Ultrahigh magnetic fields produced in a gas-puff Z pinch

Abstract

C:0ntrolled, ultrahigh axial :naglletic fields have been produced and measured in a gas-puff Z pmch. A O.S-MA. 2-cm-radlus annular gas-puff Z pinch with a 3-min repetition rate was imploded radially onto an axial seed field, causing the field to compress. Axial magnetic field com~ressions up to 180 and peak ~agnetic fields up to 1.6 MG were measured. Faraday rotation of an Argon laser (5154 A) in a quartz fiber on-axis was the principal magnetic field diagnostic. Other diagnostics included a nitrogen laser interferometer, x-ray diodes, and magnetic field probes, The magnetic field compression results are consistent with simple snowplow and self-similar analytic models, which are presented here. Even small axial fields help stabilize the pinches, some of which exhibit several stable radial bounces during a current pulse. The method of compressing axial fields in a gas-puff Z pinch is extrapolable to the order of 100 MG. Scaling laws are presented. Potential applications of ultrahigh axial fields in Z pinches are discussed for x~ray lasers, inertial confinement fusion, gamma-ray generators, and atomic physics studies. 3831

Effect of Wire Diameter and Addition of an Axial Magnetic Field on the Dynamics of Radial Wire Array $Z$-Pinches

“…Estimates of the compression of the axial magnetic flux at the time of pinching result in B Z ∼ 200 T, which is a factor ∼100 of the initial vacuum axial magnetic field generated from the solenoids. This effect is similar to the results obtained by introducing an axial magnetic field in a gas-puff Z-pinch [13]. We also note that the compression of an axial magnetic field by the implosion of cylindrical wire arrays was studied in [15].…”

“…The addition of an axial magnetic field could aid the stabilization of the plasma column on the axis of the cavity, delaying the formation of current-driven instabilities at the time of pinching [13], [14].…”

Magnetic flux and heat losses by diffusive, advective, and Nernst effects in magnetized liner inertial fusion-like plasma

“…Normalizing the effective transverse diffusivities with respect to D B (in (71) we put T ¼ T 0 , B ¼ B 0 ), and noticing that the transverse heat diffusivity is expressed from (10) and (35) as…”

“…We can try a similar estimate for a magnetized plasma, replacing v k0 with v ?0 in (43) and using (10) to evaluate the reduction of heat diffusivity due to magnetization. When the value of electron Hall parameter far from the wall is varied from 10 to 200, the corresponding reduction of the thermal diffusivity is given by a factor varied from 0.037 to 6.6 Â 10 À4 .…”

“…Þ n j is evaluated using T n jþ1=2 ¼ 1 2 T n j þ T n jþ1 À Á , and similarly for magnetic field and density. The transport coefficients are evaluated using the full Braginskii's expressions (10). The Coulomb logarithms, however, were kept constant throughout the run…”