Laser-initiated channels for ion transport: breakdown and channel evolution
The electrical breakdown and discharge evolution in CO/sub 2/ laser-heated molecular gases has been studied. With the laser tuned to a vibrational mode of NH/sub 3/, C/sub 2/H/sub 4/, CH/sub 2/CHCN, or CH/sub 3/OH the breakdown potential decreases as much as 10-fold for laser pulse energies up to 35 J/cm/sup 2/. The subsequent 50--142-cm discharges are straight, stable, and reproducible. Analogous tests in D/sub 2/ and air yield only a small alteration of breakdown potential and do not cause a straight discharge. The expansion of the initial laser-heated gas has been modeled by the CHARTB hydrocode with the addition of the NH/sub 3/ equation of state in tabular and analytic form to that code. The breakdown characteristics and initial expansion stage confirm the earlier calculation of laser heating to 1900--2100 /sup 0/K. Experimental observations of the discharge evolution in NH/sub 3/ have measured (1) the radial expansion velocity by streak-camera photography of the H/sub ..beta../ emission zone, (2) the plasma temperature by the Niv/Niii line-ratio method, and (3) the electron-density profile by holographic interferometry. The central zone of the channel is heated to 5.5 eV and expands with a radial velocity of 1.0--1.2 mm/..mu..s for the case of a 27-kA discharge in 20 Torr of NH/sub 3/. Preliminary hydrocode simulations of the discharge show qualitative agreement with observations.
- Research Organization:
- Sandia National Laboratories, Albuquerque, NM 87185
- DOE Contract Number:
- DE-AC04-76-DP00789
- OSTI ID:
- 6188084
- Journal Information:
- J. Appl. Phys.; (United States), Vol. 52:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AMMONIA
ELECTRIC DISCHARGES
ION CHANNELING
BREAKDOWN
CARBON DIOXIDE LASERS
DEUTERIUM
ELECTRON DENSITY
EQUATIONS OF STATE
HEATING
HYDROCARBONS
INTERFEROMETRY
LASER RADIATION
ORGANIC COMPOUNDS
PULSES
RADIATION EFFECTS
SPATIAL DISTRIBUTION
STREAK PHOTOGRAPHY
VIBRATIONAL STATES
CHANNELING
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
EQUATIONS
EXCITED STATES
GAS LASERS
HYDRIDES
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
ISOTOPES
LASERS
LIGHT NUCLEI
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
NUCLEI
ODD-ODD NUCLEI
PHOTOGRAPHY
RADIATIONS
STABLE ISOTOPES
700100* - Fusion Energy- Plasma Research