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4986. Polarized He (23S) thermal metastable atom source
Classified
abstracts
49824992
36 4982. Beam source for moderately fast neutral alkali atoms. (USA) In certain applications the linear arrangement of ion source and charge exchange chamber in standard charge sources for neutral atomic beams leads to undesirable stray light. To avoid this problem a new design has been developed and tested. The maximum beam flux emerging from this source is2.0 x 10” atomss-’ mm-’ at the energy E = 100 eV. The energy spread AE/EsO.S?;. The angular spread is about 0.47 deg FWHM. Adjusting the ion optics every 100 hours the intensity of the neutral beam has been measured to be stable within 10% over a period of 400 hours. (West Germany) S Kita et al, Rev Sci Instrum. 52 (5), 1981, 684488. 36 4983. Source plasma characteristics of the coaxial duoPfGatron ion source. (USA) A new variation of the duoPIGatron ion source, the coaxial duoPIGatron ion source, has been built and tested. A distinctive feature of this source is the coaxially-shaped intermediate electrode formed by a magnetic centre pole and an intermediate electrode chamber. The source generated a dense uniform plasma over a grid of 18.5 cm diameter and produced ion beams of 30 A at 30 kV stably and efficiently. The coaxial intermediate electrode worked well at a fixed ratio between the centre pole coil current and source coil current, indicating that the magnetic nozzle has successfully connected the cathode with source plasma region. An increase of the applied magnetic field did not effect the density profile, and it raised the arc eficiency. The arc efficiency reached 1.5 A/kW at the source coil current of 30 A when the operation of the source was most stable. The ion species fraction was measured and the proton ratio was increased to 70% from 60”/, of the modified duoPIGatron. (Japan) Hiroshi Horiike et al, Ret Sci Insrrum. 52 (4), 1981, 567-571. 36 4984. Liquid metal source of gold ions. (USA) A fully engineered liquid metal field emission source of gold ions has been developed, operating with low heater power (~30 W) and without forced cooling. The design and performance of the source are described in detail. The present design can also be used to produce sources of a variety of elements. other than gold. including tin, bismuth, and lead. It provides a versatile and reliable research tool which is fully compatible with uhv mstallations. Potential fields of apphcation include materials development and surface analysis. (GB) P D Prewett et al, Rev Sci Iustrum. 52 (4), 1981, 562.-564. 36 4985. Continuous flow reflux oven as the source of an effusive molecular Cs beam. (USA) The design and the operation of a continuous Aow reflux (CFR) oven used for the formation of an effusive Cs molecular beam which is compatible with ultrahigh vacuum (10e9 torr) conditions are described. The CFR oven operation utilizes capillary action to recycle the unused part of the Cs molecular beam. A possibihty of extending the principle to supersonic beam pressures is discussed. (Israel) R D Swenumson and U Even, Rer Sci It7.strum. 52 (4). 1981, 559-561. 36 4986. Polarized He (2%) thermal metastahle atom source. (USA) A source of polarized He (2%) metastable atoms is described that provides a thermal energy beam with a flux of the order of - lOI metastables s-’ steradian’ at a polarization P; - 501,,. The polarization of the beam can be simply reversed, or modulated. without changing the beam trajectory or flux. The beam contains no significant admtxtures of He(2’S) atoms, photons. or fast neutrals and is suitable for use in a wide variety ofcollision and surface physics experiments. T W Riddle et al. Rer Sci In.sfrum, 52 (6). 1981, 797-801. 36 4987. Beams steering and diffraction of magnetostatic backward volume waves. (USA) This paper reports theoretical calculations of the beam spreading of magnetostatic backward volume waves (MSBVW’s) arising from the finite length of practical transducers. The calculations include the beam steering effects resulting from the pronounced anisotropy of MSBVW propagation. The predicted beam spreadmg of MSBVW’s is significantly larger than that of SAW’s on YZ LiNbO,. On the other hand, based on comparison with reported experimental results on the beam spreading of magnetostatic surface waves (MSSW’s), it would appear that MSBVW’s suffer smaller beam spreading than MSSW’s. S P Parekh and H S Tuan. J Appl Phys. 52 (31, 1981. 2279-2281. 220
3h 4988. Large acceptance angle retarding-potential analyzers. (USA) Electrostatic retarding-potential gridded analysers have been used to measure the current and the axial energy distribution of ions escaping along magnetic field lines in the ZXIIB magnetic fusion experiment at Lawrence Livermore National Laboratory (LLNL). Two analysers are discussed: a large scanning analyser with a movable entrance aperture that can measure ion losses from a different segment of the plasma diameter on each shot, and a smaller analyser that mounts in 5-cm-diam. ports. Careful electronmagnetic shielding and grounding were necessary in order to reduce spurious signals. Accurate measurements of ion current require grids that attenuate the plasma flow and isolate it from the analyser grid potentials. several techniques to suppress secondary and primary electrons. and consideration of the space-charge limits as well as techniques to increase these limits. Accurate measurements of ion energy require, in addition, confining large-angle ton orbits within the analyser by an axial magnetic field, limiting the sweep rate of the ion-repeller grid. and aligning the analyser so that it is normal to the magnetic lield hnes. (The analysers are also used on the Tandem Mirror Experiment, TMX, where the angular acceptance requirements are reduced). The analysers measure the axial energy, which in ZXIIB and TMX is much greater than the transverse energy. Several pitfalls and their cures are identified in the design, construction, and operation of these analysers. Arthur W Molvik, Rer Sci Insrrum. 52 (5). 1981. 704-711. 36 4989. Energy spectrum diagnostics for collectively accelerated proton beams. (USA) An account is presented of the proton energy spectrum diagnostic techniques employed in a Collective Ion Accelerator study. The emphasis is on a newly developed neutron time of flight diagnostic which yields the complete (E > 2.5 MeV) proton spectrum on every shot. A brief account is also presented of the stacked foil activation technique employed, and results from the two measurements are compared. Finally, we describe a stacked foil Faraday cup which provides temporal resolution of the proton acceleration. R J Adler et al, Rev Sci Insrrum, 52 (5). 1981. 698-703. 36 4990. Novel charged particle analyser for momentum determination in the multichanneling mode: I. Design aspects and electron/ion optical properties. (USA) We present a novel electrostatic. energy-disperstve particle analyser whose astigmatism can be used to measure the polar angle distribution of charged particles originating m a sample spot. in a multichanneling mode. The analyser consists of a toroidal prism and a truncated conical lens, both coaxial on an axis through the particle source. The toroidal prism is used in an unsual way, in that the axial radius of the central equipotential surface varies from infinity to a certain minimal value for varying deflection angles in the prism. We develop design criteria for an analyser using this principle, suitable for measurements on solid samples. The energy resolution of the analyser hes between those of a 127’ cylindrical and of a 180. spherical analyser. Angular resolutions of ~2.6” (FWHM) can be achieved. (West Germany) H A Engelhardt et al, Rev Sci lnsrrum, 52 (6). 1981, 835-839. 36 4991. Diagnostic system of the Lawrence Livermore National Laboratory two-stage light-gas gun. (USA) A two-stage light-gas gun is used for a variety of dynamic physicalproperty measurements at 100 GPa (1 Mbar) pressures. The diagnostic system described here consists of a flash X-ray system to measure impactor velocity, detectors and electronics to measure shock-wave velocities with subnanosecond resolution, and data-analysis techniques that permit us to measure the tilt and distortlon of the Impactor and of the resulting shock front. We describe our methods for safely purging hydrogen gas from the system after each shot. A C Mitchell and W J Nellis, Rer Sci Insrrum. 52. (3). 1981, 347-359. 36 4992. CW far-infrared laser-scattering apparatus for plasma wave studies. (USA) A description of the design and construction of the first cw far-infrared laser-scattering apparatus for the study of the frequency and wavenumber spectra of plasma density fluctuations is given. Scattering results from both a controlled laboratory plasma and the UCLA Microtor tokamak are discussed. W A Peebles et al. Rev Sri Ittsrrum. 52 (3), 1981. 360--370.
abstracts
49824992
36 4982. Beam source for moderately fast neutral alkali atoms. (USA) In certain applications the linear arrangement of ion source and charge exchange chamber in standard charge sources for neutral atomic beams leads to undesirable stray light. To avoid this problem a new design has been developed and tested. The maximum beam flux emerging from this source is2.0 x 10” atomss-’ mm-’ at the energy E = 100 eV. The energy spread AE/EsO.S?;. The angular spread is about 0.47 deg FWHM. Adjusting the ion optics every 100 hours the intensity of the neutral beam has been measured to be stable within 10% over a period of 400 hours. (West Germany) S Kita et al, Rev Sci Instrum. 52 (5), 1981, 684488. 36 4983. Source plasma characteristics of the coaxial duoPfGatron ion source. (USA) A new variation of the duoPIGatron ion source, the coaxial duoPIGatron ion source, has been built and tested. A distinctive feature of this source is the coaxially-shaped intermediate electrode formed by a magnetic centre pole and an intermediate electrode chamber. The source generated a dense uniform plasma over a grid of 18.5 cm diameter and produced ion beams of 30 A at 30 kV stably and efficiently. The coaxial intermediate electrode worked well at a fixed ratio between the centre pole coil current and source coil current, indicating that the magnetic nozzle has successfully connected the cathode with source plasma region. An increase of the applied magnetic field did not effect the density profile, and it raised the arc eficiency. The arc efficiency reached 1.5 A/kW at the source coil current of 30 A when the operation of the source was most stable. The ion species fraction was measured and the proton ratio was increased to 70% from 60”/, of the modified duoPIGatron. (Japan) Hiroshi Horiike et al, Ret Sci Insrrum. 52 (4), 1981, 567-571. 36 4984. Liquid metal source of gold ions. (USA) A fully engineered liquid metal field emission source of gold ions has been developed, operating with low heater power (~30 W) and without forced cooling. The design and performance of the source are described in detail. The present design can also be used to produce sources of a variety of elements. other than gold. including tin, bismuth, and lead. It provides a versatile and reliable research tool which is fully compatible with uhv mstallations. Potential fields of apphcation include materials development and surface analysis. (GB) P D Prewett et al, Rev Sci Iustrum. 52 (4), 1981, 562.-564. 36 4985. Continuous flow reflux oven as the source of an effusive molecular Cs beam. (USA) The design and the operation of a continuous Aow reflux (CFR) oven used for the formation of an effusive Cs molecular beam which is compatible with ultrahigh vacuum (10e9 torr) conditions are described. The CFR oven operation utilizes capillary action to recycle the unused part of the Cs molecular beam. A possibihty of extending the principle to supersonic beam pressures is discussed. (Israel) R D Swenumson and U Even, Rer Sci It7.strum. 52 (4). 1981, 559-561. 36 4986. Polarized He (2%) thermal metastahle atom source. (USA) A source of polarized He (2%) metastable atoms is described that provides a thermal energy beam with a flux of the order of - lOI metastables s-’ steradian’ at a polarization P; - 501,,. The polarization of the beam can be simply reversed, or modulated. without changing the beam trajectory or flux. The beam contains no significant admtxtures of He(2’S) atoms, photons. or fast neutrals and is suitable for use in a wide variety ofcollision and surface physics experiments. T W Riddle et al. Rer Sci In.sfrum, 52 (6). 1981, 797-801. 36 4987. Beams steering and diffraction of magnetostatic backward volume waves. (USA) This paper reports theoretical calculations of the beam spreading of magnetostatic backward volume waves (MSBVW’s) arising from the finite length of practical transducers. The calculations include the beam steering effects resulting from the pronounced anisotropy of MSBVW propagation. The predicted beam spreadmg of MSBVW’s is significantly larger than that of SAW’s on YZ LiNbO,. On the other hand, based on comparison with reported experimental results on the beam spreading of magnetostatic surface waves (MSSW’s), it would appear that MSBVW’s suffer smaller beam spreading than MSSW’s. S P Parekh and H S Tuan. J Appl Phys. 52 (31, 1981. 2279-2281. 220
3h 4988. Large acceptance angle retarding-potential analyzers. (USA) Electrostatic retarding-potential gridded analysers have been used to measure the current and the axial energy distribution of ions escaping along magnetic field lines in the ZXIIB magnetic fusion experiment at Lawrence Livermore National Laboratory (LLNL). Two analysers are discussed: a large scanning analyser with a movable entrance aperture that can measure ion losses from a different segment of the plasma diameter on each shot, and a smaller analyser that mounts in 5-cm-diam. ports. Careful electronmagnetic shielding and grounding were necessary in order to reduce spurious signals. Accurate measurements of ion current require grids that attenuate the plasma flow and isolate it from the analyser grid potentials. several techniques to suppress secondary and primary electrons. and consideration of the space-charge limits as well as techniques to increase these limits. Accurate measurements of ion energy require, in addition, confining large-angle ton orbits within the analyser by an axial magnetic field, limiting the sweep rate of the ion-repeller grid. and aligning the analyser so that it is normal to the magnetic lield hnes. (The analysers are also used on the Tandem Mirror Experiment, TMX, where the angular acceptance requirements are reduced). The analysers measure the axial energy, which in ZXIIB and TMX is much greater than the transverse energy. Several pitfalls and their cures are identified in the design, construction, and operation of these analysers. Arthur W Molvik, Rer Sci Insrrum. 52 (5). 1981. 704-711. 36 4989. Energy spectrum diagnostics for collectively accelerated proton beams. (USA) An account is presented of the proton energy spectrum diagnostic techniques employed in a Collective Ion Accelerator study. The emphasis is on a newly developed neutron time of flight diagnostic which yields the complete (E > 2.5 MeV) proton spectrum on every shot. A brief account is also presented of the stacked foil activation technique employed, and results from the two measurements are compared. Finally, we describe a stacked foil Faraday cup which provides temporal resolution of the proton acceleration. R J Adler et al, Rev Sci Insrrum, 52 (5). 1981. 698-703. 36 4990. Novel charged particle analyser for momentum determination in the multichanneling mode: I. Design aspects and electron/ion optical properties. (USA) We present a novel electrostatic. energy-disperstve particle analyser whose astigmatism can be used to measure the polar angle distribution of charged particles originating m a sample spot. in a multichanneling mode. The analyser consists of a toroidal prism and a truncated conical lens, both coaxial on an axis through the particle source. The toroidal prism is used in an unsual way, in that the axial radius of the central equipotential surface varies from infinity to a certain minimal value for varying deflection angles in the prism. We develop design criteria for an analyser using this principle, suitable for measurements on solid samples. The energy resolution of the analyser hes between those of a 127’ cylindrical and of a 180. spherical analyser. Angular resolutions of ~2.6” (FWHM) can be achieved. (West Germany) H A Engelhardt et al, Rev Sci lnsrrum, 52 (6). 1981, 835-839. 36 4991. Diagnostic system of the Lawrence Livermore National Laboratory two-stage light-gas gun. (USA) A two-stage light-gas gun is used for a variety of dynamic physicalproperty measurements at 100 GPa (1 Mbar) pressures. The diagnostic system described here consists of a flash X-ray system to measure impactor velocity, detectors and electronics to measure shock-wave velocities with subnanosecond resolution, and data-analysis techniques that permit us to measure the tilt and distortlon of the Impactor and of the resulting shock front. We describe our methods for safely purging hydrogen gas from the system after each shot. A C Mitchell and W J Nellis, Rer Sci Insrrum. 52. (3). 1981, 347-359. 36 4992. CW far-infrared laser-scattering apparatus for plasma wave studies. (USA) A description of the design and construction of the first cw far-infrared laser-scattering apparatus for the study of the frequency and wavenumber spectra of plasma density fluctuations is given. Scattering results from both a controlled laboratory plasma and the UCLA Microtor tokamak are discussed. W A Peebles et al. Rev Sri Ittsrrum. 52 (3), 1981. 360--370.