Status On Multi-microsecond Prepulse Technique On Sphinx Machine Going From Nested To Single Wire Array For 800 ns Implosion Time Z-pinch

Journal Article · Wed Jan 21 04:00:00 EST 2009 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3079763· OSTI ID:21255372

Maury, P; Calamy, H; Grunenwald, J; Lassalle, F; Zucchini, F; Loyen, A; Georges, A; Morell, A; Bedoch, J P ^[1]

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1. Centre d'Etudes de Gramat, BP 80200 46500 Gramat (France)

The Sphinx machine{sup [1]} is a 6 MA, 1 {mu}S driver based on the LTD technology, used for Z-pinch experiments. Important improvements of Sphinx radiation output were recently obtained using a multi-microsecond current prepulse{sup [2]}. Total power per unit of length is multiplied by a factor of 6 and FWHM divided by a factor of 2.5. Early breakdown of the wires during the prepulse phase dramatically changes the ablation phase leading to an improvement of axial homogeneity of both the implosion and the final radiating column. As a consequence, the cathode bubble observed on classical shots is definitively removed. The implosion is then centered and zippering effect is reduced, leading to simultaneous x-ray emission of the whole length. A great reproducibility is obtained. Nested arrays were used before to mitigate the Rayleigh-Taylor instabilities during the implosion phase. Further experiments with pre-pulse technique are described here were inner array was removed. The goal of these experiments was to see if long prepulse could give stable enough implosion with single array and at the same time increase the {eta} parameter by reducing the mass of the load. Experimental results of single wire array loads of typical dimension 5 cm in height with implosion time between 700 and 900 ns and diameter varying between 80 and 140 mm are given. Parameters of the loads were varying in term of radius and number of wires. Comparisons with nested wire array loads are done and trends are proposed. Characteristics of both the implosion and the final radiating column are shown. 2D MHD numerical simulations of single wire array become easier as there is no interaction between outer and inner array anymore. A systematic study was done using injection mass model to benchmark simulation with experiments.

• OSTI ID: 21255372
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 1088; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ABLATION
BENCHMARKS
CATHODES
IMPLOSIONS
LINEAR Z PINCH DEVICES
MAGNETOHYDRODYNAMICS
MASS
PLASMA PRODUCTION
PULSE TECHNIQUES
RAYLEIGH-TAYLOR INSTABILITY
SIMULATION
WIRES
X RADIATION