Abstract:
When developing a laser-plasma source of EUV radiation, an important criterion for selecting a target is the proportion of laser radiation energy absorbed by it. In this work, we measured the absorption of radiation from Nd:YAG lasers with a pulse duration of 3.8–12.5 ns, pulse energy of 0.2–0.8 J during laser breakdown of supersonic gas jets formed when gas flows through a supersonic conical nozzle with a critical section of 500 $\mu$m, a length of 5 mm and an aperture angle of 9$^\circ$. Gas-jet targets of molecular (CO$_2$, CÍF$_3$, CF$_4$, N$_2$) and inert (Ar, Kr, Xe) gases were studied. The integral and time dependences of the absorption of laser radiation by the target on the gas pressure at the nozzle inlet and the laser pulse energy were studied. The proportion of absorbed laser energy ranged from 25 to 85% for different gases at nozzle inlet pressures of up to 25 bar.
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