Fiber-optic triggering of a two-stage high-current linear transformer driver with laser energy below 100 μJ

Nanosecond-level synchronization of a large number of spark gap switches is one of the challenges in building large-scale linear transformer drivers (LTDs). A method using LTD cavities internally integrated with fiber-optic controlled trigger bricks is proposed to simplify the topology of the trigger system. To verify the feasibility of this trigger method, a two-stage LTD is developed with two fiber-optic controlled trigger bricks. The core component of the trigger brick is a ±80 kV fiber-optic controlled spark gap switch, which integrates a DC bias avalanche photoconductive semiconductor switch and a four-gap field distortion spark gap switch. This switch can be reliably triggered over 3000 shots with a jitter below 3 ns at laser energy below 100 μJ and exhibits no self-discharge. The two-stage LTD is synchronously triggered for 180 shots under a bipolar DC voltage of ±60 kV, generating an output current of ∼240 kA with a jitter of less than 3 ns. The proposed trigger method demonstrates potential for extension to multi-stage LTD modules.