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Showing papers by "Norman S. Kopeika published in 1978"


Journal ArticleDOI
TL;DR: In this paper, a long wave electromagnetic signal detection by glow-discharge plasma, based upon gas breakdown theory by high frequency electric fields, is developed to include internal signal amplification, upper and lower limits to response linearity, temporal and spectral response properties, and noise in the abnormal glow discharge.
Abstract: The mechanism of long wave electromagnetic signal detection by glow-discharge plasma, based upon gas breakdown theory by high frequency electric fields, is developed to include internal signal amplification of the order of that associated with the photomultiplier, upper and lower limits to response linearity, temporal and spectral response properties, and noise in the abnormal glow discharge. Agreement between signal-to-noise expressions in this analysis and measurements involving simple and inexpensive glow discharge indicator lamps exhibiting excellent sensitivity to microwave radiaion is quite good. An inherent ideal limit to speed of response is derived which indicates picosecond-order risetimes are theoretically possible if parasitic reactance effects which limit risetimes of present day devices to microsecond order can be overcome. Sensitivity can be improved further by increasing the number of free electrons. Enhanced diffusion current losses for a subnormal glow yield spectrally flat response which can be useful in radiometric applications.

77 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used large dc bias fields for detecting ultra-violet raidation in gas-filled photodiodes, and showed that the response is non-linear with? varying inversely with wavelength.
Abstract: Photoionization of excited atoms and resonant absorption effects, which can decrease gas breakdown thresholds by high-power lasers at decreasing wavelengths, also improve low intensity detection sensitivities of gas-filled photodiodes when such devices are biased with dc fields close to gas breakdown. Spectral results indicate very promising potential sensitivity for detecting ultra-violet raidation. D* even in the visible is comparible to that of silicon photodiodes. The "relatively" large dc bias fields employed here improve speed of response significantly. Over moderate (10 -7 - 10-8W) received signal powers response is non-linear with ? varying inversely with wavelength.

15 citations


Journal ArticleDOI
TL;DR: The effective cross-section concept, analogous mathematically to Panarella's effective photon concept, is confirmed experimentally and Uniform spatial profiles of excited atom cross sections yield linear response to incident light, unlike previous results with Gaussian spatial profiles.
Abstract: The effective cross-section concept, analogous mathematically to Panarella's effective photon concept, is confirmed experimentally. Uniform spatial profiles of excited atom cross sections yield linear response to incident light, unlike previous results with Gaussian spatial profiles. Implications include potentially improved wavelength tuning sensitivity with the optogalvanic effect, obtaining response linearity in gas discharge detectors of uv and visible light and, because of the analog, modeling the geometrical aspects of Panarella's effective photon concept.

9 citations


Journal ArticleDOI
TL;DR: In this paper, the rise time of a gas-filled photodiode at blue-green wavelengths is found to be less than that at red wavelengths, and it is suggested that these phenomena decrease parasitic inductance of the tube.
Abstract: The rise time of a gas-filled photodiode at blue-green wavelengths is found to be less than that at red wavelengths. As photoionization of excited atoms in such devices increases response to light of decreasing wavelength over that provided by the photocathode, spectral differences in rise time are also attributed to the same mechanism. It is suggested that these phenomena decrease parasitic inductance of the tube. This implies that rise times in glow discharge detectors of EM radiation can be improved through miniaturization of inter-electrode spacing.

7 citations


Journal ArticleDOI
TL;DR: Very high sensitivity with simple inexpensive commercial neon glow lamps designed for indicator-lamp applications is observed at the X band in synchronous detection as mentioned in this paper, which is equivalent to 10/sup -22/ W /spl dot/Hz/spl -1/ with 1-mW localoscillator power.
Abstract: Very high sensitivity with simple inexpensive commercial neon glow lamps designed for indicator-lamp applications is observed at X band in synchronous detection. Typical minimum detectable signals with 10-nW-order local-oscillator powers are 10/sup -17/ W /spl dot/ Hz/sup -1/ or lower. This is equivalent to 10/sup -22/ W /spl dot/Hz/spl -1/ with 1-mW local-oscillator power. As such lamps can be used without damage in high microwave fields, they can be used in principle with appropriate local-oscillator power levels to reach ideal microwave noise equivalent power (NEP) limits. The low NEP and noise figure result from the high responsivities of such devices which are due to high internal signal gain. Experimental results correlate well with the enhanced-ionization collision-rate detection model.

5 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that X-rays can affect population inversion detrimentally in TEA lasers, and that the effect of X-ray preionization on TEA laser was investigated.
Abstract: Illumination of gases by X-rays results in decreasing populations of excited states for increasing X-ray dosage. This deexcitation effect decreases for increasing dc bias fields. These results indicate that X-rays can affect population inversion detrimentally. Implications concerning X-ray preionization in TEA lasers are discussed.

5 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the X-band directionality of response by sensitive d.c. glow-discharge detectors of microwave radiation and found no noticeable dependence on the D.C. field being parallel or perpendicular to the microwave field, thus supporting a previously developed modol of detection by the plasma.
Abstract: Investigations of X-band directionality of response by sensitive d.c. glow-discharge detectors of microwave radiation indicate no noticeable dependence on the d.c. field being parallel or perpendicular to the microwave field, thus supporting a previously developed modol of detection by the plasma. However, if the microwave frequency is such that the electrode dimension tangential to the microwave field approaches one-half the wavelength, changes in response directionality occur which appear to result possibly from diffraction and scattering by the glass envelope, resulting in mode conversion and transmission line resonance by the electrodes. Lack of noticeable antenna properties by these devices at X-band suggests the detection mechanism is based primarily in the discharge itself and that ‘ probe ’ rectification by the anode, though not excluded completely, is not too significant at X-band (⋍ 3 cm wavelength) in view of the small inter-electrode space ( 1–2 mm) of such devices. Inter-electrode distances ...

5 citations


Journal ArticleDOI
TL;DR: The effection cross section concept for low intensity light illumination of gas discharges is shown to be analogous to high intensity breakdown of gases as interpreted by Panarella's "effective photon" concept as discussed by the authors.
Abstract: The effection cross section concept for low intensity light illumination of gas discharges is shown to be analogous to high intensity breakdown of gases as interpreted by Panarella's "effective photon" concept. This mathematical result is suggested as a possible interpretation of strikingly similar nonlinearities of gas breakdown by light measured in both cases at their respectively different intensity levels.

3 citations


Journal ArticleDOI
01 Aug 1978
TL;DR: In this paper, a relatively intensive electrooptics curriculum is described, including in particular source material, which allows undergraduate electrical engineering students who wish to do so to specialize in electro-optics.
Abstract: A relatively intensive electrooptics curriculum is described in detail, including in particular source material. This curriculum allows undergraduate electrical engineering students who wish to do so to specialize in electrooptics. Constraints somewhat unique to Israel are described, as well as an evaluation of the curriculum based on feedback from graduating students. The academic level is such that over 50 percent of the undergraduate senior projects connected with electrooptics have been published in the international scientific and engineering journals.

1 citations