Computational investigation of single mode vs multimode Rayleigh{endash}Taylor seeding in Z-pinch implosions

Journal Article · Tue Dec 01 04:00:00 EST 1998 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.873153· OSTI ID:664688

Douglas, M R; Deeney, C ^[1]; Roderick, N F ^[2]

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1. Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)
2. University of New Mexico, Albuquerque, New Mexico 87102 (United States)

A series of two-dimensional magnetohydrodynamic calculations have been carried out to investigate single and multimode growth and mode coupling for magnetically-driven Rayleigh{endash}Taylor instabilities in Z pinches. Wavelengths ranging from 5.0 mm down to 1.25 mm were considered. Such wavelengths are comparable to those observed at stagnation using a random density {open_quotes}seeding{close_quotes} method. The calculations show that wavelengths resolved by less than 10 cells exhibit an artificial decrease in initial Fourier spectrum amplitudes and a reduction in the corresponding amplitude growth. Single mode evolution exhibits linear exponential growth and the development of higher harmonics as the mode transitions into the nonlinear phase. The mode growth continues to exponentiate but at a slower rate than determined by linear hydrodynamic theory. In the two and three mode case, there is clear evidence of mode coupling and inverse cascade. In addition, distinct modal patterns are observed late in the implosion, resulting from finite shell thickness and magnetic field effects. {copyright} {ital 1998 American Institute of Physics.} thinsp

• OSTI ID: 664688
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 12 Vol. 5; ISSN 1070-664X; ISSN PHPAEN
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
IMPLOSIONS
LINEAR Z PINCH DEVICES
MAGNETOHYDRODYNAMICS
PINCH EFFECT
PLASMA INSTABILITY
RAYLEIGH-TAYLOR INSTABILITY