Prototype IVA module (PIM)

As a result of the Pulsed Power Group´s programme to gain expertise in IVA (inductive voltage adder) technology we have designed a prospective module for a future large IVA machine that would be suitable for full scale radiography at AWE. This machine would operate at 13 to 15 MV. The PIM machine has been built at AWE to test a single such module and we have been collecting performance data from it before fixing the design for the full size machine. PIM also provides the basis for the PPG´s continued research programme in this area and hence possible other machines for the future. The PIM machine consists of a single inductive cavity pulsed by a water dielectric Blumlein pulse forming line which is charged by a Marx generator. The Marx generator is based on the Sandia hanging Marx design. It is constructed using 32 1.35 uF 100 kV DC capacitors. The Marx pulse charges the 10 ohm water Blumlein. which acts as a fast pulse forming section. The Blumlein switch initially installed was a co-axial two stage rimfire and trigatron switch. A laser triggering configuration utilising two radial switches, designed by Titan PSI, is also to be tested. The inductive cavity incorporates ferromagnetic cores formed from Metglas alloy tape and the fast pulse appears across a perspex (lucite) insulated accelerating gap. The pulse travels along a short vacuum transmission line to a ball/plane e-beam diode test load. Work has been carried out to test the module design. Initially the Marx was characterised into a resistive load to establish its operating regime. The Blumlein PFL and its Rimfire/Trigatron switch were then tested, also using a copper sulphate load. A peak output voltage of 1.7 MV was achieved from the PFL. The inductive cavity has been added and we are in the process of testing it. A pulse of 1.4 MV peak voltage has been successfully applied to it. The latest details of the system´s characterisation are presented.