Use of multi-mega ampere currents to drive matter into extreme states
Supervisor: Dr Simon Bland, Co-Supervisor: Professor Sergey Lebedev (Plasma Physics Group)
The behaviour of dense matter subjected to very high pressures is interesting to a number of physical disciplines, for instance, the modelling of planetary cores, the effects of meteor and comet impacts and the compression of inertial confinement fusion capsules. Recently progress in the field has been greatly accelerated through the use of high current pulsed power generators to apply an increasing magnetic pressure to a target without inducing shocks - 'ramp loading'. This has allowed pressures of ~5Mbar to be directly applied to materials in Isentropic Compression Experiments (ICE) on the Z generator at Sandia National Laboratories; and has allowed cm scale Flyer plates to be launched into materials at velocities >25kms-1 producing highly uniform >10Mbar shock fronts.
At Imperial College we are also exploring using pulsed power to generate shocks and very high pressures for high energy density physics research. The PhD will involve developing ramp and shock loading techniques on both the 2MA MAGPIE generator, and the new 2MA MACH generator, which is being built as part of the Institute of Shock Physics programme at Imperial College and will allow highly accurate shaping of the output current pulse. The targets involved will initially be low Z solids (e.g. A1), then liquids and gases - and through use of some fraction of the current of either generator - low and high density plasmas.
Different methods to ramp and alter the spatial profile of the pressure applied to a target will be examined and the launching of various types of shock waves through targets explored - including radiative shock waves being launched through low density plasmas. Methods to further increase the availability pressure through focusing of shocks will be studied and the development of hydrodynamic instabilities over long time scales will be observed.
The student will be trained in the use and development of different diagnostics which are commonly used in pulsed power and shock research studies, e.g. het-V, point and line VISAR, pyrometry, fast optical and X-ray streak techniques and X-ray radiography. The student will be based primarily at Imperial College and work on the MAGPIE and MACH pulsed power facilities. He will interact closely with the Hydrodynamics Group at AWE and it is envisaged that the student will also participate in the experiments at Sandia National Laboratories.