Electromagnetic Implosion of Spherical Liner

Abstract

We have magnetically driven a tapered-thickness spherical aluminum shell implosion with a 12.5 MA axial discharge. The initially 4 cm radius, O. l to 0.2 cm thick,~45 latitude shell was imploded along conical electrodes. The implosion time was approximately 15 p, sec. Radiography indicated substantial agreement with 2D-MHD calculations. Such calculations for this experiment predict final inner-surface implosion velocity of 2.5 to 3 cm/p, sec, peak pressure of 56 Mbar, and peak density of 16.8 g/cm-'

The physics of fast Z pinches

“…This kind of Z pinch also falls under the aforementioned definition of "fast" Z pinches and will be covered by our survey. As an example, one can mention spherical implosions of metal shells (Baker et al, 1978;Degnan et al, 1995). A schematic of the latter experiment, where quasi-spherical implosions were successfully realized, is shown in Fig.…”

“…The m a y had 240 wires; the mass per unit length of the array was 2 mg/cm; d) A high-Z liner imploding on a low-density foam (Matzen, 1997). An internal ICF capsule is situated in the center of the foam cylinder; e) A quasi-spherical liner implosion (Degnan et al, 1995). An aluminum liner slides along conical electrodes.…”

“…I.le with the implosion time of the order of 1 ps, slower generators are required. Examples of such generators are Shiva Star situated at the Phillips Laboratories, Albuquerque, New Mexico, USA (Degnan et al, 1995), and Pegasus situated at Los Alamos National Laboratory, Los Alamos, USA.…”

“…One should remember that, in the implosions of thick metal shells of the type used by Degnan et al (1995), the structural strength of the material can have a considerable stabilizing effect at the early stage of the implosion process. These effects have not yet been studied in great detail and we will not discuss them below.…”

“…This had been demonstrated in a multi-megajoule explosively driven experiment described by Mokhov et al (1979). More recently, quasispherical implosions in the Z-pinch geometry have been experimentally studied by Degnan et al (1995). A linear convergence ratio of -6-7 has been reached.…”