摘要:

An analytical potential calculation strategy is worked out, using the analytical solution of Laplace’s equation in cylindrical and toroidal configurations with rectangular sectional shape and rotation symmetrical boundary conditions. This strategy makes it possible to calculate the potential distribution to any desired rate of accuracy, even in very complex rotation symmetrical lens systems, and serves as a basis for the calculation of charged particle trajectories. These calculations only have to be done in places or areas where the shapes of the particle trajectories are of interest, while only and in a direct way the potential distribution on the boundaries of the potential volume is used in the calculations. Even in regard to the commonly used charge density method, this analytical calculation procedure saves a great amount of computer memory and calculation time, since no matrix inversions are required anymore.

ISSN:0021-8979    

DOI:10.1063/1.329962

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Applying a perturbation expansion to the self‐consistent Poisson equation for a planar, space‐charge‐limited crossed‐field diode, we have derived four universal diode functions (independent of any particular diode specification), in addition to the usual Fry‐Langmuir function for unperturbed, unmagnetized planar diodes. A crossed‐field diode is completely specified by three external parameters: its normalized widthX=xa/&lgr;Db, anode voltageV= &fgr;a/&fgr;Tb, and magnetic field &OHgr; = &ohgr;c/&ohgr;pb. Hereaandb, respectively, denote anode and cathode quantities, &lgr;Dbis the electronic Debye length, &ohgr;pbis the plasma frequency, &fgr;Tbis the electron temperature in volts, and &ohgr;cis the electron gyrofrequency. Evaluating the universal functions at abscissas appropriate for a particular set ofX,V, and &OHgr; then allows the calculation of the anode noise power (mean square current fluctuation at the anode) as a function ofX,V, and &OHgr;. The range of external parameters for which the theory is applicable is specified by a simple constraint relation forX,V, and &OHgr;, which ensures that the diode is space‐charge limited both with and without the applied magnetic field. The results of our analysis show that the noise level of a space‐charge‐limited diode increases monotonically from the reduced level at zero magnetic field. These results are for a range of magnetic fields well below the threshold where the diode enters the regime of magnetic‐field‐limited flow in which the noise power reaches the temperature‐limited level. Thus the range of the space‐charge‐limited regime studied is always associated with a reduced noise level which is, nevertheless, greater than the unmagnetized space‐charge‐limited level.

ISSN:0021-8979    

DOI:10.1063/1.331585

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We examine the feasibility of high power generation of visible radiation by a process of applying an axial accelerating electric field on electrons trapped in the ponderomotive potential of a Compton scattering free electron laser. We consider a scheme where the pump (wiggler) field is produced by a high‐power pulsed CO2laser and the signal wave is the radiation of a high‐power pulsed dye laser. We propose to use a hollow dielectric waveguide in order to overcome the pump wave diffraction and obtain a long interaction length.

ISSN:0021-8979    

DOI:10.1063/1.331586

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The experimental results of the inverted Lamb dip of a 633‐nm He‐Ne laser with a neon discharge‐absorption cell are compared with the theoretical results in detail. The rate equation approximation which is valid for a wide range of the saturation depth is used as a theoretical basis. After the fitting procedure, the theoretical curve approximates the experimental result in good agreement. The parameters, such as the central frequency, the homogeneous linewidth, and the saturation parameter are determined from the best‐fit condition. The 12±3‐MHz/Torr pressure shift of the central frequency of the laser transition is obtained for 5.3:1 He‐Ne mixture.

ISSN:0021-8979    

DOI:10.1063/1.331587

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We have developed a comprehensive computer code to analyze output performance of KrF laser excited by an intense electron beam. Especially for short pulse (<100 ns) and high excitation rate (≳1 MW/cm3) pumping, and under realizable conditions, we have calculated the intrinsic laser efficiency as a function of excitation rate. The results were compared with some experimental results which have been already reported by other groups, and a fairly good agreement was obtained. At an excitation rate of 1.5–2 MW/cm3, and at a total gas pressure of near 1.5–2 atm, an intrinsic efficiency of up to 11.5% is found to be attainable. At 3–4 atm, even at an excitation rate of near 7 MW/cm3, the efficiency of 9% is obtainable. We have also calculated the KrF* production efficiency and the laser extraction efficiency, and explained the output performance in terms of excitation rate.

ISSN:0021-8979    

DOI:10.1063/1.331588

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Ultraviolet light amplification by the phosphorous chemiluminescence flame is observed in the 200–400‐nm region. PO &ggr;‐system emission is identified in the light amplification spectrum. Gaps in the amplification spectrum are attributed to the forbidden transitions:4II→X2IIof PO at 30 590 cm−1and5&Ggr;1→1,3&Ggr;0of PO excimer at 28 117 cm−1. Light amplification by the phosphorus chemiluminscence system is interpreted as an incipient lasing action.

ISSN:0021-8979    

DOI:10.1063/1.331589

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The threshold current density of a stripe‐geometry GaAs double‐heterostructure laser has been calculated taking into account the influence of the dynamical processes occurring along the junction plane. The calculation includes the effects of a temperature profile, current spreading, carrier diffusion and optical mode losses. The junction current densityJ, which causes heat generation, is assumed to be temperature dependent. The interdependence between them is taken into account in a self‐consistent way. The temperature effect is shown to be particularly important for lasers with narrow stripe widths (<20 &mgr;m).

ISSN:0021-8979    

DOI:10.1063/1.331590

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Experimental study of the mode powering in an assortment of single‐mode lasers covering samples of most of the contemporary structures reveals a common property: the functional dependence on gain of the power in the strong mode. The high‐power asymptote is a linear function of the gain, while the low‐power asymptote of the light‐emitting diode (LED) state is linear in the reciprocal of the departure of the gain from its threshold value. The entire dependence is expressed by a universal dimensionless function of the gain, which is independent of laser structure, and which describes both asymptotes, provides a reasonable connecting link, and gives an experimental fiduciary of threshold. The fiduciary is the current at the sharp maximum in the logarithmic derivative of mode power with respect to junction voltage. Exerimental study reveals that this fiduciary corresponds closely to the conventional extrapolated threshold, with the inflection point in the junction resistance, and with the peak in noise. The universal function yields the dependence of power in the dominant mode on junction voltage given by the steady‐state solution of North’sP* theory. It is not consistent with the gain clamping at threshold that is described by familiar hole‐burning theories of injection lasers, which limit the lasing region to far too small a range of gain. The same function is found to describe a published measurement of the transition of threshold of an He‐Ne laser.

ISSN:0021-8979    

DOI:10.1063/1.331591

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A laser‐comparison method was used to determine the emission cross sections at 1060 nm of Nd glasses used in laser fusion systems. The values obtained for two phosphate glasses (LHG‐8) and (Q‐88) were 4.0±0.8×10−20cm2and 1.7±0.5×10−20cm2for a silicate glass (LG‐650).

ISSN:0021-8979    

DOI:10.1063/1.329911

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The use of volume sources, such as nuclear pumping, presents some unique features in the design of photolytically driven systems (e.g., lasers). In systems such as these, for example, a large power deposition is not necessary. However, certain restrictions, such as self‐absorption, limit the ability of photolytically driven systems to scale by volume. A photon transport computer program was developed at the University of Missouri‐Columbia to study these limitations. The development of this code is important, perhaps necessary, for the design of photolytically driven systems. With the aid of this code, a photolytically driven iodine laser was designed for utilization with a3He nuclear‐pumped system with a TRIGA reactor as the neutron source. Calculations predict a peak power output of 0.37 kW. Using the same design, it is also anticipated that the system can achieve a 14‐kW output using a fast burst‐type reactor neutron source, and a 0.65‐kW peak output using 0.1 Torr of the alpha emitter radon‐220 as part of the fill. The latter would represent a truly portable laser system.

ISSN:0021-8979    

DOI:10.1063/1.329912

出版商:AIP    

年代:1982

数据来源: AIP