Short intense hydrogen gas pulses for transport studies in fusion plasmas produced by laser thermal desorption from titanium hydride

The suitability of laser thermal desorption (LTD) from titanium hydride targets for the production of short intense hydrogen gas pulses for diagnostic applications in fusion devices was investigated. A hydrogen yield of 2.2×1018 H2 molecules was achieved with a pulse energy of 11 J on a target spot diameter of 4.5 mm. The duration of the gas puff is closely coupled to the laser pulse length of 1 ms. The production of gas pulses by LTD close to the plasma creates the requirements for investigating very fast transport processes, especially at the high‐field side. The hydrogen pulses were contaminated by 2×10−3 Ti atoms/H2 molecule, primarily as a result of evaporation on overheated surface inhomogeneities. Conditioning the surface with giant laser pulses allowed the contamination to be reduced by a factor of 2.