Plasma interferometry and how the bound-electron contribution can bend fringes in unexpected ways

Journal Article · Thu Dec 01 04:00:00 EST 2005 · Applied Optics

DOI:https://doi.org/10.1364/AO.44.0· OSTI ID:20779111

Nilsen, Joseph; Johnson, Walter R

Utilizing a new average atom code, we calculate the index of refraction in C, Al, Ti, and Pd plasmas and show many conditions over which the bound-electron contribution dominates the free electrons as we explore photon energies from the optical to 100 eV (12 nm) soft x rays. For decades measurement of the electron density in plasmas by interferometers has relied on the approximation that the index of refraction in a plasma is due solely to the free electrons and therefore is less than 1. Recent measurements of Al plasmas using x-ray laser interferometers observed fringes bending in the opposite direction than expected due to the bound-electron contribution causing the index of refraction to be larger than 1. During the next decade x-ray free-electron lasers and other sources will be available to probe a wider variety of plasmas at higher densities and shorter wavelengths, so understanding the index of refraction in plasmas is essential.

• OSTI ID: 20779111
• Journal Information: Applied Optics, Journal Name: Applied Optics Journal Issue: 34 Vol. 44; ISSN 0003-6935; ISSN APOPAI
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
APPROXIMATIONS
ELECTRON DENSITY
ELECTRONS
EV RANGE 10-100
FREE ELECTRON LASERS
INTERFEROMETERS
INTERFEROMETRY
PLASMA
REFRACTIVE INDEX
SOFT X RADIATION
ULTRAVIOLET SPECTRA
X-RAY LASERS