March 13, 2014
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HAPLS Diode Power Delivery System Components Demonstrated

By Charlie Osolin

The first demonstration of components of the short-pulse diode-pumped solid-state laser (DPSSL) system for the High Repetition-Rate Advanced Petawatt Laser System (HAPLS) has been conducted. HAPLS, which when complete will be the world’s highest average power petawatt laser system, is being designed, developed, assembled and tested at LLNL for delivery to the European ELI-Beamlines science facility in the Czech Republic.

A key component of a DPSSL is the diode power conditioning required to drive the 3.2 megawatts of diode light used to pump the gain media of the laser. The diodes consist of four arrays with each array having 45 laser diode tiles, which need to be driven at a pulse current of 500 amps for 300 microseconds at 10 cycles per second (10Hz). To deliver the required current to drive HAPLS’ 180 laser diode tiles, the HAPLS Power Conditioning Team developed an integrated system consisting of diode pulsers, a real-time control system, a crate to house the pulsers and controller, and low-loss cables to deliver the current pulses to the diode tiles.

The pulser crate is an aluminum structure about the size of a desktop computer which houses up to 45 pulsers. When fully populated with pulsers, the crate will be capable of delivering 45,000 amps of current at a 10-Hz rate to a pump diode array. For the demonstration, a crate with 12 pulsers was operated at full current and voltage, delivering 6,000 amps into resistive loads. The crate was then delivered to the HAPLS diode vendor to perform tests on the diode tiles that will be used in the HAPLS laser.