Pulsed-coil magnet systems for applying uniform 10–30 T fields to centimeter-scale targets on Sandia's Z facility

Abstract

Sandia has successfully integrated the capability to apply uniform, high magnetic fields (10-30 T) to high energy density experiments on the Z facility. This system uses an 8-mF, 15-kV capacitor bank to drive large-bore (5 cm diameter), high-inductance (1-3 mH) multi-turn, multi-layer electromagnets that slowly magnetize the conductive targets used on Z over several milliseconds (time to peak field of 2-7 ms). This system was commissioned in February 2013 and has been used successfully to magnetize more than 30 experiments up to 10 T that have produced exciting and surprising physics results. These experiments used split-magnet topologies to maintain diagnostic lines of sight to the target. We describe the design, integration, and operation of the pulsed coil system into the challenging and harsh environment of the Z Machine. We also describe our plans and designs for achieving fields up to 20 T with a reduced-gap split-magnet configuration, and up to 30 T with a solid magnet configuration in pursuit of the Magnetized Liner Inertial Fusion concept.

Effects of magnetization on fusion product trapping and secondary neutron spectra

“…These are: (1) magnetization, shown in Fig. 2(a), where a slowly rising, axial B-field is applied to the target using a Helmholtz-like coil 19 and allowed to diffuse throughout the liner and fuel, which has an initial density of $0.5-1.5 mg/ cm 3 ; (2) laser heating, shown in Fig. 2(b), where the multi-kJ Z-beamlet laser is fired into the fuel through a Laser Entrance Hole (LEH), heating the fuel to 100-200 eV; and (3) compression, shown in Fig.…”

Demonstration of thermonuclear conditions in magnetized liner inertial fusion experimentsa)

“…2(a) in Ref. 33), and the relatively high initial target inductance. The peak current in experiments with 10 mm active height targets was typically 1 MA less than in experiments with 7.5 mm active height targets.…”

“…30,31 ZBL is a TW-class, multi-KJ, frequency-doubled (527 nm) Nd:glass laser. 32 The ABZ system consists of a 900 kJ capacitor back and a pair of Helmholtz-like coils, which can magnetize cm-scale targets to 10-30 T. 33 Fully integrated MagLIF experiments utilize all three of these capabilities.…”

Evolution of sausage and helical modes in magnetized thin-foil cylindrical liners driven by a Z-pinch

“…1 The dumbbell-shaped support structure was used to allow the foil to implode so that the MHD modes could couple to the MRT instability. 2 The liner loads were axially magnetized to B z ¼ 0.5 -2.0 T using two 80-turn Helmholtz-like coils 19 driven by a separate and independent capacitor bank (1.2 mF, 2.0 ms quarterwavelength risetime). The two coils were separated by 2.54 cm and were situated outside of the return current can, positioned above and below the liner region to generate a spatially uniform axial magnetic field over the entire liner region (see Ref.…”