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Viscoelastic flow past an infinite plate with suction and constant heat flux
Vacuum~volume35/number 6/pages 223 to 242/1985
Pergamon Press Ltd
Prtnted in Great Britain
Classified abstracts 5706-5894 Classified abstracts 5 7 0 6 - 5 7 1 3 on this page
Compiled by H K h e y r a n d i s h ,
University of Salford
Editor's N o t e The label immediately following the title of each item denotes country of origin of publication, and that at the end of each abstract indicates country of origin of work (where known)
I. G e n e r a l v a c u u m science and e n g i n e e r i n g 10. K I N E T I C T H E O R Y O F GASES 10 5706. Viscoelastic flow past an infinite plate with suction and constant heat flux. (GB) While studying the viscoelastic flow past an infinite plate with suction and constant heat flux between fluid and plate with suction and constant heat flux between fluid and plate, Raptis and Tzivanidis gave the solution of a pair of equations for velocity and temperature as functions of distance. They then gave some approximate solutions. This letter shows that the approximation are not justified and presents an exact analytical study. (India) A K Sanyal and D Ray, J Phys D: Appl Phys, 16 (2), 1983, 17 22. 10 5707. A system for phase and intermittency measurements in periodically turbulent flows. (GB) A measuring system is described which maps the spatial and temporal positions of the periodic turbulent bursts which appear in the boundary layer growing on a surface immersed in an oscillatory travelling-wave type of flow. The basic principle of the system is that whereby a "window" of controllable duration and phase relative to the oscillatory flow is opened and the flow is observed during this opening to examine whether it is laminar or turbulent. The system uses both analogue signal-processing components and digital circuitry under the control of a programmable desk calculator. Some typical results are presented for the growth of tmbulent patches in the boundary layer on a flat plate mounted in one of the Q M C gust tunnels. G Siderides and L Bernstein, J Phys E: Sci hlstrum, 16 (2), 1983, 136 141.
11. GASES A N D SOLIDS 11 5708. An analytical approach for calculating vacuum properties of outgassing tubing systems. (GB) A method has been investigated to calculate vacuum properties, such as flow conductance and pressure drop, for complex tubing systems, taking into account the outgassing of the tube walls. The procedure is based on the determination of the pressure drop, Apl, of each tube element, starting at the chamber with a given mass flow rate. qh~-The flow conductance, G, of the system follows from the overall pressure drop, Ap=}'.'~Api as G-qb~/Ap. The results are applied to analysing a vacuum system of the first Spacelab payload. (West Germany) H Hamaeher, Vacuum, 32 (12), 1982, 729 733.
12. G A S E O U S E L E C T R O N I C 3 12 5709. Development of laser diagnostic probes for chemical vapor deposition of InP/lnGaAsP epitaxiat layers. (USA) Laser spectroscopic methods have been developed for the detection of
PH 3, P> AsH 3, As2, InCl, and GaCI, using both tunable-dye-laser induced fluorescence and excimer laser excitation. These are the primary reactants participating in the chemical vapour deposition (CVD) of I n P / I n G a A s P epitaxial layers. Using a reaction tube designed to simulate a C V D growth reactor, the detection limits measured for all these species are well below those levels typically employed during layer growth. Specific applications are outlined, and several examples are given relating these techniques to conditions expected in I n P / l n G a A s P layer growth. V M Donnelly and R F Karlicek, J Appl Phys, 53 (9), 1982, 6399~407. 12 5710. A simplified hybrid detector for ion counting. (GB) A hybrid detector for ion counting which utilizes an ion-to-electron converter, an electron multiplier and a scintillation counter is described. A coaxial geometry and simple dynode structure of the electron multiplier facilitates the conversion of existing Daly-type detectors to the hybrid type. This detector is shown to have very low background in pulse counting of both negative and positive ions. The circuitry used facilitates conversion from positive- to negative-ion detection modes and, like the Daly detector, requires only one power supply in addition to the photomultiplier tube supply. (USA) D B Wittry and F Gun, J Phvs E: Sci Instrum, 15 (8), 1982, 834 838. 12 5711. Refractive Q-switching of a ruby laser by a moving plasma. (USA) A ruby laser was Q-switched by means of a plasma. The plasma, which had a density of up to 10 Is cm 3, was produced in an electromagnetic shock tube. The density gradient created by the reflected plasma was large enough to produce measurable refraction of the laser beam. The laser cavity, which was initially misaligned, attained perfect alignment when the plasma was introduced into the cavity. M Dembinski and P K John, Appl Optics, 21 (20), 1982, 3725 3727. 12 5712. Acoustic phenomena associated with a TEA laser discharge. (GB) Using a heterodyne technique o f considerably greater sensitivity than interfometry, we have studied acoustic effects arising from a TEA laser discharge. Initial adiabatic expansion was observed to be followed by a slow (tens of milliseconds) diffusive relaxation process. Shock waves generated in the vicinity of the cathode and also produced by the preionizing arc arrays caused perturbations on a time-scale of tens of microseconds. Discharge heating of the gas caused it to expand by almost an order less than the adiabatic expansion or shock tube theories would suggest. The implications of these findings to the design of high repetition rate and frequency stable TEA lasers are discussed. M R Harris and D V Willets, J Phys D: Appl Phys, 16 (2), 1983, 125 133. 12 5713. Random walk of cathode arc spots in vacuum. (GB) The cathode spot movement of a vacuum arc with AI, Cd, Mo and Cu cathodes was investigated. Provided external disturbances are absent the cathode spot was found to move at random. The two-dimensional distributions of spot displacements can be described by a Rayleigh function. From the experimental data the average distances between cathode craters were deduced, leading to values of 2 3 times the crater 223
Pergamon Press Ltd
Prtnted in Great Britain
Classified abstracts 5706-5894 Classified abstracts 5 7 0 6 - 5 7 1 3 on this page
Compiled by H K h e y r a n d i s h ,
University of Salford
Editor's N o t e The label immediately following the title of each item denotes country of origin of publication, and that at the end of each abstract indicates country of origin of work (where known)
I. G e n e r a l v a c u u m science and e n g i n e e r i n g 10. K I N E T I C T H E O R Y O F GASES 10 5706. Viscoelastic flow past an infinite plate with suction and constant heat flux. (GB) While studying the viscoelastic flow past an infinite plate with suction and constant heat flux between fluid and plate with suction and constant heat flux between fluid and plate, Raptis and Tzivanidis gave the solution of a pair of equations for velocity and temperature as functions of distance. They then gave some approximate solutions. This letter shows that the approximation are not justified and presents an exact analytical study. (India) A K Sanyal and D Ray, J Phys D: Appl Phys, 16 (2), 1983, 17 22. 10 5707. A system for phase and intermittency measurements in periodically turbulent flows. (GB) A measuring system is described which maps the spatial and temporal positions of the periodic turbulent bursts which appear in the boundary layer growing on a surface immersed in an oscillatory travelling-wave type of flow. The basic principle of the system is that whereby a "window" of controllable duration and phase relative to the oscillatory flow is opened and the flow is observed during this opening to examine whether it is laminar or turbulent. The system uses both analogue signal-processing components and digital circuitry under the control of a programmable desk calculator. Some typical results are presented for the growth of tmbulent patches in the boundary layer on a flat plate mounted in one of the Q M C gust tunnels. G Siderides and L Bernstein, J Phys E: Sci hlstrum, 16 (2), 1983, 136 141.
11. GASES A N D SOLIDS 11 5708. An analytical approach for calculating vacuum properties of outgassing tubing systems. (GB) A method has been investigated to calculate vacuum properties, such as flow conductance and pressure drop, for complex tubing systems, taking into account the outgassing of the tube walls. The procedure is based on the determination of the pressure drop, Apl, of each tube element, starting at the chamber with a given mass flow rate. qh~-The flow conductance, G, of the system follows from the overall pressure drop, Ap=}'.'~Api as G-qb~/Ap. The results are applied to analysing a vacuum system of the first Spacelab payload. (West Germany) H Hamaeher, Vacuum, 32 (12), 1982, 729 733.
12. G A S E O U S E L E C T R O N I C 3 12 5709. Development of laser diagnostic probes for chemical vapor deposition of InP/lnGaAsP epitaxiat layers. (USA) Laser spectroscopic methods have been developed for the detection of
PH 3, P> AsH 3, As2, InCl, and GaCI, using both tunable-dye-laser induced fluorescence and excimer laser excitation. These are the primary reactants participating in the chemical vapour deposition (CVD) of I n P / I n G a A s P epitaxial layers. Using a reaction tube designed to simulate a C V D growth reactor, the detection limits measured for all these species are well below those levels typically employed during layer growth. Specific applications are outlined, and several examples are given relating these techniques to conditions expected in I n P / l n G a A s P layer growth. V M Donnelly and R F Karlicek, J Appl Phys, 53 (9), 1982, 6399~407. 12 5710. A simplified hybrid detector for ion counting. (GB) A hybrid detector for ion counting which utilizes an ion-to-electron converter, an electron multiplier and a scintillation counter is described. A coaxial geometry and simple dynode structure of the electron multiplier facilitates the conversion of existing Daly-type detectors to the hybrid type. This detector is shown to have very low background in pulse counting of both negative and positive ions. The circuitry used facilitates conversion from positive- to negative-ion detection modes and, like the Daly detector, requires only one power supply in addition to the photomultiplier tube supply. (USA) D B Wittry and F Gun, J Phvs E: Sci Instrum, 15 (8), 1982, 834 838. 12 5711. Refractive Q-switching of a ruby laser by a moving plasma. (USA) A ruby laser was Q-switched by means of a plasma. The plasma, which had a density of up to 10 Is cm 3, was produced in an electromagnetic shock tube. The density gradient created by the reflected plasma was large enough to produce measurable refraction of the laser beam. The laser cavity, which was initially misaligned, attained perfect alignment when the plasma was introduced into the cavity. M Dembinski and P K John, Appl Optics, 21 (20), 1982, 3725 3727. 12 5712. Acoustic phenomena associated with a TEA laser discharge. (GB) Using a heterodyne technique o f considerably greater sensitivity than interfometry, we have studied acoustic effects arising from a TEA laser discharge. Initial adiabatic expansion was observed to be followed by a slow (tens of milliseconds) diffusive relaxation process. Shock waves generated in the vicinity of the cathode and also produced by the preionizing arc arrays caused perturbations on a time-scale of tens of microseconds. Discharge heating of the gas caused it to expand by almost an order less than the adiabatic expansion or shock tube theories would suggest. The implications of these findings to the design of high repetition rate and frequency stable TEA lasers are discussed. M R Harris and D V Willets, J Phys D: Appl Phys, 16 (2), 1983, 125 133. 12 5713. Random walk of cathode arc spots in vacuum. (GB) The cathode spot movement of a vacuum arc with AI, Cd, Mo and Cu cathodes was investigated. Provided external disturbances are absent the cathode spot was found to move at random. The two-dimensional distributions of spot displacements can be described by a Rayleigh function. From the experimental data the average distances between cathode craters were deduced, leading to values of 2 3 times the crater 223