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  • 1995-1999  (30)
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 1173-1175 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new-concept plasma grid, named frame-cooling-type plasma grid, was developed for a long pulse operation of a cesium-seeded volume H− ion source. The frame-cooling-type plasma grid was tested using a long pulse H− ion source. The grid has a kind of bellows structure that acts as thermal insulator to keep the surface temperature at an optimum value for H− ion production. It was confirmed that the temperature was kept at over 250 °C, an optimum temperature for the cesium effect, in steady-state operations with the plasma grid cooled by room-temperature water. Using the plasma grid, a maximum H− ion beam of 40 keV, 600 mA (16 mA/cm2) for a long pulse operation of 90 s was generated successfully. © 1998 American Institute of Physics.
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 1051-1053 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A high brightness negative hydrogen ion source has been developed for a high intensity proton linear accelerator. The ion source is volume production type. Negative ions are generated in a magnetically filtered multicusp plasma generator. The negative ion production is enhanced by seeding a small amount of cesium into the plasma generator. A negative hydrogen ion beam of 36 mA was extracted from a single aperture at an acceleration voltage of 50 kV. To obtain a higher ion beam current, the focusing of beamlets extracted from the multiaperture grid has been demonstrated with an aperture displacement technique. © 1996 American Institute of Physics.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 3859-3863 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The high power ion beams used in the next generation thermonuclear fusion reactors require high current negative ion beams accelerated to high energy, with high efficiency. One way to meet these requirements is to merge multiple low current density H− beamlets into a single high current beam. The feasibility of a high current merging preaccelerator was demonstrated in this experiment by merging 19 beamlets of H− ions distributed over a circular area 80 mm in diameter from a Japan Atomic Energy Research Institute negative ion source. H− ions were extracted at a current density exceeding 10 mA/cm2 at the ion source which operates at 0.13 Pa (1 mTorr), with a low arc power density (70 V×250 A). Spherically curved grids (with built-in magnetic electron suppression) were used in the preaccelerator to focus the extracted beamlets into a single 104 mA, 100 keV beam. The merged beam has a diameter of 23 mm and a converging angle of ±30 mrad at the beam envelope. The rms emittance of the 104 mA merging beam was 1.00 π mrad cm, which is a condition acceptable to the electrostatic quadropole accelerator for further acceleration. © 1995 American Institute of Physics.
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  • 4
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Neutral beams for the next generation tokamaks will be based on multiampere negative ion beams with a beam energy of about 1.0 MeV and pulse lengths of a thousand seconds. High intensity dc beams at these levels of beam energy will require extensive development in electrostatic accelerators. At Lawrence Berkeley Laboratory, a two-module electrostatic quadrupole (ESQ) accelerator was built to accelerate ions to 200 keV. In this experiment, up to 100 mA of H− beam current was obtained from a Japan Atomic Energy Research Institute cesiated volume source using a multiaperture preaccelerator which merged 19 beamlets into a single circular beam at the entrance to the ESQ accelerator. The H− beam was accelerated by the ESQ to accelerate 200 keV without any significant beam loss or emittance growth. © 1995 American Institute of Physics.
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 947-949 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Grid power loading in a multistage, multigrid accelerator was calorimetrically measured using the Japan Atomic Energy Institute 400 keV accelerator. This is the first result on the grid power loading in the multistage accelerator. It is turned out that the extracted electrons are effectively suppressed in an extractor. The leakage of the electrons extracted from the source plasma to the first acceleration grid, the second grid and the grounded grid were no more than 0.8%, 0.2%, and nearly zero of the extracted electron current, respectively. Under the optimum beam optics that gives the lowest beam divergence, the power loadings of the acceleration grids were dominated by acceleration of the stripped electrons. At a typical source operating pressure of 0.3 Pa, the power loadings of a first acceleration grid, a second acceleration grid, and a grounder grid were 3.4%, 5.0%, and 2.8% of the total beam power, respectively. From the comparison with the calculated grid power loading, it is found that the stripped electrons can be intercepted by intermediate acceleration grids before fully accelerated. © 1998 American Institute of Physics.
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  • 6
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The first results of the performance test of the large negative ion source for a JT-60U negative-ion-based neutral beam injector (N-NBI) are presented. The ion source consists of a cesium seeded multicusp plasma generator, where negative ions are produced via volume and surface processes, a 110 cm×45 cm multiaperture extractor, and a three-stage electrostatic accelerator. After negative ion production and voltage holding tests in test stands, the ion source was installed in the N-NBI system and the full power test began. Up to now, the ion source has produced 400 keV, 5.9 A (2.4 MW) D− ion beams, the world highest D− current and beam power, with a pulse duration of 0.1 s. © 1996 American Institute of Physics.
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  • 7
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The acceleration grid heat load was measured for the first time as a function of the bias voltage, with the source filling gas pressure using a 400 keV three-stage electrostatic accelerator with multi-aperture. The bias voltage dependence shows that leakage of electrons extracted with H− ions to an accelerator is suppressed efficiently in the extractor. The heat load is mainly due to electrons stripped from H− ions at a high source pressure. The heat load due to the stripped electrons could be suppressed effectively by reducing the source pressure. It was confirmed experimentally that reduction of the source pressure is important to suppress the electron acceleration. © 1996 American Institute of Physics.
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  • 8
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Technologies producing high power negative ion beams have been highly developed over the years at Japan Atomic Energy Research Institute for use in neutral beam injectors for heating the thermonuclear fusion plasmas. At present, it is possible to produce multiampere H−/D− ion beams quasicontinuously at energies of more than a few hundred keV with a good beam optics of beamlet divergence of a few mrad. Based on these technologies, two research and development projects have been initiated; one is to develop a 22 A/500 keV/10 s D− ion source for the neutral beam injector for JT-60U, and the other is to develop a 1 A/1 MeV/60 s H− ion source to demonstrate high current negative ion acceleration up to the energy of 1 MeV, the energy required for the neutral beam injector for the International Thermonuclear Experimental Reactor. © 1996 American Institute of Physics.
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  • 9
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Neutral beam injection has been the most successful scheme used to heat magnetically confined plasmas studied in controlled nuclear fusion research, and neutral beams are a candidate to heat to ignition the International Tokamak Experimental Reactor (ITER). This article describes the system which is presently being designed in Europe, Japan, and Russia, with coordination by the Joint Central Team of ITER at Naka, Japan. The proposed system consists of three negative ion based neutral injectors, delivering a total of 50 MW of 1 MeV D0 to the ITER plasma for pulse length of (approximately-greater-than)1000 s. The proposed injectors each use a single caesiated volume arc discharge negative ion source, and a multigrid, multiaperture accelerator, to produce about 40 A of 1 MeV D−. This will be neutralized in a subdivided gas neutralizer, which has a conversion efficiency of about 60%. The charged fraction of the beam emerging from the neutralizer is dumped onto the water-cooled surfaces making up the electrostatic residual ion dump. A water-cooled calorimeter can be moved into the beam path to intercept the neutral beam, allowing commissioning of the injector independent of ITER. © 1996 American Institute of Physics.
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  • 10
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the present study, the distribution pattern and characteristics of cells containing Factor XIII subunita (FXIII A) have been studied in benign and malignant lesions of human buccal mucosa. Tissues from four irritation fibromas and three squamous cell carcinomas were studied by means of double immunofluorescent staining techniques in which the detection of FXIII A was combined with a reaction with CD14 (recognizing a monocyte/macrophage differentiation marker antigen), Mac 387 (reacting with a special subset of macrophages), anti-HLA-DR, Ki-M7 (labelling phagocytosing macrophages) or Ki-67 (visualizing a nuclear antigen associated with cell proliferation) monoclonal antibodies. FXIII A was detected in cells of the connective tissue stroma in both benign and malignant buccal lesions. The number of these FXIII A-reactive cells (FXIII A+ cells) increased considerably in the tumour tissues, in particular in those surrounding tumour cell clusters. FXIII A+ cells scattered in the fibromatous tissues were spindle-shaped, whereas in the tumour stroma, large stellate cells predominated, and round cells were likewise labelled around blood vessels. FXIII A+ cells were labelled with CD14 and Ki-M7 in both fibromatous and tumoural buccal mucosa; however, they failed to show any reaction with Ki-67. FXIII A+ cells accumulated in the tumour stroma reacted for HLA-DR as well. These results indicate that in both the benign and malignant buccal lesions FXIII A is contained in a subpopulation of tissue macrophages, which represents a monocyte-derived (CD14+) and phagocytosing (KiM7+) cell population. The accumulation of the FXIII A+ cells in the tumour stroma is believed to be a result of direct migration from the circulating blood. The FXIII A+ cells of the tumour stroma may be actively involved in both antigen presentation and matrix remodelling during tumour progression.
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