidal and radial contributions that vary with chord position. Both coherent modes and broadband fluctuation are measured. When HSX is operated without quasihelical symmetry at B(T)=1 T and n(e)∼4×10(12) cm(-3), a coherent electrostatic fluctuation is observed.
Related Concept Videos
Atomic Nuclei: Larmor Precession Frequency
Thomson's e/m Experiment
A particle with charge q, speed v, and mass m enters an area from the top, where the magnetic and electric fields are perpendicular both to the particle's motion and to one another. The magnetic...
Steady, Laminar Flow Between Parallel Plates
Gravitation Between Spherically Symmetric Masses

