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  • 2000-2004  (8)
  • 1
    Electronic Resource
    Electronic Resource
    Numerical simulation of cesium cooling effects in H− ion source : The 8th international conference on ion sources (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 880-882 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Cesium volume reactions are included in a two-point model numerical code for a high power hydrogen negative ion source. The energy balance equation for the electron temperature and rate equations of Cs and Cs+ are included in our code to investigate the electron cooling and volume effects by cesium seeding. Cesium density in the ion source is taken as a variable for the calculation. Cesium is ionized over 95% in the driver region of the ion source. The electron temperature begins to decrease at cesium density 1011 cm−3 and the electron density increases because of the ionization of cesium. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150320
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  • 2
    Electronic Resource
    Electronic Resource
    Monte Carlo simulation of negative ion production in the negative hydrogen ion source : The 8th international conference on ion sources (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 883-886 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two Monte Carlo simulation codes: (a) neutral transport code and (b) negative ion (H−) transport code, have been developed to understand transport phenomena in negative ion sources. In the neutral transport code, Boltzmann equations for hydrogen molecules (H2) and atoms (H) are solved. Three dimensional (3D) spatial distributions of H2, H, and H− production are obtained for a tandem negative ion source. The volume production of H− is limited to the area around the gas inlet in the first chamber and near the plasma grid in the second chamber. On the other hand, distribution of H− surface production is shown to be almost uniform over all the plasma grid surface. In the negative ion code, H− trajectories are calculated by numerically solving the 3D equation of motion for H− ions. The effects of the magnetic filter on the extraction probability of surface produced H− ions are mainly studied. The dependence of the extraction probability on the field strength is small. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150321
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  • 3
    Electronic Resource
    Electronic Resource
    Negative hydrogen ion source for TOKAMAK neutral beam injector (invited) : The 8th international conference on ion sources (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 1219-1224 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Intense negative ion source producing multimegawatt hydrogen/deuterium negative ion beams has been developed for the neutral beam injector (NBI) in TOKAMAK thermonuclear fusion machines. Negative ions are produced in a cesium seeded multi-cusp plasma generator via volume and surface processes, and accelerated with a multistage electrostatic accelerator. The negative ion source for JT-60U has produced 18.5 A/360 keV (6.7 MW) H− and 14.3 A/380 keV (5.4 MW) D− ion beams at average current densities of 11 mA/cm2 (H−) and 8.5 mA/cm2 (D−). A high energy negative ion source has been developed for the next generation TOKAMAK such as the International Thermonuclear Experimental Reactor (ITER). The source has demonstrated to accelerate negative ions up to 1 MeV, the energy required for ITER. Higher negative ion current density of more than 20 mA/cm2 was obtained in the ITER concept sources. It was confirmed that the consumption rate of cesium is small enough to operate the source for a half year in ITER-NBI without maintenance. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150432
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  • 4
    Electronic Resource
    Electronic Resource
    Hydrogen negative ion beam acceleration in a multiaperture five-stage electrostatic accelerator : The 8th international conference on ion sources (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 1231-1233 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: To develop a high power negative ion source/accelerator for 1 MeV class neutral beam injector, hydrogen negative ion beam acceleration has been studied using a five-stage, multiaperture electrostatic accelerator. After conditioning each accelerator stage, the negative ions are accelerated to 1 MeV successfully with a drain current of 25 mA for 1 s. Cs was introduced into the ion source to produce higher current density. The highenst acceleration current density of 15 mA/cm2 was successfully accelerated up to an energy of 700 keV for 1 s, keeping the optimum perveance. The total acceleration current of 200 mA was extracted from nine central apertures 14 mm diameter each. A preliminary measurement of the heat load in the accelerator showed that the direct interception of the beam for the first grid and the third grid was negligibly small. The highest heat load was 4.5% of the input power at the second grid. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150434
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  • 5
    Electronic Resource
    Electronic Resource
    Development of a large volume negative-ion source for ITER neutral beam injector : Papers from the Ninth International Conference on Ion Sources (2002)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 1090-1092 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Development of the negative-ion sources has been conducted to realize a high power neutral beam injector for International Thermonuclear Experimental Reactor (ITER). A high negative-ion current density of 31 mA/cm2 (H−) at a very low pressure of 0.1 Pa has been produced in a cesium seeded multicusp plasma generator which has the same concept of the ITER source. For a vacuum insulated accelerator, a voltage holding experiment of long distance vacuum gaps up to ∼1.8 m has been performed. It was clarified that the transition region of product pressure distance (pd) from the vacuum breakdown to the gas discharge is about 0.2 Pa m which is high enough from the operating region of the ITER source. A prototype vacuum insulated accelerator was fabricated based on the experiment and tested. A high-energy H− beam acceleration up to 970 keV, 37 mA, and 1 s has been successfully demonstrated. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1431422
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  • 6
    Electronic Resource
    Electronic Resource
    Optimization of plasma grid material in cesium-seeded volume negative-ion sources : Papers from the Ninth International Conference on Ion Sources (2002)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 964-966 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In cesium-seeded hydrogen negative-ion sources, surface production on the plasma grid plays an important role in negative ion production. To enhance the surface, it is required to use material that would give a lower work function when Cs is absorbed on the surface. In a semicylindrical and cesium-seeded volume negative-ion source, eight materials (W, Cu, Mo, V, Cr, Ni, Ag, and Au) were tested as candidates for the plasma grid material. To avoid deposition of the cathode material on these materials, a filament-free plasma source was used, to fire the microwave (2.45 GHz) discharge in the Kamaboko source. The material surface was examined by measuring the photoelectron current by laser irradiation. It was observed that the discharge enhanced the photoelectron current when the material was biased negatively to the plasma potential during discharge. In the present experiment, Ni, Au, and Ag surfaces with a Cs layer showed a higher photoelectron current than the others. This was 1.5 times larger than that of Cu and W used as a plasma grid and filament in conventional high current negative ion sources. It is expected that higher negative-ion production efficiency would be obtained by using Ni, Ag, and Au as the plasma grid material, if deposition of filament materials is avoided on the surface. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1428419
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  • 7
    Electronic Resource
    Electronic Resource
    Spatial uniformity of negative ion production in volume negative ion source : Papers from the Ninth International Conference on Ion Sources (2002)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 1064-1066 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A spatial uniformity of negative ion production has been studied experimentally in a tandem-type volume negative ion source, where the plasma is divided into two regions by a magnetic filter, i.e., a driver region and an extraction region near the plasma grid (PG). A plasma density profile and the negative ion beam profile were measured. By the Langmuir probe measurement, a strong nonuniformity of the plasma density was observed near the plasma grid when the plasma grid is biased electrically with respect to the anode. By changing the polarity of the bias voltage, the deviation of the plasma density profile changed to the direction of E×B. In the pure hydrogen operation, the extracted beam profile corresponded to the plasma density profile in the extraction region. In the Cs-seeded operation, on the other hand, the uniformity of the beam current density became uniform despite the nonuniformity of the plasma density profile in the extraction region. The uniformity of the negative ions corresponded to the plasma uniformity in the driver region. These results indicate that the negative ions are not produced by positive ions in the extraction region in the Cs-seeded operation. We conclude that the negative ions are produced mainly by neutral atoms produced in the driver region via the surface production on the PG. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1430527
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  • 8
    Electronic Resource
    Electronic Resource
    Stress and coping behavior in patients with diabetes mellitus (2000)
    Springer
    Acta diabetologica 37 (2000), S. 61-64 
    Details
    ISSN: 1432-5233
    Keywords: Key words Diabetes mellitus ; Coping scale ; Stress tolerance ; Diabetes education ; Stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Diabetes mellitus is a disease which must be controlled over the lifetime of a patient. We investigated the issues of stress and coping for diabetes mellitus which may influence self-management. In addition, we examined the association of these factors with blood glucose control, in order to review self-management instructions for diabetes mellitus. The study included 153 patients with diabetes mellitus. The patients were divided into two subgroups: good-control group, comprising patients with glycohemoglobin (HbA1c) values less than 7.0%; and poor-control group, comprising those with HbA1c values of 7.0% or more. All patients responded to a questionnaire regarding stress tolerance, Jalowiec and Power's coping scale and awareness of diabetes mellitus. Stress tolerance was not significantly different between the good-control and poor-control groups. No significant gender differences in coping score were evident for the good-control group. However, in the poor-control group, the coping score in men was significant higher than that in women. The problem-oriented coping score for men in the poor-control group was significantly higher than that for the good-control group (p 〈 0.01). In a comparison of awareness of diabetes mellitus, the proportion of patients who replied that they were rigidly following diabetes treatment was higher in the poor-control group than the good-control group. Patients with diabetes mellitus may have a knowledge of the disease and a strong will to resolve problems. This is especially true for male patients in that their will appeared to be stronger, but they may not have the resolve to establish appropriate behavior patterns. In the future, methods for evaluating self-management should be included in diabetes education.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005920070020
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