First high radiant energy xenon-pipe-based x-ray source on LMJ

Abstract

We report on the performance of the highest radiant energy x-ray source at the LaserMegaJoule facility (LMJ) for testing material properties under irradiation. This radiation source was produced by the L-shell emission of xenon contained in a gas-pipe. The target was an epoxy ortho-cylinder tube with a diameter of 3 mm and a 50-μm thickness wall containing xenon gas at 1.2 atm. For this proof of principle shot, the LaserMegaJoule facility delivered a total energy of around 90 kJ of 351 nm laser and a total power of 30 TW. Thirty-two beams, divided into eight beamlets each, are arranged into two cones. The laser pulses were nearly flat, with a duration of 3 ns and a power range of 3.5–5 TW for each quadruplet. Two broadband spectrometers, DMX (DP4) and miniDMX (DP11), have been used to characterize the x-ray emission up to 10 keV. Radiant energy up to 0.5 kJ/sr has been recorded in the xenon L-shell band between 3 and 6 keV. This was the highest energy ever delivered for creating an x-ray source on the LMJ. Even though the target was axisymmetric, the strong asymmetric laser irradiation (nor axi or bottom/top symmetric) required full 3D radiation-hydrodynamic calculations to retrieve the radiant energy measured by broad band spectrometers. The main purpose of this work was to benchmark our 3D hydrorad code and the non-local thermodynamic equilibrium model by using newly developed x-ray spectrometers.