摘要:

A 15×15 cm cross section, 50 cm long, TEA CO2amplifier using a reliable and simple discharge system is described. This system permits external control of the width of the discharge and is easily scalable. The spatial distribution of the small signal gain over the cross section of the amplifier is investigated. An average small signal gain coefficient of 0.022 cm−1is obtained at an input energy density of 100 J/liter. Measurement of the saturated energy gain is reported. The small signal gain has also been measured on a smaller cross section but more heavily excited amplifier, using a similar discharge system.

ISSN:0034-6748    

DOI:10.1063/1.1134343

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

The output of an optical free induction decay pulse generator was amplified up to the 0.1 J level. A pulse width of 500 psec was resolved on a Tektronix 519 oscilloscope using a pyroelectric detector. This agreed well with a linear computer model of the system response.

ISSN:0034-6748    

DOI:10.1063/1.1134344

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A differential refraction spectrometer for measuring the absolute intensity distribution of microwave spectra in gases by means of dispersion pressure profiles is described. The instrument was applied to study the 60 GHz band spectrum of oxygen under simulated atmospheric conditions (10−3–103Torr, 252–325 K). The detection sensitivity for dispersion was better than 1 part in 109using two high‐Q(∼4×105) resonators at 2:1 related frequencies and a sampling phase meter. Illustrative examples of data taken around 61 GHz, their reduction to spectroscopic parameters, and problems related to dynamic limitations are dealt with.

ISSN:0034-6748    

DOI:10.1063/1.1134345

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A system employing medium energy electrons (1–15 keV) for scanning microscopy and diffraction intensity measurements has been constructed. The specimen is situated in an UHV environment and can be cleaned by argon ion sputtering and heated up to 1000 °C. The resolution is currently about 300 A˚ for scanning images formed when secondary electrons are detected. The use of diffracted beams to form images is shown to provide new types of information regarding the structure and defects of crystal surfaces. Intensities and intensity profiles of diffracted beams can be measured for comparison with theoretical data and structure analysis.

ISSN:0034-6748    

DOI:10.1063/1.1134346

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

By the introduction of a rotating mirror near the exit slit of a Rowland circle mounting, we have designed a rapid scanning spectrometer capable of being synchronized with a short duration source of radiation. The wavelength range 1150–2000 A˚ is covered in 345 A˚ increments by setting the entrance arm at each of several predetermined angles of incidence. Spectral measurements of the vacuum ultraviolet (vuv) carbon monoxide fourth positive system are presented. The spectra have been obtained at a scan speed of 300 A˚/msec, and the conversion from a time scale to a wavelength scale is shown to be linear.

ISSN:0034-6748    

DOI:10.1063/1.1134347

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A new technique for processing laser Doppler velocimeter signals by sampling spectrum analysis is presented. A swept‐filter spectrum analyzer and pulse‐shaping and sample‐and‐hold circuits are employed. Sampling turbulence frequencies up to 4 kHz. In contrast to most tracking techniques, high dropout of signal cases and high frequency signals normally associated with directionally sensitive velocimeter systems can be processed.

ISSN:0034-6748    

DOI:10.1063/1.1134348

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A stereologic method for measuring any moment of an irregular plane section is described.

ISSN:0034-6748    

DOI:10.1063/1.1134349

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A machine capable of fatigue testing high strength alloys at an ultrasonic frequency (20 kHz), and a range of temperatures likely to be encountered by such materials in aerospace and power generation applications and in basic research, is described. The machine is assembled entirely from commercially available components used in ultrasonic joining processes. Basically, it consists of a power supply module and heavy duty transducer capable of delivering up to 1.2 kW of acoustic energy at peak‐to‐peak amplitudes ranging from 10 to 20 &mgr;, which is further amplified by tuned acoustic horns. The machine sets up a 20 kHz standing wave in the resonant test specimen. Peak‐to‐peak displacement amplitudes in the specimen of up to 300 &mgr; (typical stress levels up to 1400 MN/m2) can be achieved. Provisions have also been made to accurately monitor the frequency of testing and the displacement amplitude during the test. As an example of the capabilities of the machine, results of high‐frequency fatigue tests performed over a range of temperatures are presented. Lastly, it is indicated that ultrasonic fatigue testing, by virtue of its extremely high rate of testing, can be conveniently used for the study of very slow fatigue crack propagation in engineering alloys.

ISSN:0034-6748    

DOI:10.1063/1.1134350

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A system is described which can measure plasma electric fields on nanosecond time and submillimeter distance scales. The measurement is made by observing the time dependent deflection of a 10−7A beam of 22 keV He+ions. The measurement does not perturb the plasma.

ISSN:0034-6748    

DOI:10.1063/1.1134351

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A time‐of‐flight technique for the measurement of the energy spectra of electrons ejected in ion–atom collisions is described. Ionization is produced by a pulsed beam of protons which are obtained by chopping the dc proton beam from a Van de Graaff accelerator with a 3.33 MHz high voltage oscillator. Electron energy and angular distributions are derived from time‐of‐flight spectra recorded for different emission angles. This system is capable of measurements for proton energies from 0.25 to 2.0 MeV, ejected electron energies from 0.3 eV to several hundred eV, and electron ejection angles from 30° to 150°. The advantages and limitations of this technique are illustrated.

ISSN:0034-6748    

DOI:10.1063/1.1134352

出版商:AIP    

年代:1975

数据来源: AIP