Ru原子高Rydberg态研究

本文描述用激光共振激发-场电离实验方法测定Ru原子的4d⁷(⁴F)ns(n=28—45)和4d⁷(⁴F)nd(n=26—48)系列Rydberg能级,并应用非线性拟合得到了Ru原子的第一电离阈值。采用相对论性自洽场方法对所得能级以及相应的量子亏损作了计算,理论与实验结果符合得很好。此外还将本文所得的第一电离阈值与已有数据作了比较。 关键词：     

用多步激发技术测定锶的(5p3/2ns)1及(5p3/2nd)3自电离谱

用分步激发方法及偏振光技术,测定了锶的(5p_3/2ns)₁(n=13-21)及(5p_3/2 nd)₃(n=13-24)各自电离谱,在低于5p_1/2电离限的(5p_3/2ns)₁态的实电子激发谱中,出现对应于(5p_1/2ns)₁及(5p_1/2nd)₁的畸变峰,畸变峰也出现于(5p_3/2nd)₃的实电子激发谱中。这说明(5p_jns)(5p_jnd)自电离系列间存在相互作用。 关键词：     

用脉冲电场光电流光谱研究Ne原子的自电离态

本文用脉冲电场光电流光谱的实验方法测定Ne原子ns＇(n=15—31)和nd＇(n=13—30)两通道的35条自电离态能级,用参数拟合得出Ne原子ns＇和nd＇通道的电离阈值,计算了每条能级的量子亏损,实验用脉冲电场代替直流放电,基本上消除了Stark效应在光电流光谱测量中的影响。 关键词：     

Sr(5p1/2nd)3自电离谱的测定

用分步激发技术测得了Sr(5p_1/2nd)₃系列(n=11—24)自电离能级的位置及其有效量子数ν_1/2。对其与(5p_3/2nd)₃,系列间可能存在的组态相互作用,进行了初步探讨。 关键词：     

Na原子高里德堡态的辐射寿命

用可调谐激光两步激发Ｎａ原子高激发发里德堡态布居，在光激发后施加脉冲电场测量激发态的场电离阈，利用阈值电场和延迟场电离方法测定了ｎｓ（ｎ＝２０～２４）和ｎｄ（ｎ＝１９～２３）态的寿命值，并与计算值进行了比较，对影响寿命的因素作了讨论。     

Excitation of sodium atoms by 330-nm laser pulses

1/2 ) atoms in a dense sodium vapour irradiated by nanosecond laser pulses tuned near the 3S→4P transition was investigated. It was observed that the population of Na(4P) atoms remained high only within the laser pulse, in spite of the relatively long lifetime of the 4P level (110.ns)The 3P_1/2 level, which is populated as a result of cascade transitions from the higher levels, reached the highest population several nanoseconds after the laser shot. The fast population changes are explained by cascade-stimulated transitions between the excited atomic levels. Received: 16 July 1997/Revised version: 27 October 1997     

High power Q-switched Yb-doped photonic crystal fiber laser producing sub-10 ns pulses

We report on a Q-switched fiber laser producing pulse durations well below 10 ns by using a short-length ytterbium-doped rod-type photonic crystal fiber as gain medium. At repetition rates up to 100 kHz pulse energies up to 0.5 mJ and average powers in excess of 30 W have been obtained in single-transverse mode beam quality. The compact short pulse laser system possesses further power and energy scaling potential.     

Prepulse dependence ofJ=0−1 lasing at 32.6 nm in neon-like titanium

The dependence of the intensity of the 3p—3s,J = 0–1 lasing line at 32.6 nm in neon-like titanium on the prepulse level has been investigated experimentally. Titanium slabs were irradiated with 1.315 µm/450 ps pulses from the Asterix IV iodine laser using a defined prepulse of 5.2 ns before the main pulse. It is found that for pump energies close to the minimum energy for which lasing is observed, a prepulse level of order 0.5% gives the highest XUV laser intensity, whereas a higher prepulse level, of order 10% and more, is required for optimum XUV lasing far above the threshold. For a 2.7 cm long titanium target lasing was observed down to a pump irradiance of 2.5 TW/cm² (50 J/450 ps) for the 0.5% prepulse.     

The first target experiments on the National Ignition Facility

A first set of shock timing, laser-plasma interaction, hohlraum energetics and hydrodynamic experiments have been performed using the first 4 beams of the National Ignition Facility (NIF), in support of indirect drive Inertial Confinement Fusion (ICF) and High Energy Density Physics (HEDP). In parallel, a robust set of optical and X-ray spectrometers, interferometer, calorimeters and imagers have been activated. The experiments have been undertaken with laser powers and energies of up to 8 TW and 17 kJ in flattop and shaped 1–9 ns pulses focused with various beam smoothing options. The experiments have demonstrated excellent agreement between measured and predicted laser-target coupling in foils and hohlraums, even when extended to a longer pulse regime unattainable at previous laser facilities, validated the predicted effects of beam smoothing on intense laser beam propagation in long scale-length plasmas and begun to test 3D codes by extending the study of laser driven hydrodynamic jets to 3D geometries.     

Investigation of XeCl vibrational and quenching kinetics: Numerical simulation of gain and laser spectra in discharge-pumped oscillators

Model calculations of the small-signal gain and laser spectra and of laser output energies have been performed for various discharge-pumped XeCl laser systems. From comparison between model and experiment, limits have been set for the rate coefficients for XeCl(B,C) quenching by Ne, Ne + Xe and electrons. The influence of non-stationarity and electron-electron collisions in the solution of the Boltzmann equation on the estimation of these rate coefficients has been investigated. Some rough estimates of the XeCl(X,v) dissociation rate coefficients are given. It is shown, that due to the inclusion of bound-free emission from the XeCl(B, = 1) level it is not necessary to include strong variations of these rate coefficients with the vibrational quantum number to reproduce the intensity ratios of the two laser lines observed in free-running XeCl-excimer lasers.