Measurement of the development and evolution of shock waves in a laser- induced gas breakdown plasma

Journal Article · Sat Nov 01 04:00:00 EST 1975 · Phys. Fluids, v. 18, no. 11, pp. 1460-1466

DOI:https://doi.org/10.1063/1.861045· OSTI ID:4106194

Chu, T K; Johnson, L C

Space- and time-resolved interferometric measurements of electron density in CO$sub 2$-laser produced plasmas in helium or hydrogen are made near the laser focal spot. Immediately after breakdown, a rapidly growing region of approximately uniform plasma density appears at the focal spot. After a few tens of nanoseconds, shock waves are formed, propagating both transverse and parallel to the incident laser beam direction. Behind the transverse propagating shock is an on-axis density minimum, which results in laser-beam self-trapping. The shock wave propagating toward the focusing lens effectively shields the interior plasma from the incident beam because the lower plasma temperature and higher plasma density in the shock allow strong absorption of the incident beam energy. By arranging the laser radiation-plasma interaction to begin at a plasma-vacuum interface at the exit of a free-expansion jet, this backward propagating shock wave is eliminated, thus permitting efficient energy deposition in the plasma interior. (AIP)

• Research Organization: Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08540
• Sponsoring Organization: USDOE
• NSA Number: NSA-33-014566
• OSTI ID: 4106194
• Journal Information: Phys. Fluids, v. 18, no. 11, pp. 1460-1466, Journal Name: Phys. Fluids, v. 18, no. 11, pp. 1460-1466; ISSN PFLDA
• Country of Publication: United States
• Language: English

Related Subjects

*LASER-PRODUCED PLASMA-- PLASMA DIAGNOSTICS
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ELECTRON DENSITY
INTERFEROMETRY
N70800* --Physics--Controlled Thermonuclear Research-- Thermonuclear Engineering & Equipment
SHOCK WAVES
TRAPPING