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1303. Thin-film breakdown counter of fission fragments
Classified abstracts 1299-l
310 30
1299. Injection of ions into glass from a glow discharge. (USA)
Glow discharges have been used to inject singly charged ions into soda-lime-silicate glass at ~300°C. Ion injection has been confirmed for ions such as Ni+, Nb+, MO+, Ta+, etc, using X-ray fluorescence analysis, Auger spectroscopy, and ion scattering spectroscopy. A model based on the band structure of SiO, predicts that -80% of all elements (those with ionization energies less than -10 eV) can be injected into a silicate glass from a glow discharge. D E Carlson and C E Tracy, J AppZPhys, 46 (4), 1975, 1575-1580. 30 1300. Argon entrapment
in metal films by dc triode sputtering.
(USA) Sputtered films of 12 elementary metals were analysed for argon content by an rf spark-source mass-spectrographic method. All films were deposited using dc triode sputtering under similar conditions. Corrections in the data have been made to account for variations in target size and deposition rate. The experimental results are compared with sticking probabilities calculated using the Born-Mayer interatomic potentials; the agreement is fair except for elements having low atomic numbers, e.g., Cu and lower. The data confirm the role of reflected argon atoms in the entrapment mechanism at the substrat+as the atomic mass of the target material increases, the average energy of the reflected energetic argon atoms also increases, leading to the increased argon content in the film. The data also suggest that the entrapped argon content is dependent upon the atomic spacing of the film material. W W Y Lee and D Oblas, J Appf Phys, 46 (4), 1975, 1728-1732. 30 1301. Heavy-ion sputtering yield of silicon. (USA) The sputtering yield for 45-keV Ar+ irradiation of amorphous
silicon is found to be in very good agreement with theory. In connection with earlier reported yields measured relative to those of argon, we here report absolute yields for 16 different ions (7 I Z, C 83). In no case does the difference between theory and experiment amount to more than 15 ‘A. The energy dependence of lead sputtering yield on silicon (25 keV I E i 500 keV) is also reported and found to agree with theory. (Denmark) H H Andersen and H L Bay, J Appl Phys, 46 (5), 1975, 1919-1921.
L Tommasino
33. GENERAL
et al, J Appl Phys, 46 (4), 1975, 1484-1488.
PHYSICS
AND ELECTRONICS
33 1304. Ion beam profile monitor. (USA) An ion beam profile monitor, which consists of a two-dimensional array of sample points placed in the beam, is described. The monitor provides an accurate and unambiguous display of the beam profile on a laboratory oscilloscope. Performance of the monitor under various ion beam conditions is presented. E P EerNisse et al, Rev Sri Instrum, 46 (3), 1975, 266268. 1305. Electron beam current controller for LEED-Auger
33 studies. (GB)
A control circuit is described which maintains a constant incident beam current for LEED-Auger electron guns. Significant in the design are isolation of control circuitry and gun by means of a solid state optical coupler, control based on true beam current, and adaptability of circuit to existing equipment. Control to better than 0.5 % is possible for beam currents between 0.1-100 pA. M Baines te al, J Phys E: Scient Znstrum, 8 (4), 1975, 305-307. 33 1306. The production of focused ion beams for surface and gas-phase collision studies. (GB)
Factors limiting the performance of practical ion beam systems are discussed and include momentum dispersion, instabilities, spacecharge repulsion and extraction optics. An approach to overall design is illustrated by an accelerator system employing low energy extraction and used for a range of working conditions and ion species. R E Hurley, Vacuum, 25 (4), 1975, 143-149. 33 1307. Molecular beam scattering from solid surfaces. (Germany)
Scattering of thermal atoms and molecules on solid surfaces has become an important and interesting field in surface physics. In this paper the most recent results of several groups are presented which were reported on the 2nd ICSS from 25-29 March 1974 in Kyoto. H Wilsch, Vacuum-Tech,
24 (2), 1975, 43-52 (in German).
1308. Scattering of helium and deuterium from single-crystal compared from two different laboratories. (USA)
32. NUCLEONICS 32 1302. The measurement
dioxide detectors. The detectors offer immediate information on the magnitude of particle fluxes and may possibly serve to identify the particles. (Italy)
of the radial ion temperature
distribution
in a
low-density plasma.
Density and temperature profiles (for both ions and electrons) and plasma rotation measurements are required for a detailed comparison between the properties of collisionless drift waves obtained with hydrogen plasma on the ODE experiment and the linear theory. Whenever these quantities cannot be measured by the simple electrostatic probe technique it is necessary to turn to spectroscopic techniques. Such a technique has been used here, and very accurate measurements of the Doppler broadening of the Hb line at 4862 A (H atoms being heated by charge exchange) give the ion temperature radial profiles for different experimental conditions in a low-density plasma (n = log-10”’ cmm3, T, = 13 eV, T, = 1 eV, and B. = l-3 kG). The improved spectroscopic system used is sufficiently sensitive for the plasma rotation to be measured where the azimuthal velocity is 10 times lower than the ion thermal velocity. This observation confirms the existence of a radial electric field E(r) in the plasma. The measurement of the rotation enables the frequency shifts of the unstable oscillations occurring in the laboratory frame to be investigated and an observed flute-type instability to be attributed to the centrifugal force arising from this E x B drift motion. (France) L A Hafez et al, JPhyJ D: Appl Phys, 8 (4), 1975, 374382. 32 1303. Thin-film breakdown counter of fission fragments.
(USA) A new kind of detector of heavy fission fragments is described. The detector is a thin-film capacitor in which electrical breakdowns are nonshorting. The detection is based on the counting of breakdowns which arise when heavy fission fragments hit the capacitor. These breakdowns occur at fields distinctly lower than those due to the application of the field only. The lowering of the breakdown field is discussed considering the thermal or electronic effects for silicon
33 Pt(ll1)
The angular distributions of scattered beams of helium and deuterium from platinum (I 11) surfaces which are obtained by two different laboratories using different techniques are compared. A basis for quantitative comparison of such inter-laboratory results is proposed. (Alp) S L Bernasek et al, J Vat Sci Technol, 12 (2), 1975, 655-657. 33 1309. The assignment of ion currents detected in the mass spectrum of a molecular beam. (GB)
A technique for assigning ion currents detected in the mass spectra of molecular beams is described with reference to the particular case of a molecular beam generated from a Knudsen effusion oven containing InP. Areas where the technique would find application are suggested. R F C Farrow, J Phys D: Appl Phys, 8 (4), 1975, L48-L52. 33 1310. Surface analysis with heavy ion induced Auger electrons; basic properties of a new method for materials sciences. (GB) Heavy ion induced Auger electron spectroscopy is presented as a new tool for surface analysis. In contrast to conventional Auger electron spectroscopy using electron excitation, the new technique offers the advantage of selective excitation of specific impurity elements present in a solid matrix by choosing a proper value of projectile mass and projectile energy. The technique is characterized by very fast rising cross-sections at threshold. The cross-sections can be very large in comparison to electron excitation. Due to the high energy loss of heavy ions at the energies applied, the projectiles are probing a very thin surface layer of the sample. Another benefit of heavy ion excitation is the possibility of simultaneous detection of back scattered heavy ions as well as the possibility for detection of ultra soft X-rays. In this way three complementary techniques are available simultaneously for mutual comparison. (Germany) K 0 Groeneveld et al, Vacuum, 25 (l), 1975,9-12. 459
310 30
1299. Injection of ions into glass from a glow discharge. (USA)
Glow discharges have been used to inject singly charged ions into soda-lime-silicate glass at ~300°C. Ion injection has been confirmed for ions such as Ni+, Nb+, MO+, Ta+, etc, using X-ray fluorescence analysis, Auger spectroscopy, and ion scattering spectroscopy. A model based on the band structure of SiO, predicts that -80% of all elements (those with ionization energies less than -10 eV) can be injected into a silicate glass from a glow discharge. D E Carlson and C E Tracy, J AppZPhys, 46 (4), 1975, 1575-1580. 30 1300. Argon entrapment
in metal films by dc triode sputtering.
(USA) Sputtered films of 12 elementary metals were analysed for argon content by an rf spark-source mass-spectrographic method. All films were deposited using dc triode sputtering under similar conditions. Corrections in the data have been made to account for variations in target size and deposition rate. The experimental results are compared with sticking probabilities calculated using the Born-Mayer interatomic potentials; the agreement is fair except for elements having low atomic numbers, e.g., Cu and lower. The data confirm the role of reflected argon atoms in the entrapment mechanism at the substrat+as the atomic mass of the target material increases, the average energy of the reflected energetic argon atoms also increases, leading to the increased argon content in the film. The data also suggest that the entrapped argon content is dependent upon the atomic spacing of the film material. W W Y Lee and D Oblas, J Appf Phys, 46 (4), 1975, 1728-1732. 30 1301. Heavy-ion sputtering yield of silicon. (USA) The sputtering yield for 45-keV Ar+ irradiation of amorphous
silicon is found to be in very good agreement with theory. In connection with earlier reported yields measured relative to those of argon, we here report absolute yields for 16 different ions (7 I Z, C 83). In no case does the difference between theory and experiment amount to more than 15 ‘A. The energy dependence of lead sputtering yield on silicon (25 keV I E i 500 keV) is also reported and found to agree with theory. (Denmark) H H Andersen and H L Bay, J Appl Phys, 46 (5), 1975, 1919-1921.
L Tommasino
33. GENERAL
et al, J Appl Phys, 46 (4), 1975, 1484-1488.
PHYSICS
AND ELECTRONICS
33 1304. Ion beam profile monitor. (USA) An ion beam profile monitor, which consists of a two-dimensional array of sample points placed in the beam, is described. The monitor provides an accurate and unambiguous display of the beam profile on a laboratory oscilloscope. Performance of the monitor under various ion beam conditions is presented. E P EerNisse et al, Rev Sri Instrum, 46 (3), 1975, 266268. 1305. Electron beam current controller for LEED-Auger
33 studies. (GB)
A control circuit is described which maintains a constant incident beam current for LEED-Auger electron guns. Significant in the design are isolation of control circuitry and gun by means of a solid state optical coupler, control based on true beam current, and adaptability of circuit to existing equipment. Control to better than 0.5 % is possible for beam currents between 0.1-100 pA. M Baines te al, J Phys E: Scient Znstrum, 8 (4), 1975, 305-307. 33 1306. The production of focused ion beams for surface and gas-phase collision studies. (GB)
Factors limiting the performance of practical ion beam systems are discussed and include momentum dispersion, instabilities, spacecharge repulsion and extraction optics. An approach to overall design is illustrated by an accelerator system employing low energy extraction and used for a range of working conditions and ion species. R E Hurley, Vacuum, 25 (4), 1975, 143-149. 33 1307. Molecular beam scattering from solid surfaces. (Germany)
Scattering of thermal atoms and molecules on solid surfaces has become an important and interesting field in surface physics. In this paper the most recent results of several groups are presented which were reported on the 2nd ICSS from 25-29 March 1974 in Kyoto. H Wilsch, Vacuum-Tech,
24 (2), 1975, 43-52 (in German).
1308. Scattering of helium and deuterium from single-crystal compared from two different laboratories. (USA)
32. NUCLEONICS 32 1302. The measurement
dioxide detectors. The detectors offer immediate information on the magnitude of particle fluxes and may possibly serve to identify the particles. (Italy)
of the radial ion temperature
distribution
in a
low-density plasma.
Density and temperature profiles (for both ions and electrons) and plasma rotation measurements are required for a detailed comparison between the properties of collisionless drift waves obtained with hydrogen plasma on the ODE experiment and the linear theory. Whenever these quantities cannot be measured by the simple electrostatic probe technique it is necessary to turn to spectroscopic techniques. Such a technique has been used here, and very accurate measurements of the Doppler broadening of the Hb line at 4862 A (H atoms being heated by charge exchange) give the ion temperature radial profiles for different experimental conditions in a low-density plasma (n = log-10”’ cmm3, T, = 13 eV, T, = 1 eV, and B. = l-3 kG). The improved spectroscopic system used is sufficiently sensitive for the plasma rotation to be measured where the azimuthal velocity is 10 times lower than the ion thermal velocity. This observation confirms the existence of a radial electric field E(r) in the plasma. The measurement of the rotation enables the frequency shifts of the unstable oscillations occurring in the laboratory frame to be investigated and an observed flute-type instability to be attributed to the centrifugal force arising from this E x B drift motion. (France) L A Hafez et al, JPhyJ D: Appl Phys, 8 (4), 1975, 374382. 32 1303. Thin-film breakdown counter of fission fragments.
(USA) A new kind of detector of heavy fission fragments is described. The detector is a thin-film capacitor in which electrical breakdowns are nonshorting. The detection is based on the counting of breakdowns which arise when heavy fission fragments hit the capacitor. These breakdowns occur at fields distinctly lower than those due to the application of the field only. The lowering of the breakdown field is discussed considering the thermal or electronic effects for silicon
33 Pt(ll1)
The angular distributions of scattered beams of helium and deuterium from platinum (I 11) surfaces which are obtained by two different laboratories using different techniques are compared. A basis for quantitative comparison of such inter-laboratory results is proposed. (Alp) S L Bernasek et al, J Vat Sci Technol, 12 (2), 1975, 655-657. 33 1309. The assignment of ion currents detected in the mass spectrum of a molecular beam. (GB)
A technique for assigning ion currents detected in the mass spectra of molecular beams is described with reference to the particular case of a molecular beam generated from a Knudsen effusion oven containing InP. Areas where the technique would find application are suggested. R F C Farrow, J Phys D: Appl Phys, 8 (4), 1975, L48-L52. 33 1310. Surface analysis with heavy ion induced Auger electrons; basic properties of a new method for materials sciences. (GB) Heavy ion induced Auger electron spectroscopy is presented as a new tool for surface analysis. In contrast to conventional Auger electron spectroscopy using electron excitation, the new technique offers the advantage of selective excitation of specific impurity elements present in a solid matrix by choosing a proper value of projectile mass and projectile energy. The technique is characterized by very fast rising cross-sections at threshold. The cross-sections can be very large in comparison to electron excitation. Due to the high energy loss of heavy ions at the energies applied, the projectiles are probing a very thin surface layer of the sample. Another benefit of heavy ion excitation is the possibility of simultaneous detection of back scattered heavy ions as well as the possibility for detection of ultra soft X-rays. In this way three complementary techniques are available simultaneously for mutual comparison. (Germany) K 0 Groeneveld et al, Vacuum, 25 (l), 1975,9-12. 459