Bragg cell heterodyne interferometry of fast plasma events

Journal Article · Mon Nov 01 04:00:00 EST 1976 · Rev. Sci. Instrum.; (United States)

DOI:https://doi.org/10.1063/1.1134545· OSTI ID:7144217

Kristal, R; Peterson, R W

Plasma interferometry using the fringe shift technique has been extended to the 100-MHz range by the use of Bragg diffraction in a lead molybdate acousto-optic cell. The cell splits a 633-nm laser beam into zero and first-order beams, which are separated in frequency by 80 MHz. These beams are used in the scene and reference arms of a modified Michelson interferometer and are then recombined on a silicon photodetector. Phase changes are deduced from the variations in time separation of consecutive peaks in the beat signal. The technique has been used to make electron density measurements in a 1-m-long, shock heated theta pinch with 6-nsec time resolution. Density variations during the implosion produce a total phase shift of nearly 1 fringe in 150 nsec. Phase noise in vacuum shots (without plasma) is 1/40 fringe rms; the peak-to-peak noise is 1/10 fringe, thus corresponding to a maximum area density (..integral..n dl) uncertainty of 2 x 10/sup 16/ cm/sup -2/. (AIP)

• Research Organization: Los Alamos Scientific Laboratory, Los Alamos, New Mexico 87545
• OSTI ID: 7144217
• Journal Information: Rev. Sci. Instrum.; (United States), Journal Name: Rev. Sci. Instrum.; (United States) Vol. 47:11; ISSN RSINA
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700102* -- Fusion Energy-- Plasma Research-- Diagnostics
BRAGG REFLECTION
ELECTROMAGNETIC RADIATION
ELECTRON DENSITY
FREQUENCY RANGE
INTERFEROMETRY
LASER RADIATION
MHZ RANGE
MHZ RANGE 01-100
PINCH EFFECT
PLASMA DIAGNOSTICS
RADIATIONS
REFLECTION
THETA PINCH