The MAGPIE project: Current status

A Mega-Amρere Generator for Plasma Implosion Experiments (MAGPIE) is currently under construction in the Plasma Physics group at Imperial College, London. The generator is specifically designed to carry out radiative collapse experiments in hydrogen fibre Z-pinches [1]. In order to achieve this goal, MAGPIE must be capable of delivering in excess of 1.5MA into a 150nH load in under 200ns. An artist impression of MAGPIE is shown in fig.1. In the final generator, four 2.4MV Marx banks charge four 5 ohm, coaxial, 100ns single transit, water filled pulse forming lines (PFLs). The four PFLs are connected to a single coaxial vertical transfer line via four synchronously triggered trigatron switches. The vertical transfer line has an impedence of 1.25ohm and therefore represents a matched load to the four PFLs. At the top of the transfer line a graded insulator stack makes up the vacuum-water interface. A magnetically insulated transmission line section then feeds the load. The total energy stored in the banks is 336kJ making MAGPIE a multi terrawatt, long pulse generator. This paper reports on the general status of the programme and on details of the work carried out in characterising and optimising the trigatron switches.