The effects of an external magnetic field on Nd:YAG laser-produced Sn plasma have been investigated. The characteristics of ion debris from Sn plasma, emission spectra, and EUV radiation have been studied by the time-of-flight method and the optical emission spectroscopy. Our results show that the ion kinetic energies of the plume species can be effectively reduced with a modest magnetic field of 0.6 T. With the presence of a magnetic field, the spectral intensities of Sn I and Sn II show significant enhancement and the electron density of plasma is about 2 times higher. We have not found any influence of magnetic field on the characteristics of EUV emissions.

The transverse pumping geometry simplifies the laser system design by separating pump and laser beams and providing space for multiple diode laser pump sources with poor beam quality. A transverse pumping double-pass model for metastable rare gas lasers is presented in this paper, in which some intra-cavity information can be obtained. The comparison with Yang’s longitudinally pumped calculation results demonstrated the validity of our model. Several important factors having influence on optical conversion efficiency are simulated and discussed. Simulation of the effects of the required plasma size in transverse pumping model shows that a small size of $0.3\mathrm{cm}\times 10\mathrm{cm}\times 10\mathrm{cm}$ is capable of emitting 9 kW with an optical conversion efficiency over 55% and a megawatt-class output would only need an active medium of several liters if the metastable atoms concentration reaches $3\times {10}^{13}{\mathrm{cm}}^{-3}$.

A method to generate a broadband isolated attosecond pulse with stable pulse duration and high signal-to-noise ratio is proposed. By adopting a few-cycle driving pulse combined with its second-harmonic field of which the polarization angle is $\pi ∕3$ with respect to the driving pulse, the short path is well selected and a smooth supercontinuum with the bandwidth of about $50\mathrm{eV}$ is observed, which leads to 100-as single attosecond pulse generation with high signal-to-noise ratio. More surprisingly, the intensity variation of the second-harmonic field can hardly affect the location and the bandwidth of the generated supercontinuum but only slightly reduce its phase-locking degree. For the intensity of the second-harmonic field higher than ${10}^{14}\mathrm{W}∕{\mathrm{cm}}^2$, a pure isolated attosecond pulse with duration of about 100 as can be generated by directly filtering out a supercontinuum from $85–125\mathrm{eV}$, which facilitates the experimental implement of the isolated attosecond pulse generation.

Optically pumped metastable rare gas lasers have been extensively investigated as promising high-energy lasers. These systems employ discharge-excited metastable inert gases as the lasing medium. Following optical pumping, a buffer gas, typically helium, is introduced to facilitate a collisional population transfer to the p²[1/2]₁ level, thereby establishing population inversion. To date, laser outputs in the watt level have been demonstrated. However, further power scaling crucially depends on the ability to stably generate high metastable densities at elevated pressures approaching atmospheric conditions. In this Letter, we report a pulsed discharge technique based on a peaking capacitor rapid discharge circuit, which is capable of producing metastable particle densities exceeding 10¹⁴cm⁻³ at pressures up to 900 mbar. By employing this discharge approach in conjunction with transverse optical pumping, we have realized a maximum output power of 12.5 W from a semiconductor-pumped metastable argon laser system.

The present work reports an investigation of plasma expansion produced by Nd:YAG laser irradiating tin droplets. An intensified charged coupled device camera was used to record the plasma plume images, and the temporal evolution of the plasma plume was studied at various laser intensities. Our results demonstrate that the shape of the plasma plume develops from an approximate circle to an ellipse. The temporal evolutions of plasma boundary and plasma centroid were calculated by the secondary moment of plasma image intensity. The angle distributions of the plasma expanding velocity were obtained; the results show that the plasma expanding velocity decreases with increase of the angle to the incoming laser axis. In addition, the eccentricity of the plasma ellipse decreases with time. Meanwhile, we found that the centroid of plasma clusters moves toward the laser incoming direction during the expansion stage and the velocity of this motion is independent of laser intensity.