Large-scale-length nonuniformities in gas puff implosions
Because they are less susceptible to the hydromagnetic Rayleigh--Taylor instability than other fast Z-pinch imploding liner systems, gas puffs offer the possibility of higher implosion velocity. This higher specific energy appears necessary for optimizing high-energy x rays required in a photoionization-pumped soft x-ray laser. Nevertheless, large-scale-length nonuniformities created as the gas flows from the nozzle across the electrode gap are a potential problem. One- and two-dimensional calculations suggest that gas near the nozzle will implode before that which is further from the nozzle, leading to an effect described as ''zippering.'' Because the number of such two-dimensional calculations that can be done is limited and because the density distribution of nozzles is uncertain, we have developed a simple quasi-two-dimensional interface code that is able to quickly survey the effect of arbitrary initial gas distributions on the implosion dynamics. Results of this survey suggest that zippering contributes significantly to thermalization time, and we propose two methods to counteract this problem. These techniques, each of which involves tailoring the initial density distribution to offset effects of nonuniformities, appear promising. Nevertheless, we will never completely eliminate these nonuniformities, therefore, they must be accounted for in x-ray laser target design.
- Research Organization:
- Sandia National Laboratories, Albuquerque, New Mexico 87185
- OSTI ID:
- 6100747
- Journal Information:
- J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 59:8; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
420300 -- Engineering-- Lasers-- (-1989)
640430* -- Fluid Physics-- Magnetohydrodynamics
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
FLUID FLOW
FLUID MECHANICS
GAS FLOW
HYDRODYNAMICS
IMPLOSIONS
IONIZATION
LASER TARGETS
LASERS
LINEAR PINCH DEVICES
LINEAR Z PINCH DEVICES
MAGNETOHYDRODYNAMICS
MECHANICS
NOZZLES
OPEN PLASMA DEVICES
PHOTOIONIZATION
PINCH DEVICES
PINCH EFFECT
PUMPING
TARGETS
THERMONUCLEAR DEVICES
TWO-DIMENSIONAL CALCULATIONS
X-RAY LASERS