- Email: [email protected]
Atmospheric ozone profiles from high resolution uv spectra obtained with a balloon-borne spectrometer
Classified abstracts
5639-5548
33 5639. Mod+locking by l intraavity plasma. Part II. Experimmtal results. (ca=w The results of an experimental investigation of TEA-CO2 laser modclocking by an intracavity plasma are described in this paper. The observations evidence the critical role played by the plasma switching process; complete mode-locking was consecutive to a fast cutoff of the gain-switched laser pulse. The laser beam was focused by the plasma at the instant of gas breakdown. The short pulse trains were depolarized, even though the gain-switched pulse producing the plasma was plane polarized. The plasma was shown to both reflect and transmit laser light by moving its relative position in the laser cavity. The results are discussed in terms of a model involving the combination of an amplitude shutter and a frequency shifter. We establish the relationship between our experiment and similat ones reported in the literature. M PleY and P A Bchnger, Can J Phys, 60 (l), 1982,77-87. 33 5640. Varlatlons in electrumtramport in 8rgon witk temperature near tke Ramaauer-Tow4 ml&mm. (GB) A previously developed three-term expansion method has been extended to study the electron swarm in argon in the energy range of the Ramsauer-Townsend minimum. The swarm parameters of electrons have been computed at temperatures of 89.6, 293 and loo0 K in the range 1 x 10-‘lSE/N (VcmQ 1 x lo- ” . In particular, the dependence of the drift velocity on gas temperature in the vicinity of the minimum is discussed in detail, and it is shown that a ‘crossing curve’ property appears. Also the validity of the conventional two-term approximation is confirmed by direct comparison with the lth-order distribution function (l=O, 1,2) in the region of the minimum. (Japan) T Makabe and T Mori, J Phys D: Appl Phys, 15 (a), 1982, 1395-1402. 33 5641. Effect of bias on mppiap probes aad bolometers for tokamak edge diagnonit~(GB) Analysis is presented for the particle and energy flow to an electrically biasable probe immersed in the magnetic field of the boundary plasma of a tokamak or other magnetic confinement device. The analysis is appropriate to the operation of the probe in the voltagccurrent (Langmuir) probe mode, the thermal power (bolomcter) mode, hydrogenic ion trapping mode or impurity deposition mode. The formulation of the analysis permits the use of any cross-field diffusion model, i.e. classical, semi-classical, empirical. The principal conclusion of the analysis is that a probe should be operated simultaneously in at least two modes, eg. Langmuir and bolometer modes. In this way it is possible to measure plasma density and electron and ion temperatures separately with several consistancy checks also available. Under some circumstances it is also possible to measure the hydrogenic cross-field diffusion coefficient and impurity ion density, temperature and charge state. It is necessary to operate a bolometer in a biased mode in order to infer heat loads to nonfloating surfaces, e.g. limiters and divertor targets, since heat flux is a strong function of the potential difierence between the plasma and surface. P C Stangeby, J Phys D: Appl Phys, IS (6). 1982, 1007-1029. 33 5641, Study of tbe cbamct~cs of tkermhic ionization detectors. (USA) Measurements of gain and noise in a thermionic detector (with an electrostatically shielded region) using Rb and K vapour are described. An approximate theory for spacecharge limited operation is developed and found to agree with observations. Improvement in diode design are suggested. @anada) D C Tkompaon and B P Stoicbeff, Reu Sci Instrum, 53 (6), 1982,822-828. 33 5643. Development of lngle-partick detectors for keV iom. (USA) A series of three single-particle detectors for the detection of ions with keV energies has been built and investigated by experiment and by computer simulation. The incident ions hit a converter electrode and produce secondary electrons which are accelerated onto the funnel of a channel electron multiplier (CEM). Experimental information was obtained for secondary electron yields, y. of slow multiply charged ions and the influence of y on the detector efficiency E is discussed. Efficiencies E near unity have been achieved for ions incident on an effective area of more than 20 mm dia. E is greater than 90% for all ions and for count rates up to 3 x 10. s-l. The performance at higher count rates can probably be improved with a CEM of lower resistance. Klaus Rina et al, Reu Sci Inmum, 53 (6), 1982.829-937.
34. ELECTRONICS TECHNOLOGY
AND
HIGH
ALTITUDE
PHYSICS
AND
34 5644.Atmoqbhcoameprofikshmkigbreaolutionmspectraobtained with 8 brhowborne spectrawter. (USA) High resolution solar spectra at high and low sun angles in the 32003400-A region were obtained during balloon flights on 9 February 1977 (altitude 41 km) and 17 February 1977 (altitude 29 km). These data were analysed using a layer-by-layer three-wavelength dilTerential absorption method. Ozone volume-mixing ratio profiles, which agree with standard profiles, were derived. Suggestions are made for improving the accuracy of the results in future measurements. J R Glllls et al, Appl Optic, 21 (3). 1982.413-420. 34 5615. Temporal lml lngtdar spwiimg of blueqeea pulses in cluuds. (USA) The first blucgreen laser propagation measurements through clouds that simulate the geometry of a satellite-to-ground communication link were made. The time history of large diameter (-6&m) pulses illuminating cloud tops was recorded as a function of receiver lield of view (FOV). The maximum pulse stretching observed for nanosecond laser pulses was 20 psec for clouds of 1.5&m thickness. It was shown that the pulses could in general be represented by a linear combination of two modified y functions: One, a slowly decaying term, represents the power from the diffusion type of multiple scattering. The other, a much faster decaying term, represents the power from a direct nonscattered portion of the beam or from a lower order of multiple scattering. For very dense clouds, the only component measured was the diffusion type. Data of FOV scans are presented for various values of optical thickness. G C Mooradlaa and M Celler, Appl Optics, 21 (9), 1982, 1572-1577. 34 5646. Amnqberk OYDIW detexmirmtionby solar ocadmtion using tke uv spccaometer on tbe Solar Maximum Missh (USA) The uv spectrometer polarimeter instrument on the Solar Maximum Mission spacecraft has been used to measure ozone in the 53-75-km altitude interval by the technique of solar occultation. A 1 x 180-s of arc entrance aperture spectrometer with 0.04-A spectral resolution was employed. Resulting highquality data are reduced by expressing measured uv attenuation as a Volterra integral equation. Solution of the equation is accomplished by expressing the integral in terms of a series representing the sum of ozone densities contained in concentric shells through tangent points separated by specified altitude increments. Sample ozone vs altitude profiles are presented for the equatorial region. These data show reproducibility to better than 10%. The density at 60 km is 7.3 kO.15 x lo9 cme3 for 2.5” latitude and longitudes between 81 and 105” west in September 1980. Density vs altitude profile exhibits changes in slope between SOand 75 km. A C Aiiia et al, Appl Optics, 21 (13), 1982, 2421-2424. 34 5647. Laser beam power fade induced by system aod atmospheric effects. WA) A simple model for the propagation of laser beams in a turbulent atmosphere is presented. Closed analytical expressions, suitable for system research and real-time analysis of field experiments, are obtained for the probability of the intercepted power to exceed a certain threshold level. A hierarchy of approximations is described and the validity range of each is discussed. (Israel) U Halavee et al, Appl Optics, 21 (13), 1982, 2432-2436. 34 wts of angular scattering 8nd inteaslty 5648. Slltaneous aelatlllatioo la tke ammap&e. (USA) Simultaneous measurements of the spatial covariancc of intensity and the angular spectrum of plane waves have been made for a diverging HtNe laser beam propagating over a 1 km horizontal path. Most of the data are taken during strong scintillation. The measured angular spectrum is used to estimate the wave-structure function D(s). The propagation equation for the intensity covariance depends on the medium only through the longitudinal derivative of D(s). Thus, for a homogeneous medium, D(s) is sufficient to calculate the intensity covariancc. although such a calculation has not been done in general. The estimated D(s) is used to calculate the intensity covariance by using weak scintillation theory and also by using an asymptotic theory for strong scintillation. The measured intensity ~~ariances are then compared with these calculations. In both cases there is qualitative agreement, but the quantitative comparison is poor. It is 419
5639-5548
33 5639. Mod+locking by l intraavity plasma. Part II. Experimmtal results. (ca=w The results of an experimental investigation of TEA-CO2 laser modclocking by an intracavity plasma are described in this paper. The observations evidence the critical role played by the plasma switching process; complete mode-locking was consecutive to a fast cutoff of the gain-switched laser pulse. The laser beam was focused by the plasma at the instant of gas breakdown. The short pulse trains were depolarized, even though the gain-switched pulse producing the plasma was plane polarized. The plasma was shown to both reflect and transmit laser light by moving its relative position in the laser cavity. The results are discussed in terms of a model involving the combination of an amplitude shutter and a frequency shifter. We establish the relationship between our experiment and similat ones reported in the literature. M PleY and P A Bchnger, Can J Phys, 60 (l), 1982,77-87. 33 5640. Varlatlons in electrumtramport in 8rgon witk temperature near tke Ramaauer-Tow4 ml&mm. (GB) A previously developed three-term expansion method has been extended to study the electron swarm in argon in the energy range of the Ramsauer-Townsend minimum. The swarm parameters of electrons have been computed at temperatures of 89.6, 293 and loo0 K in the range 1 x 10-‘lSE/N (VcmQ 1 x lo- ” . In particular, the dependence of the drift velocity on gas temperature in the vicinity of the minimum is discussed in detail, and it is shown that a ‘crossing curve’ property appears. Also the validity of the conventional two-term approximation is confirmed by direct comparison with the lth-order distribution function (l=O, 1,2) in the region of the minimum. (Japan) T Makabe and T Mori, J Phys D: Appl Phys, 15 (a), 1982, 1395-1402. 33 5641. Effect of bias on mppiap probes aad bolometers for tokamak edge diagnonit~(GB) Analysis is presented for the particle and energy flow to an electrically biasable probe immersed in the magnetic field of the boundary plasma of a tokamak or other magnetic confinement device. The analysis is appropriate to the operation of the probe in the voltagccurrent (Langmuir) probe mode, the thermal power (bolomcter) mode, hydrogenic ion trapping mode or impurity deposition mode. The formulation of the analysis permits the use of any cross-field diffusion model, i.e. classical, semi-classical, empirical. The principal conclusion of the analysis is that a probe should be operated simultaneously in at least two modes, eg. Langmuir and bolometer modes. In this way it is possible to measure plasma density and electron and ion temperatures separately with several consistancy checks also available. Under some circumstances it is also possible to measure the hydrogenic cross-field diffusion coefficient and impurity ion density, temperature and charge state. It is necessary to operate a bolometer in a biased mode in order to infer heat loads to nonfloating surfaces, e.g. limiters and divertor targets, since heat flux is a strong function of the potential difierence between the plasma and surface. P C Stangeby, J Phys D: Appl Phys, IS (6). 1982, 1007-1029. 33 5641, Study of tbe cbamct~cs of tkermhic ionization detectors. (USA) Measurements of gain and noise in a thermionic detector (with an electrostatically shielded region) using Rb and K vapour are described. An approximate theory for spacecharge limited operation is developed and found to agree with observations. Improvement in diode design are suggested. @anada) D C Tkompaon and B P Stoicbeff, Reu Sci Instrum, 53 (6), 1982,822-828. 33 5643. Development of lngle-partick detectors for keV iom. (USA) A series of three single-particle detectors for the detection of ions with keV energies has been built and investigated by experiment and by computer simulation. The incident ions hit a converter electrode and produce secondary electrons which are accelerated onto the funnel of a channel electron multiplier (CEM). Experimental information was obtained for secondary electron yields, y. of slow multiply charged ions and the influence of y on the detector efficiency E is discussed. Efficiencies E near unity have been achieved for ions incident on an effective area of more than 20 mm dia. E is greater than 90% for all ions and for count rates up to 3 x 10. s-l. The performance at higher count rates can probably be improved with a CEM of lower resistance. Klaus Rina et al, Reu Sci Inmum, 53 (6), 1982.829-937.
34. ELECTRONICS TECHNOLOGY
AND
HIGH
ALTITUDE
PHYSICS
AND
34 5644.Atmoqbhcoameprofikshmkigbreaolutionmspectraobtained with 8 brhowborne spectrawter. (USA) High resolution solar spectra at high and low sun angles in the 32003400-A region were obtained during balloon flights on 9 February 1977 (altitude 41 km) and 17 February 1977 (altitude 29 km). These data were analysed using a layer-by-layer three-wavelength dilTerential absorption method. Ozone volume-mixing ratio profiles, which agree with standard profiles, were derived. Suggestions are made for improving the accuracy of the results in future measurements. J R Glllls et al, Appl Optic, 21 (3). 1982.413-420. 34 5615. Temporal lml lngtdar spwiimg of blueqeea pulses in cluuds. (USA) The first blucgreen laser propagation measurements through clouds that simulate the geometry of a satellite-to-ground communication link were made. The time history of large diameter (-6&m) pulses illuminating cloud tops was recorded as a function of receiver lield of view (FOV). The maximum pulse stretching observed for nanosecond laser pulses was 20 psec for clouds of 1.5&m thickness. It was shown that the pulses could in general be represented by a linear combination of two modified y functions: One, a slowly decaying term, represents the power from the diffusion type of multiple scattering. The other, a much faster decaying term, represents the power from a direct nonscattered portion of the beam or from a lower order of multiple scattering. For very dense clouds, the only component measured was the diffusion type. Data of FOV scans are presented for various values of optical thickness. G C Mooradlaa and M Celler, Appl Optics, 21 (9), 1982, 1572-1577. 34 5646. Amnqberk OYDIW detexmirmtionby solar ocadmtion using tke uv spccaometer on tbe Solar Maximum Missh (USA) The uv spectrometer polarimeter instrument on the Solar Maximum Mission spacecraft has been used to measure ozone in the 53-75-km altitude interval by the technique of solar occultation. A 1 x 180-s of arc entrance aperture spectrometer with 0.04-A spectral resolution was employed. Resulting highquality data are reduced by expressing measured uv attenuation as a Volterra integral equation. Solution of the equation is accomplished by expressing the integral in terms of a series representing the sum of ozone densities contained in concentric shells through tangent points separated by specified altitude increments. Sample ozone vs altitude profiles are presented for the equatorial region. These data show reproducibility to better than 10%. The density at 60 km is 7.3 kO.15 x lo9 cme3 for 2.5” latitude and longitudes between 81 and 105” west in September 1980. Density vs altitude profile exhibits changes in slope between SOand 75 km. A C Aiiia et al, Appl Optics, 21 (13), 1982, 2421-2424. 34 5647. Laser beam power fade induced by system aod atmospheric effects. WA) A simple model for the propagation of laser beams in a turbulent atmosphere is presented. Closed analytical expressions, suitable for system research and real-time analysis of field experiments, are obtained for the probability of the intercepted power to exceed a certain threshold level. A hierarchy of approximations is described and the validity range of each is discussed. (Israel) U Halavee et al, Appl Optics, 21 (13), 1982, 2432-2436. 34 wts of angular scattering 8nd inteaslty 5648. Slltaneous aelatlllatioo la tke ammap&e. (USA) Simultaneous measurements of the spatial covariancc of intensity and the angular spectrum of plane waves have been made for a diverging HtNe laser beam propagating over a 1 km horizontal path. Most of the data are taken during strong scintillation. The measured angular spectrum is used to estimate the wave-structure function D(s). The propagation equation for the intensity covariance depends on the medium only through the longitudinal derivative of D(s). Thus, for a homogeneous medium, D(s) is sufficient to calculate the intensity covariancc. although such a calculation has not been done in general. The estimated D(s) is used to calculate the intensity covariance by using weak scintillation theory and also by using an asymptotic theory for strong scintillation. The measured intensity ~~ariances are then compared with these calculations. In both cases there is qualitative agreement, but the quantitative comparison is poor. It is 419