Challenge of new extreme material science using high-energy THz source

利用超短强激光脉冲和脉冲放电产生的受控等离子体，实现了台式太赫兹电磁波源和极紫外光源。太赫兹辐射可以通过由激光产生的电离前沿产生的突发电流来产生，该电离前沿是在具有静电场的空气中引起的光场诱导电离。实验结果与理论计算结果基本一致，电场幅值随外加电压的增加而增大。我们还展示了一个放电产生的微等离子体极紫外源的基础上，一个纯钾蒸气。钾离子在40 nm附近产生强的宽带发射，带宽为8 nm [半高宽（FWHM）]。微放电的电流-电压特性表明，该电源工作在空心阴极模式。通过与原子结构计算结果的比较，发现宽带发射主要是由于K^<2+>到K^<4+>范围内的钾离子的3d-3 p跃迁。

We have demonstrated table top terahertz electromagnetic wave source and extreme ultraviolet light source by using a controlled plasma produced by an ultrashort, intense laser pulse and pulse discharge. The terahertz radiation can be generated by the burst current produced by a laser created ionization front, which is induced an optical-field-induced ionization in air with a static electric field. The experimental results behave similarly to calculated results, and electric field amplitude of THz radiation increase with increase in applied voltage of a static electric field. We also have demonstrated a discharge-produced microplasma extreme ultraviolet source based on a pure potassium vapor. Potassium ions produced strong broadband emission around 40nm with a bandwidth of8 nm [full width at half-maximum (FWHM)]. The current-voltage characteristics of microdischarge suggest that the source operates in a hollow cathode mode. By comparison with atomic structure calculations, the broadband emission is found to be primarily due to 3d-3p transitions in potassium ions ranging from K^<2+> to K^<4+>.