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3060. Angular scattering in charge-exchanging beams: Implications for neutral beam formation via negative ions
Classified abstracts 3 0 5 2 - 3 0 6 2
31 3052. Refractive index of BaTiO3 and SrTiO3 films. (USA) Experimental data on the wavelength dependence of the refractive index in the wavelength range 0.3-1.0 ~,nl is presented for thin films of BaTiO3 and SrTiO3. The films of thickness I-4 i~tm were prepared by sputter deposition at substrate temperatures of 300 to 600 K, resulting in amorphous films at the lower temperatures and "microcrystalline" films at the higher. Both thin-film phases have a lower index at a given wavelength than the corresponding crystalline value (e.g., at A 5000 A, n = 2.00, 2.07, and 2.51 for amorphous, microcrystalline, and crystalline BaTiO3, respectively). The dispersion of the refiactive index in the thin films follows a singleoscillator model with a higher oscillator energy and smaller oscillator strength than in the crystalline phase. M W6hlecke et al, J ,4ppl Phys. 48 (4), 1977, 1748-1750. 3l 3053. Investigation of collision cascades in solids by transmission sputtering of thin foils. (Germany) A method is described, which enables the measurement of the depth distribution of the deposited energy by atomic collision cascades. It is based on the nleast, rement of the sputtering yield of thin selfsupporting polycrystalline films and was in partictdar tested for gold unter 500 keV argon ion bombardment. Bombardment with gold ions reveals both in transmission and for backsputtering a pronounced spike-effect. (Denmark) H L Bay et al, l,'akuum-Tech. 26 (3). 1977, 81-84 (in German).
32. EVACUATION AND SEALING 32 3054. A versatile pulsed plasma light source operating in the vacuum ultraviolet to visible wavelength region. (GB) A compact, flexible light source is described, operable at wavelengths from the visible to vacuum ultraviolet or below. It consists of a plasma produced by the ablation of a solid dielectric surface in the presence of an intense electric discharge. By modifying the control circuitry, stable radiant discharges of duration ranging from under 1 ~,s to over 10 ~,s and of variable spectral quality may be produced, having application in high-speed photography, plasma diagnostics, absorption spectroscopy and biological irradiation. B A Norton and E R Wooding, J Phys E." Scient h~strum, 10 (5), 1977, 493--495. 32 3055. "Integration' of a 1000 W hydrogen discharge lamp and a vacuum monochromator. (GB) A simple, rugged source of intense, stable monochromatized radiation in the vacuum ultraviolet has been constructed by "integrating" a hydrogen discharge lamp (power rating more than 1000 W) and an existing vacuum monochromator. The entrance slit of the monochromator has been redesigned and serves also as anode to the lamp. Hydrogen is leaked into the lamp while only the monochromator is pumped by a rotary pump. The lamp is most efficient when it is made to burn with a luminous blob of plasma at the entrance slit in the anode. It produces a flux per solid angle at the slit two orders of magnitude higher than the flux reported for an open hydrogen discharge lamp by Eastman and Donelon. (Netherlands) B J Mulder, ./Phys E: Scient Instrum, 10 (5), 1977,490-495. 32 3056. Carbon and graphite monofilaments as in-line electron beam energy monitors. (USA) Carbon and graphite monofilaments have been evaluated for in-line diagnostics of pulsed relativistic electron beams used in testing the dynamic thermomechanical response of materials. The monofilamerits are small enough to have negligible effect on the electron beams. This newly developed technique is capable of specific energy measurements from a few calories per gram to more than 1200. The measurement is made within a few microseconds, eliminating any need for time extrapolation to account for heat loss and permitting measurement before the active filament is destroyed by blowoff debris from spall or vaporization of adjacent material. D V Keller and D A Rice, Rev Sci Instrum, 48 (4), 1977, 427-431. 32 3057. The characteristics of a medium current relativistic electronbeam diode. (USA) In a previous paper we reported observation of ion flow in the
Ncreus diode. We report here more detailed observations of the diode, employing a Thomson parabola analyzer to measure ion species and energies, a four-pulse holographic interfcrometer to observe plasma blowoff from the electrodes, and an image-converter streak camera to record total optical radiation and time-resolved emission spectra. The large current on axis (the "pinch' current) of this diode appears to be caused by rapid local gap closure on axis. A model describing the behaviour of this diode is discussed and compared with experimental data. D W Swain et al, J Appl Phys. 48 (3), 1977, 1085-1093. 32 3058. Propagation of an unneutralized intense relativistic electron beam in a magnetic field. (USA) In this paper the results of a series of electron-beam vacuum propagation experiments are presented and compared with theoretical predictions. Important conclusions pertaining to time-dependent diode behaviour, virtual cathode formation, and various equilibrium and stability criteria are reported. R B Miller and D C Straw, J Appl Phys, 48 (3), 1977, 1061-1069.
33. NUCLEONICS 33 3059. Diagnostics for intense pulsed ion beams. (USA) Diagnostic methods pertinent to the probing of intense pulsed ion beams are described. Special emphasis is given to the measurement of delayed radioactivity from nuclear reactions induced in a target by the ions. This nuclear activation analysis provides the most precise, unambiguous means of determining the number of ions per pulse that is presently available. A compilation of yields and cross sections for several nuclear reactions is given. Included among the nuclear techniques is the measurement of prompt radiation such as 7 rays and neutrons from ion-induced reactions. In addition, a scintillatorphotodiode detector is described which has proven to be useful for the measurement of time of flight and which may be used to observe the relative pulse shape. Biased ion collectors and difficulties associated with their use are also discussed. F C Young et al, Rel, Sci lnstrum, 48 (4), 1977, 432-443. 33 3060. Angular scattering in charge-exchanging beams: Implications for neutral beam formation via negative ions. (USA) Coupled Boltzmann equations for particles with two charge states have been solved to describe the angular evolution of a beam which is charge exchanging through collisions with a background vapor. The solutions are applied to the processes D°+Cs---~-.D - ÷ C s + and D - - i Cs-->D°4 Cs + e using measured differential cross sections where available. By accelerating and stripping a D - beam, an intense high-energy beam can be formed for thermonuclear fusion experiments and reactors. It is concluded that angular scattering does not place a signifcant limit on the beam quality, although the cesium line density must be the minimum to reach a charge-state equilibrium in the beam. E B Hooper Jr and P A Willmann, J Appl Phys, 48 (3), 1977, 10411046. 33 3061. Adaptation of an ion microprobe for ion bombardment of liquid metals. (USA) A technique involving a new substage assembly was developed to permit an ion microprobe mass analyser (IMMA) to be used as an ion bombardment facility for molten metals (lithium) without harm to the instrument from the hot, reactive samples. A K Fischer et al, Rev Sci hlstrum, 48 (3), 1977, 219-220.
34. ELECTRONICS AND HIGH ALTITUDE PHYSICS AND TECHNOLOGY 3062. Self-scattering cross section of molecules in a beam. (USA) Molecular collision cross sections have always been measured by the beam scattering method, or by the measurements of thermal conductivity and/or viscosity coefficient, etc. The cross sections thus obtained have been found to be different quantitatively from that
657
31 3052. Refractive index of BaTiO3 and SrTiO3 films. (USA) Experimental data on the wavelength dependence of the refractive index in the wavelength range 0.3-1.0 ~,nl is presented for thin films of BaTiO3 and SrTiO3. The films of thickness I-4 i~tm were prepared by sputter deposition at substrate temperatures of 300 to 600 K, resulting in amorphous films at the lower temperatures and "microcrystalline" films at the higher. Both thin-film phases have a lower index at a given wavelength than the corresponding crystalline value (e.g., at A 5000 A, n = 2.00, 2.07, and 2.51 for amorphous, microcrystalline, and crystalline BaTiO3, respectively). The dispersion of the refiactive index in the thin films follows a singleoscillator model with a higher oscillator energy and smaller oscillator strength than in the crystalline phase. M W6hlecke et al, J ,4ppl Phys. 48 (4), 1977, 1748-1750. 3l 3053. Investigation of collision cascades in solids by transmission sputtering of thin foils. (Germany) A method is described, which enables the measurement of the depth distribution of the deposited energy by atomic collision cascades. It is based on the nleast, rement of the sputtering yield of thin selfsupporting polycrystalline films and was in partictdar tested for gold unter 500 keV argon ion bombardment. Bombardment with gold ions reveals both in transmission and for backsputtering a pronounced spike-effect. (Denmark) H L Bay et al, l,'akuum-Tech. 26 (3). 1977, 81-84 (in German).
32. EVACUATION AND SEALING 32 3054. A versatile pulsed plasma light source operating in the vacuum ultraviolet to visible wavelength region. (GB) A compact, flexible light source is described, operable at wavelengths from the visible to vacuum ultraviolet or below. It consists of a plasma produced by the ablation of a solid dielectric surface in the presence of an intense electric discharge. By modifying the control circuitry, stable radiant discharges of duration ranging from under 1 ~,s to over 10 ~,s and of variable spectral quality may be produced, having application in high-speed photography, plasma diagnostics, absorption spectroscopy and biological irradiation. B A Norton and E R Wooding, J Phys E." Scient h~strum, 10 (5), 1977, 493--495. 32 3055. "Integration' of a 1000 W hydrogen discharge lamp and a vacuum monochromator. (GB) A simple, rugged source of intense, stable monochromatized radiation in the vacuum ultraviolet has been constructed by "integrating" a hydrogen discharge lamp (power rating more than 1000 W) and an existing vacuum monochromator. The entrance slit of the monochromator has been redesigned and serves also as anode to the lamp. Hydrogen is leaked into the lamp while only the monochromator is pumped by a rotary pump. The lamp is most efficient when it is made to burn with a luminous blob of plasma at the entrance slit in the anode. It produces a flux per solid angle at the slit two orders of magnitude higher than the flux reported for an open hydrogen discharge lamp by Eastman and Donelon. (Netherlands) B J Mulder, ./Phys E: Scient Instrum, 10 (5), 1977,490-495. 32 3056. Carbon and graphite monofilaments as in-line electron beam energy monitors. (USA) Carbon and graphite monofilaments have been evaluated for in-line diagnostics of pulsed relativistic electron beams used in testing the dynamic thermomechanical response of materials. The monofilamerits are small enough to have negligible effect on the electron beams. This newly developed technique is capable of specific energy measurements from a few calories per gram to more than 1200. The measurement is made within a few microseconds, eliminating any need for time extrapolation to account for heat loss and permitting measurement before the active filament is destroyed by blowoff debris from spall or vaporization of adjacent material. D V Keller and D A Rice, Rev Sci Instrum, 48 (4), 1977, 427-431. 32 3057. The characteristics of a medium current relativistic electronbeam diode. (USA) In a previous paper we reported observation of ion flow in the
Ncreus diode. We report here more detailed observations of the diode, employing a Thomson parabola analyzer to measure ion species and energies, a four-pulse holographic interfcrometer to observe plasma blowoff from the electrodes, and an image-converter streak camera to record total optical radiation and time-resolved emission spectra. The large current on axis (the "pinch' current) of this diode appears to be caused by rapid local gap closure on axis. A model describing the behaviour of this diode is discussed and compared with experimental data. D W Swain et al, J Appl Phys. 48 (3), 1977, 1085-1093. 32 3058. Propagation of an unneutralized intense relativistic electron beam in a magnetic field. (USA) In this paper the results of a series of electron-beam vacuum propagation experiments are presented and compared with theoretical predictions. Important conclusions pertaining to time-dependent diode behaviour, virtual cathode formation, and various equilibrium and stability criteria are reported. R B Miller and D C Straw, J Appl Phys, 48 (3), 1977, 1061-1069.
33. NUCLEONICS 33 3059. Diagnostics for intense pulsed ion beams. (USA) Diagnostic methods pertinent to the probing of intense pulsed ion beams are described. Special emphasis is given to the measurement of delayed radioactivity from nuclear reactions induced in a target by the ions. This nuclear activation analysis provides the most precise, unambiguous means of determining the number of ions per pulse that is presently available. A compilation of yields and cross sections for several nuclear reactions is given. Included among the nuclear techniques is the measurement of prompt radiation such as 7 rays and neutrons from ion-induced reactions. In addition, a scintillatorphotodiode detector is described which has proven to be useful for the measurement of time of flight and which may be used to observe the relative pulse shape. Biased ion collectors and difficulties associated with their use are also discussed. F C Young et al, Rel, Sci lnstrum, 48 (4), 1977, 432-443. 33 3060. Angular scattering in charge-exchanging beams: Implications for neutral beam formation via negative ions. (USA) Coupled Boltzmann equations for particles with two charge states have been solved to describe the angular evolution of a beam which is charge exchanging through collisions with a background vapor. The solutions are applied to the processes D°+Cs---~-.D - ÷ C s + and D - - i Cs-->D°4 Cs + e using measured differential cross sections where available. By accelerating and stripping a D - beam, an intense high-energy beam can be formed for thermonuclear fusion experiments and reactors. It is concluded that angular scattering does not place a signifcant limit on the beam quality, although the cesium line density must be the minimum to reach a charge-state equilibrium in the beam. E B Hooper Jr and P A Willmann, J Appl Phys, 48 (3), 1977, 10411046. 33 3061. Adaptation of an ion microprobe for ion bombardment of liquid metals. (USA) A technique involving a new substage assembly was developed to permit an ion microprobe mass analyser (IMMA) to be used as an ion bombardment facility for molten metals (lithium) without harm to the instrument from the hot, reactive samples. A K Fischer et al, Rev Sci hlstrum, 48 (3), 1977, 219-220.
34. ELECTRONICS AND HIGH ALTITUDE PHYSICS AND TECHNOLOGY 3062. Self-scattering cross section of molecules in a beam. (USA) Molecular collision cross sections have always been measured by the beam scattering method, or by the measurements of thermal conductivity and/or viscosity coefficient, etc. The cross sections thus obtained have been found to be different quantitatively from that
657