Excitation mechanism and plasma parameters in pulsed argon-ion lasers

Pulsed argon-ion lasers show several interesting properties at high currents. To understand the inversion mechanism, the plasma parameters, electrical conductivity, electron temperature, and electron density were measured with the double-probe method for the pressure range from 15 to 50 mtorr in a 6-mm-bore tube. When the discharge current increases from 100 to 700 amperes at the optimum pressure for laser oscillation, these parameters increase from 250 to450Omega^{-1}cdotcm^-1, from8 times 10^{4}to10^{5}degK, and2 times 10^{14}to 10¹⁵cm^-3, respectively. At the maximum electron density, the percent of ionization appears to be in excess of 100 percent, as a result of the pinch effect and double ionization. It is certain that this ring discharge is at least ionized very strongly. In a 10-mm-bore tube, only the electron temperature and density were measured. The current dependence of the laser output power at high currents is interpreted with those results. Excitation mechanisms of high-current argon-ion lasers are discussed with experiments and theories for strongly ionized plasmas.     

Properties of argon-ion lasers in Ar-He gas mixtures

When helium is added to argon, the relative peak intensity of the 4880-Å pulsed argon-ion laser scarcely decreases even at high currents whereas in pure argon it decreases remarkably after saturation. It is supposed that the changes of the neutral atom and ion densities contribute to the phenomenon.     

Characteristics of pulsed discharges in copper bromide and copperHyBrID lasers

Comparative measurements of discharge electrical waveforms have been carried out with a Ne-H₂-CuBr laser, a Ne-CuBr laser, and a Cu HyBrID laser, each of the same size and geometry, and under the same conditions of excitation. From the general similarity of the electrical characteristics of the HyBrID laser and the Ne-H₂-CuBr laser, together with a reappraisal of the role of hydrogen, it is concluded that the main characteristics of these lasers (high efficiency, high average output power, and special features of their excitation pulse waveforms) can all be qualitatively explained if we assume that HBr and not hydrogen (molecular, atomic, or ionic) is the responsible agent which acts via the process of dissociative attachment of electrons to HBr during the interpulse period and during the early stages of the discharge current pulse     

Electrical resistivity of noble gas pulsed discharges

The electrical resistivity of pulsed discharges in flash-tubes using noble gases is treated in a simple manner. Relations between resistivity and electric fieldEand current densityjare given. It is shown that electrical resistivity in pulsed discharges is an inverse function ofjorE, depending also on an exponentnwhich does not remain constant during the discharge.     

用于提高国产氩离子激光器相干长度的相干扩展器

本文报导了最近研制成功的用于提高国产氩离子激光器相干长度的相干扩展器。利用这种基于F-P理论的相干扩展器可以使国产氩离子激光器的相干长度由不足5cm一下提高到m的量级,功率损耗在25%～40%之间,有着很好的应用前景。     

Spectroscopic studies of gas discharges used for argon ion lasers

Characteristics of argon discharge which are relevant to the operation of Ar⁺lasers are investigated. These include ion and electron densities and ion temperatures as a function of current density.     

Preionization of pulsed gas lasers by radioactive source

An α-source of americium-241 is used to preionize transverse electrical-discharge gas lasers, enhancing the useful pressure range in a variety of gases. Of particular interest is the enhancement in electron-attaching gases, which corroborates speculations on the role of negative ions in preionization.     

脉冲气体激光器磁压缩放电电路的仿真

为了降低用于脉冲气体激光器的全固态磁压缩放电电路的放电延时抖动,采用PSPICE软件对全固态磁压缩激励电路进行仿真分析,完成了对充电、磁开关复位以及整个放电过程的初步模拟。模拟结果显示,初始储能电容电压1V的波动会引起放电时间5ns~10ns的抖动,抖动时间随着充电电压的升高而降低;通过采用特制的两级耦合复位回路来降低放电延时抖动,该复位电路可将放电抖动从微秒量级降低到纳秒量级。结果表明,降低抖动的关键因素在于充电过程中高频交流纹波经复位电路耦合将磁芯复位到一稳定状态,使磁开关、可饱和脉冲变压器的工作状态更加稳定。建立的仿真模型,对低放电抖动的脉冲放电激励电路设计可提供参考。     

New method for detecting transient gain (or loss) in pulsed gas discharges

A pulsed argon discharge inside a CW-laser cavity is used to modulate the CW-laser output via the transient gain/loss at various lasing wavelengths. Under short-pulse excitation (sim 0.6 mus), gain is found at four Ar(II) lasing lines, but losses are observed at 4880 and 5017 Å. A similar diagnostic device with broad-band capabilities and based on an ion-laser-pumped dye laser is proposed.     

On the inversion mechanism in the CW argon-ion laser

Temperatures and densities of atoms and electrons were obtained by spectroscopic methods in a gas discharge plasma used for CW ion-argon lasers. The measurements were carried out with capillaries 250-400 mm long with a bore diameter of 1.6-2.8 mm. The filling pressures were 0.2-0.7 torr and the discharge current densities 100-500 A/cm². Electron temperatures were found from measured side-on widths of ArII lines using the Kagan-Perel theory. The electron densities were determined from the width of the Hβline and from electro-conductivity. The ionization rate was evaluated through the Doppler shift of spectral lines as well as through half-widths of the ArII lines taken along the discharge. For this purpose, the Kagan-Perel theory was used also. Population rates of the4s, 5s, 4p, 3d, and4dArII configurations of the ion ground state were calculated as well as radiation transition probabilities. With the aid of these data, population rates and densities were found for the doublet term system of configurations4sand4p. Population inversion was also evaluated. A comparison of the results of calculation with the experiment was carried out.     

CW gain measurements in small-bore argon-ion laser discharges using a novel modulation technique

A technique for small-signal gain measurements for CW laser systems is described. The method is applied to the measurement of multimode small-signal gain coefficients of small-bore argon-ion laser transitions.     

The time dependent resistance and inductance of the electricdischarges in pulsed gas lasers

A method of finding the time dependent resistances and inductances in the discharges in pulsed gas lasers is described in this work. According to this method the waveforms of the laser circuit voltages are digitized and their first and second derivatives are calculated. These are substituted into the differential equations governing the behavior of the system and relationships among the resistances and inductances are formed for every time. Using relationships from a sequence of four very closed adjacent time instants and considering that during this short time interval the resistances and inductances are varied linearly, their values can be found for this particular time interval. Repeating the same procedure for other time intervals and scanning the entire time region of the discharge, the time histories of the resistances and inductances of the discharges are revealed. These show strong variations in the “formation phase” of the discharge (first 50 nsec). Specifically the resistances drop rapidly (first 10 nsec) from very high values to low values, while the inductances increase to high values and subsequently decrease, forming an abrupt high peak. The steep drop of the resistances is due to the electron avalanche multiplication, while the peak of the inductances is due to the centripetal magnetic forces (Laplace forces), which cause a temporary constriction of the plasma. In the “main phase” of the discharge the resistances present a damping oscillation with the same frequency as the voltages, while the inductances present light fluctuations around constant values     

可控硅开关型脉冲激光电源

建立了开关型脉冲激光电源的数学模型并给出了设计方法。采用快速可控硅做为开关元件完成了一台容量为55kW、重复频率可达200Hz的脉冲激光电源,给出了具体的电路并进行了分析。     

New cold cathode for pulsed ion lasers

A simple, reliable high-current indium cold cathode for pulsed ion lasers is described. Currents in excess of 2000 amperes and pulse durations of 10^-2second have been obtained. Pulse repetition rates and operational lifetime appear to be limited only by the dynamics and lifetime of the discharge tube.     

High repetition rate pulsed gas lasers and their applications in chemistry and isotope separation

Presented in this paper are the results of experimental studies of pulsed high repetition rate XeCl, CO2, NH3, and CF4lasers with a closed gas cycle. Some applications of these lasers in chemistry and isotope separation are discussed.     

Plasma electronics in pulsed nitrogen lasers

A detailed study showing that the electronic impedances of both the spark gap and the laser channel plasmas play an integral part in the overall discharge circuit of a pulsed nitrogen laser is presented. The electronic properties of these plasmas can critically determine the temporal width of the laser pulse     

高功率脉冲激光的体吸收卡计

研制了以中性有色玻璃为吸收器的固体体吸收卡计,用于波长从0.4微米1.1微米,能量从1焦耳到50焦耳脉冲激光的能量测量,绝对测量的精度为±5%.卡计采用电加热校准,校准的重复性优于±0.5% .     

Laser oscillations at submillimetre wavelengths from pulsed gas discharges in compounds of hydrogen, carbon and nitrogen

Stimulated emission at ten new wavelengths between 126 and 373?m was obtained with dimethylamine. The stronger lines were also obtained with seven related compounds and with several mixtures, notably methane and ammonia. A new spectrum (four lines between 181 and 205?m) was obtained with a mixture of deuterium and bromine cyanide. The radiation is tentatively attributed to HnCN with n >1.     

Noise characteristics in repetitively pulsed semiconductor lasers

Timing jitter (phase noise) and power fluctuations (intensity noise) in a semiconductor laser driven with a periodic current waveform, in the large signal regime are investigated theoretically. The temporal behavior of the laser output power is calculated numerically from the modified rate equation with Monte Carlo simulation of the random processes, both free-running and active mode-locked configurations are treated. The temporal width and root-mean-square (rms) timing jitter and energy fluctuation of the pulses are calculated, as are the correlation and spectral properties of the noise     

脉冲强预燃及其对激光光泵效率的影响

本文介绍用于重复率固体激光器的脉冲强预燃技术.给出恒定弱预燃和脉冲强预燃的实验结果.经采用脉冲强预燃后,激光器可获得高效率和高功率输出.