Development of laser-produced plasma light source with free electron laser

我们测量了稀有气体团簇和氦原子在强极紫外光自由电子激光脉冲照射下的荧光光谱。对于Ar原子团，我们在比51 nm的入射自由电子激光波长短的荧光波长下观察到丰富的结构。结果表明，在Ar团簇的纳米等离子体中，多电荷离子重新俘获等离子体电子。对于He气体，我们发现随着He原子密度的增加，荧光强度呈非线性增加。

We have measured fluorescence spectra of rare-gas clusters and helium atoms irradiated intense extreme-ultraviolet free-electron laser pulse. For Argon clusters, we observed rich structure at fluorescence wavelength shorter than incident FEL wavelength of 51nm. It is suggested that multiply charged ions recapture plasma-electrons in nanoplasma of the Argon cluster. For He gas, we found that fluorescence intensities nonlinearly increase with increasing the He atomic density.