Development of a hybrid mode linear transformer driver stage

Abstract

At present, the mainstream technologies of primary power sources of large pulse power devices adopt Marx or linear transformer driver (LTD) designs. Based on the analysis of the characteristics of these two types of circuit topologies, the concept of a hybrid mode LTD stage based on Marx branches is proposed. The analysis shows that the hybrid mode LTD stage can realize the following goals: (a) to reduce the energy and power handled by the basic components (switch and capacitor) to lengthen their lifetime; (b) to reduce the requirements of the multipath synchronous trigger system; and (c) to improve the maintainability of the LTD stage by using independent Marx generators instead of “traditional LTD bricks.” To verify the technique, a hybrid mode LTD stage consisting of 50 branches (four-stage compact Marx generators) was designed, manufactured and tested. The stage has a radius of about 3.3 m and a height of 0.6 m. The single Marx circuit’s load current is about 21 kA, with a rise time of ∼90 ns (10%–90%), under the conditions of capacitors charged to ±40 kV and a 6.9 Ω matched load. The whole stage’s load current is ∼1 MA, with a rise time of ∼112 ns (10%–90%), when the capacitors are charged to ±45 kV and the matched load is 0.14 Ω.