An Experimental Platform for Cylindrical Liner Implosions on the M3 Pulsed-Power Facility

Liner implosion experiments offer a diverse range of applications, from testing of materials at extremes of pressure, to compression of plasmas to nuclear fusion-relevant densities and temperatures. A liner-driven target concept is being pursued as part of First Light Fusion’s inertial fusion energy scheme, motivating the development of a liner implosion platform for M3: a 10MA peak current, 2µs rise time pulsed-power machine housed onsite.

We present experimental results from this platform, which utilises an 8mm radius aluminium cylindrical liner that impacts onto a central PMMA sample. Several different load geometries of varying inductances were tested, and the impact time onto the PMMA sample measured using backlit optical shadowgraphy. The shock velocity and uniformity in the PMMA was assessed, making use of 2D simulations run using our in-house magnetohydrodynamics code B2 to interpret the results.

Radial photonic doppler velocimetry (PDV) was also fielded to obtain the velocity history of the inner liner surface, tracking the implosion up to 8.5km/s at a radius of 4.6mm. Machine current measured with a Faraday rotation diagnostic was used alongside the PDV data to compare against predictions made using B2, allowing for an improved understanding of the machine coupling to the load. The results of this analysis are discussed, and design choices for future liner geometries are also highlighted.