摘要:

A cw CO2laser operating on theR(30) 9‐&mgr;m transition is down shifted by 180 MHz in a pair of acousto‐optic modulators, and used to optically pumpsR(5,0) transition of NH3at line center. Vibrational inversion is created in the &ngr;2mode, and cw oscillation is observed on 20 different NH3lines, spanning the region between 10.7 and 13.3 &mgr;m. Single line output powers as high as 760 mW were measured in a waveguide cavity. The operation of this laser is explained using a simple thermalization model, and several potential applications are discussed.

ISSN:0003-6951    

DOI:10.1063/1.94781

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

Infrared pulses were generated over the range from 1.2 to 10 &mgr;m in a single path system consisting of two AgGaS2crystals. A high photon conversion efficiency between 10−1and 10−3was found depending upon the emission frequency. A bandwidth of approximately 10 cm−1for idler pulses between 6 and 10 &mgr;m was observed. With a Nd:yttrium aluminum garnet laser pump of 20‐ps pulse duration one observes parametric pulses of 8 ps.

ISSN:0003-6951    

DOI:10.1063/1.94782

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The utilization of coherent traveling electromagnetic waves to accelerate charged particles has been investigated. In the visible frequency region, electrons can be accelerated to energies in the range of 0.1 GeV within distances of 100 &mgr;m for electric fields of 6×1013V/m. The Rayleigh region of a near diffraction limited laser beam provides the high power densities and proper ‘‘turn‐off’’ to accelerate electrons. The use of masers as drivers for this process is also shown to produce comparable levels of acceleration.

ISSN:0003-6951    

DOI:10.1063/1.94783

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

It is shown that a gain‐guided laser array couples via propagating fields rather than the evanescent mode coupling typically responsible for directional coupling in passive (directional couplers) and active (laser array) devices. We show that these phase‐locked modes exhibit an interference pattern, in the junction plane, which arises from the curvature of the phase fronts of optical fields of the interacting lasers. The experimental results are interpreted with the aid of a simple theoretical model, and the effect of the observed mode pattern on the coupling of gain‐guided lasers is discussed.

ISSN:0003-6951    

DOI:10.1063/1.94784

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

A pulsed acoustic laser probe is used to measure vertical acoustic displacements in the near field of surface defects. A method of optically determining acoustic reflection coefficients in the time domain is presented. The spatial variation of acoustic displacements over a slot is modeled with a static theory. This theory estimates a depth of 230 &mgr;m for a 250‐&mgr;m‐deep slot. A near field image of a fatigue crack demonstrates an application of the technique.

ISSN:0003-6951    

DOI:10.1063/1.94785

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The mutual interaction between intense relativistic electron bunches and a cavity was investigated. It was found that this interaction generated an oscilating voltage in the cavity with an amplitude and a phase that depended on (1) the frequency of the modulated electron beam, (2) the characteristic frequency of the cavity, (3) the characteristic impedance of the cavity, and (4) peak beam current. This voltage caused energy exchange between electrons within a bunch resulting in modifications of the shape and peak current of the bunches. For a ‘‘critical’’ cavity geometry the voltage increased to a high amplitude, drastically reducing beam peak and average currents.

ISSN:0003-6951    

DOI:10.1063/1.94786

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

This letter describes an ion source using a cylindrical microwave cavity operating in a hybrid mode associated with the TE211empty cavity mode. The design principles and associated electrical systems are also discussed. Extracted beam current versus accelerating voltage, and specific energy versus extracted beam current are displayed over the range of flow rates 20–80 sccm and absorbed powers 80–150 W. The results show the feasibility of this concept. The ion source has many potential uses such as space propulsion, material processing, and neutral beam ion sources.

ISSN:0003-6951    

DOI:10.1063/1.94787

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

Absolutely uniform illumination of spherical laser fusion pellets is possible when the energy deposition from a single beam is given by a simple cos2 &thgr; distribution. Conditions can be derived for which the laser beam targeting angles allow this absolute illumination uniformity. Configurations based upon the cube and higher order Platonic solids satisfy the constraints, as well as an infinite class of other less symmetric configurations.

ISSN:0003-6951    

DOI:10.1063/1.94788

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

Electric field induced changes in the x‐ray diffraction pattern of nylon 11 films containing a mixture of the alpha and gamma crystal phases are presented. These changes indicate an orientation of crystallites such that dipoles are aligned in the direction of the poling field. Correlation between this crystal orientation and piezoelectric activity was observed.

ISSN:0003-6951    

DOI:10.1063/1.94789

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The effects of both planar and axial channeling on the profile of 5‐keV boron ions implanted into (100) oriented silicon wafers are demonstrated. A tilt angle of 12° from the (100) axis in a ‘‘random’’ crystallographic direction is required to minimize the (100) axial channeling tail. It is also shown that the effect of channeling along 100 planar channels produces a negligible addition to the channeling tail, whereas channeling along the (110) planar channels produces a measurable contribution. Implantation through a thin, 8‐nm, thermally grown silicon dioxide layer with the ion beam aligned along the (100) direction produces an ion profile comparable to an offset of 9° in a random direction.

ISSN:0003-6951    

DOI:10.1063/1.94790

出版商:AIP    

年代:1984

数据来源: AIP