摘要:

A high pressure, radio frequency discharge nozzle beam source has been developed for the production of very intense (⩾1018atoms sr−1  s−1) supersonic beams of oxygen atoms. An efficient impedance matching scheme has been devised for coupling the radio frequency power to oxygen–rare gas mixtures as a function of gas pressure, temperature, and composition. Techniques for localizing the discharge directly behind the orifice of a specially designed quartz nozzle have also been developed. The above combine to yield a beam source which reliably produces a high degree of molecular dissociation in oxygen–rare gas mixtures at pressures up to 350 Torr. Atomic oxygen mean translational energies from 0.14–0.50 eV have been achieved using the seeded beams technique with Mach numbers up to 10 being realized. When helium is used as the carrier gas both O(3PJ) and O(1D2) atoms are present in the beam, while only ground state atoms appear to be present in argon seeded mixtures. This paper describes the design, construction, and operation of this beam source and provides a characterization of the atomic oxygen beams it has reproducibly generated in our laboratory.

ISSN:0034-6748    

DOI:10.1063/1.1136170

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

An impact facility has been designed and constructed to produce and measure large amplitude one‐dimensional compression and shear waves in solids. Design considerations and experimental details to produce the necessary impact configuration and to measure the particle velocity profiles resulting from compression and shear waves are described. Experimental results are presented to show that the impact facility was satisfactorily constructed. After a brief discussion of shear wave measurements, the experimental measurements made under compression and shear loading in polymethyl methacrylate and polycrystalline aluminum oxide are presented. These results are expected to provide new information on material response at high strain rates.

ISSN:0034-6748    

DOI:10.1063/1.1136171

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A reactor suitable for kinetic measurements on photolytically initiated elementary free‐radical reactions over approximately the 300–1900 K temperature range is described. Performance data are given for the O+CH4→OH+CH3reaction.

ISSN:0034-6748    

DOI:10.1063/1.1136172

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Using the pulsation properties of gas bubbles it is possible to measure acoustically volumes c.q. equivalent diameters of gas bubbles in the range of 1.8–2.1 mm, produced at low frequencies at capillary tubes in a silent environment. Hence it is possible to measure very low gas flow rates (from 4 up to 100 mm3/s). During formation of bubbles at capillary tubes phenomena of repeated coalescence can occur between a just released bubble and the following bubbles under formation. This occurrence depends on the speed of rise, the bubble volume and the formation frequency. There is experimental evidence that this swallowing‐up gives cause to a swinging‐up of the amplitude of the pulsation signal. This coalescence process is the main physical limitation of the claimed method to low frequencies. There is also some experimental evidence by laser pulse synchronization between acoustics and bubble photographs that the often reported neck during bubble formation actually is an effect caused by this swallowing‐up process.

ISSN:0034-6748    

DOI:10.1063/1.1136173

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A diagnostic system based on the heavy ion beam probe technique has been developed for the Elmo Bumpy Torus. A variety of singly charged alkali metal ions have been used in the probing beam; detection of multiply charged reaction products allows a continuous spatially resolved monitor of the plasma space potential. Typical spatial resolution is 1 cm−3; time resolution is on the order of 1 s. The potential measurement is direct and properly referenced to the plasma ground. An investigation into possible sources of error in the measurement points to the conclusion that the uncertainty is an order of magnitude less than the experimentally measured potentials.

ISSN:0034-6748    

DOI:10.1063/1.1136174

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The power‐per‐line analyzer is an instrument designed to provide a continuous real‐time display of any laser spectra on an oscilloscope. In this article the HF and DF laser version of this instrument is described. A new continuous drive and electronic calibration method are used, eliminating the need for mechanical and optical recalibration. The wavelength is proportional to the dc voltage generated by the scanner’s angular position transducer, which drives thexaxis of an oscilloscope. The relative line intensity is proportional to the dc voltage generated by a pyroelectric detector and drives theyaxis of the oscilloscope. The wavelength calibration accuracy of the final instrument is 0.8% full scale, and the resolution is 2 nm.

ISSN:0034-6748    

DOI:10.1063/1.1136175

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A 1.8 cm3active volume gas‐recirculating mini‐TEA CO2laser of relatively simple design is described. The laser is capable of operating at 500 Hz with an average output of 10 W. The device is line tunable over ∼50 CO2laser frequencies, has operated with up to 34 J/l output density and has a nearly diffraction‐limited output.

ISSN:0034-6748    

DOI:10.1063/1.1136176

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

An isothermally jacketed liquid calorimeter permitting thermochemical studies on spontaneous combustion in fluorine has been built and tested. The fluorine storage tank was located outside the calorimeter vessel, thus lowering the heat capacity of the system and its thermal inertia. Particular attention was paid to the method and rate of liquid circulation since it largely determines the experimental accuracy. The system can be calibrated electrically. The possible experimental errors are discussed, and their analysis shows that calibration is feasible with an accuracy of ≳99.98%. A series of measurements involving a temperature rise of about 0.9 K showed a standard deviation of 0.02%.

ISSN:0034-6748    

DOI:10.1063/1.1136177

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

A pulse generator for NMR application is described. Eighteen output channels are provided to allow use in both single and double resonance experiments. Complex pulse sequences may be generated by loading instructions into a 256‐word by 16‐bit program memory. Features of the pulse generator include programmable time delays from 0.5 &mgr;s to 1000 s, branching and looping instructions, and the ability to be loaded and operated either manually or from a PDP‐11/10 computer.

ISSN:0034-6748    

DOI:10.1063/1.1136178

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

An automated system for measuring the pyroelectric properties of materials is described. This system can simultaneously measure pyroelectric coefficients and permittivities eliminating errors introduced in the figures of merit by temperature uncertainties. Results on deuterated triglycine fluoroberyllate (DTGFB) are presented.

ISSN:0034-6748    

DOI:10.1063/1.1136179

出版商:AIP    

年代:1980

数据来源: AIP