摘要:

IMPATT diodes are presented as an alternate rf source for EPR. Their noise‐performance is shown to be comparable to klystrons while having the advantages of low cost, long life, and simple power supply requirements. The stability of the IMPATT diode is such that frequency locking is not usually necessary. Where needed, locking may be done with existing klystron lock boxes through the addition of a varactor. An IMPATT marginal oscillator with a sensitivity of about 2 × 1012spins/G is also described. The oscillator's sensitivity is essentially independent of power and it can be used with an external detector or in the self‐detection mode.

ISSN:0034-6748    

DOI:10.1063/1.1686188

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The response characteristics of high sensitivity piezoelectric pressure transducers suitable for use in the plasma flow induced by megawatt‐level electric discharges in low density (<1 Torr) gases are described. The uniquely designed probe records the initial impingement of a large magnitude total pressure pulse (104N/m2with 30&mgr;sec duration), followed by the flow of primary interest with order‐of‐magnitude smaller signals (103N/m2for 400 &mgr;sec). Effects relating to probe and support accelerations, blast shielding and probe heating are evaluated and accounted for in a probe system with a sensitivity of 40 V/atm.

ISSN:0034-6748    

DOI:10.1063/1.1686189

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The atom probe field ion microscope allows single atom identification by combining a field ion microscope with a time‐of‐flight mass spectrometer. A circuit is described which provides time resolution of ±10 nsec in an interval of 100 &mgr;sec for up to eight particles arriving at the detector in any one field evaporation pulse cycle. The duty cycle of the instrument is limited only by the data recording system. The ±10 nsec resolution allows identification of species separated by one mass unit under the worst case conditions of high atomic weight and high accelerating voltage.

ISSN:0034-6748    

DOI:10.1063/1.1686190

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Sulfur films up to 20 &mgr; in thickness have been vacuum deposited on 0.025 mm beryllium foil for use as x‐ray filters. The films are more adherent and uniform than chemically deposited films, and much simpler to prepare than the sulfur‐polystyrene sandwiches described previously. Substrate cooling is required to obtain uniform, reproducible fine‐grained films. An apparatus is described that provides a simple means of cooling substrates and also minimizing sulfur contamination of the vacuum pump.

ISSN:0034-6748    

DOI:10.1063/1.1686191

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A film system for flash x‐ray diffraction studies of shock‐compressed samples is described. This system consists of three elements: A blast cassette; a film assembly; and a small shock‐wave generator. The blast cassette contains baffles, slits, and plastic x‐ray windows to prevent shrapnel penetration of the film holder and destruction of the film. High‐speed film is used in conjunction with a ZnS fluorescent screen. Shock pressures of 85–340 kilobars can be generated in typical samples by a miniature explosive lens and booster weighing about 100 g. Tailoring of the sample pressure is achieved through the selection of the base plate and explosive material. We have used this system to obtain diffraction data in the two‐theta range of 15°−50° using Cu and Mo x‐radiation.

ISSN:0034-6748    

DOI:10.1063/1.1686192

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A small, transverse flow, moderate power cw hydrogen fluoride chemical laser is described. This laser provides up to 10 W of cw output power on a number ofPv(J)lines associated with 3→2, 2→1, and 1→0 vibrational transitions of hydrogen fluoride (HF). Single line power levels of up to 1.5 W were obtained on the strongest HF transitions. The measured electrical efficiency was [inverted lazy s] 1% for a total mass flow of 100 mg/sec. The gain and spectral power distributions were found to be characteristic of a complete inversion rather than a partial zero field inversion on the 2→1 transitions.

ISSN:0034-6748    

DOI:10.1063/1.1686193

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

An apparatus for the study of secondary positive and negative ions from metal surfaces under positive ion bombardment has been constructed in stainless steel using ultra‐high vacuum technology. It provides for triple mass analysis (i.e., of primary and both secondary beams), and energy analysis of the secondary ions. A retarding technique suitable for wide energy distributions has been developed. Some preliminary results obtained are given.

ISSN:0034-6748    

DOI:10.1063/1.1686194

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The configurations and operation of a field spectroradiometer (Exotech model 20‐B spectroradiometer) that measures the intensity of incident and reflected radiation from 0.37 to 2.52 &mgr; and emitted radiation from 2.76 to 13.88 &mgr; are described. The instrument was built by Exotech Inc. from specifications and plans developed by the USDA. Exotech contributed many engineering concepts basedupon knowledge of thetheory involved. The instrument consists of two systems, each made up of an optical unit and a control unit. One system covers the spectral range 0.37–2.52 &mgr;; the other system covers the spectral range 2.76–13.88 &mgr;. The optical units of the two systems mount side‐by‐side on a tiltable base mounted on an aerial lift truck. Separation between the objective lenses is about 30 cm to minimize parallax. The systems may be operated separately or in the tandem, boresighted mode. The control units are mounted in a camper‐type equipment van and are connected to the optical units by 60 m of armored cable. Preamplifiers and auxiliary electronics in the optical units are designed to operate without picking up interferences over this length of cable. The entire system is designed to operate in an outdoor environment. Provision has also been made for photographic annotation of field data setups.

ISSN:0034-6748    

DOI:10.1063/1.1686195

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A linear gate is presented for gating output pulses from a photomultiplier. Measurements with an EMI 9558A tube show the circuit to have a very high cutoff efficiency, turn‐on/off times of about 5 nsec, and very small noise transients.

ISSN:0034-6748    

DOI:10.1063/1.1686196

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

A steady state, dc discharge, electrostatically focused ion beam source with permanent magnet multipole confinement is described. The ion beam is low density,nb[inverted lazy s] 108cm−3, low divergence, &thgr; [inverted lazy s] 1°, energetic,Vb≤5kV, and is suitable for investigating ion beam‐plasma interactions. Ion beam speed and species are determined either by modulating the beam and analyzing the resulting free‐streaming perturbations or by a pulse and time‐of‐flight technique. The amplitude of the free‐streaming signal is enhanced in the electron cyclotron harmonic passbands due to the decreased dielectric function of the background plasma. Two beam‐plasma instabilities, the electron cyclotron drift instability, and an instability at the lower hybrid frequency are observed using this ion source.

ISSN:0034-6748    

DOI:10.1063/1.1686197

出版商:AIP    

年代:1973

数据来源: AIP