摘要:

We show that a crystal spectrometer used in the Laue´ mode is a useful diagnostic of high‐energy x‐ray emission from laser fusion plasmas. It has good collection efficiency and adequate energy resolution for continuum measurements. The instrument measures time integrated x‐ray spectra with a resolving powerE/&Dgr;E≊10 for photon energies between 60 and 300 keV. A strong signal and no detectable background are obtained in laser fusion experiments where ∼15 J of x rays are released in a pulsed (1 ns), hard (kT≊200 keV) spectrum. A Lanex/Tri‐X phosphor/film combination is used as a focal plane detector; we report its relative energy calibration. Because of the imperfection of available crystals, detailed measurements of reflectivity along the crystal are required to achieve absolute calibration.

ISSN:0034-6748    

DOI:10.1063/1.1137319

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Diamagnetic measurements of a field‐reversed theta‐pinch plasma are performed with a simplified diagnostic consisting of either a single‐flux loop and several magnetic probes or magnetic probes only. Numerical and experimental evidence of the validity of these techniques is presented.

ISSN:0034-6748    

DOI:10.1063/1.1137320

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Neutral beams are used to fuel and heat the Tandem Mirror Experiment Upgrade (TMX–U) at LLNL. We have studied these beams spectroscopically to determine their species mix (H, H2, H+3) and impurity content (H2O). From the shapes of the spectral lines, we measured the divergences of the various components and compared them with the numerically determined divergence. By measuring the area under the various Doppler‐shifted lines, we determined the species mix and found that the atomic species fraction is lower than expected (30% to 45% rather than 60%). Although there is good agreement between the measured and calculated divergence for the atomic component of the beam, the molecular components have larger divergences, part of which can be accounted for by the dissociation of the molecules.

ISSN:0034-6748    

DOI:10.1063/1.1137321

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

By employing a condenser system charging up at high speed with a triac switch, a stable tokamak discharge with a high repetition rate was achieved. A good reproducibility of the tokamak discharge made detailed measurements of spatial distribution of plasma and wave parameters possible, with a sampling technique. Basic studies on waves and particle transport in a tokamak configuration are possible with this system.

ISSN:0034-6748    

DOI:10.1063/1.1137201

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A dissector/restorer‐type framing camera tube has been characterized with a Nd:YAG mode‐locked laser. The three‐frame format tube, referenced to the photocathode, has a 5×5‐mm field of view and 0.3‐ns duration frames with better than 5 lp/mm spatial resolution. A scan‐rate matching technique is described that can increase the framing speed into the subpicosecond range for this type of camera tube.

ISSN:0034-6748    

DOI:10.1063/1.1137202

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A novel modification to the Blumlein circuit excitation method is presented which allows for automatically timed UV preionization of the main‐glow discharge of a miniature 337‐nm N2TEA laser without the use of time‐delayed circuits commonly used in larger transverse discharge lasers. The laser reliably produces subnanosecond, gain‐switched output pulses of 65 kW at rates up to 50 Hz, with a stability of a few percent, and efficiency of 0.06%.

ISSN:0034-6748    

DOI:10.1063/1.1137203

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

We present a simple and inexpensive TTL variable delay generator with nanosecond time step resolution and subnanosecond jitter. Its application is intended for the synchronization of pulsed multilaser systems to be used in resonant ionization spectroscopy studies.

ISSN:0034-6748    

DOI:10.1063/1.1137204

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

We describe the construction and performance of a low‐cost, easy‐to‐build laser‐beam alignment device (scanner) which allows the simultaneous display of the transversex–yintensity distributions of two parallel or antiparallel beams. The novel feature of this scanner is that it can measure the relative positions of the two beams simultaneously. This makes it an excellent alignment tool for two‐photon experiments. The device is also useful for monitoring the transverse mode quality and for measuring the beam diameter. It serves for beam diameters down to 40 &mgr;.

ISSN:0034-6748    

DOI:10.1063/1.1137205

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A fully synchronous five‐decade ECL counter is described, operable to beyond 75 MHz and producing two distinct TTL‐level outputs separated by presettable N+1 and M+1 input pulses. Intended primarily for laser pulse studies, the counter allows precise Q‐switch–mode‐lock synchronization, yielding greater optical pulse stability than with a‐ or semisynchronous synchronizer designs. In addition, the dual modulo feature allows easy selection of one particular optical pulse in the Q‐switched output train for close study.

ISSN:0034-6748    

DOI:10.1063/1.1137301

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The position and velocity of optically levitated glass spheres (radii 10–20 &mgr;m) moving in a gas are measured accurately, rapidly, and continuously using a high‐speed rotating polygon mirror. The experimental technique developed here has repeatable position accuracies better than 20 &mgr;m. Each measurement takes less than 1 &mgr;s and can be repeated every 100 &mgr;s. The position of the levitated glass spheres can be manipulated accurately by modulating the laser power with an acoustic optic modulator. The technique provides a fast and accurate method to study general particle dynamics in a fluid.

ISSN:0034-6748    

DOI:10.1063/1.1137302

出版商:AIP    

年代:1983

数据来源: AIP