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  • 1
    Electronic Resource
    Electronic Resource
    Particle reflection and TFTR neutral beam diagnostics : Proceedings of the 9th topical conference on high temperature plasma diagnostics (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 4523-4526 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Determination of two critical neutral beam parameters, power and divergence, are affected by the reflection of a fraction of the incident energy from the surface of the measuring calorimeter. On the TFTR Neutral Beam Test Stand, greater than 30% of the incident power directed at the target chamber calorimeter was unaccounted for. Most of this loss is believed due to reflection from the surface of the flat calorimeter, which was struck at a near grazing incidence (12°). Beamline calorimeters, of a "V''-shape design, while retaining the beam power, also suffer from reflection effects. Reflection, in this latter case, artificially peaks the power toward the apex of the "V,'' complicating the fitting technique, and increasing the power density on axis by 10%–20%; an effect of import to future beamline designers. Agreement is found between measured and expected divergence values, even with 24% of the incident energy reflected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143709
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  • 2
    Electronic Resource
    Electronic Resource
    Observation of Doppler shifted Tα emission from TFTR tritium neutral beams : Proceedings of the tenth topical conference on high temperature plasma diagnostics (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 632-634 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: 195 tritium ion source shots were injected into Tokamak Fusion Test Reactor (TFTR) high power plasmas during December 1993–March 1994. In addition, four highly diagnosed pulses were fired into the calorimeter. Analysis of the Doppler shifted Tα emission of the beam in the neutralizer has revealed that the extracted ion compositions for deuterium and tritium are indistinguishable: 0.72±0.04 D+; 0.22±0.02 D+2; 0.07±0.01 D+3 compared to 0.72±0.04 T+; 0.23±0.02 T+2; 0.05±0.01 T+3. The resultant tritium full-energy neutral fraction is higher than for deuterium due to the increased neutralization efficiency at lower velocity. To conserve tritium, it was used only for injection and a few calorimeter test shots, never for ion source conditioning. When used, the gas species were switched to tritium only for the shot in question. This resulted in an approximately 2% deuterium contamination of the tritium beam and vice versa for the first deuterium pulse following tritium. Data from the calorimeter shots indicate that tritium contamination of the deuterium beam cleans up in five to six beam pulses, and is reduced to immeasurable quantities prior to deuterium beam injection. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1146309
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  • 3
    Electronic Resource
    Electronic Resource
    Low Z impurity ion extraction from Tokamak Fusion Test Reactor ion sources (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 2729-2736 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Tokamak Fusion Test Reactor (TFTR) deuterium neutral beams have been operated unintentionally with significant quantities of extracted water ions. Water has been observed with an optical multichannel analyzer. These leaks were thermally induced with the contamination level increasing linearly with pulse length. Up to 6% of the beam current was attributed to water ions, corresponding to an instantaneous value of 12% at the end of a 1.5 s pulse. A similar contamination is observed during initial operation of ion sources exposed to air. Operation of new ion sources typically produces a contamination level of ∼2%, with cleanup to undetectable levels in 50–100 beam pulses. Approximately 90% of the water extracted from ion sources with water leaks was deuterated, implying that there is the potential for tritiated water production during TFTR's forthcoming DT operation. It is concluded that isotope exchange in the plasma generator takes place rapidly, most likely as the result of surface catalysis. The primary concern is with O implanted into beam absorbers recombining with tritium, and the subsequent retention of T2O on cryopanels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144411
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  • 4
    Electronic Resource
    Electronic Resource
    Measurement of thermal ion profiles in TFTR neutral beamlines (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 3701-3709 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A technique is described whereby the ion dumps inside the TFTR Neutral Beam Test Stand were used to measure thermal profiles of the full-, half-, and third-energy ions. 136 thermocouples were installed on the full-energy ion dump, allowing full beam contours. Additional linear arrays across the widths of the half- and third-energy ion dumps provided a measure of the shape, in the direction parallel to the grid rails, of the half- and third-energy ions, and, hence, of the molecular ions extracted from the source. As a result of these measurements, it was found that the magnet was more weakly focusing, by a factor of 2, than expected, explaining past overheating of the full-energy ion dump. Hollow profiles on the half- and third-energy ion dumps were observed, suggesting that extraction of D+2 and D+3 is primarily from the edge of the ion source. If extraction of half-energy ions is from the edge of the accelerator, a divergence parallel to the grid rails of 0.6°±0.1° is deduced. It is postulated that a nonuniform gas profile near the accelerator is the cause of the hollow partial-energy ion profiles, the pressure being depressed over the accelerator by particles passing through this highly transparent structure. Primary electrons reaching the accelerator produce nonuniform densities of D+2 through the ionization of this gas. D+3 is created through subsequent D+2-gas collisions. A technique of rastering the ion beam across the full-energy dump was examined as a means of reducing the power density. By unbalancing the currents in the two coils of the magnet, on a shot-by-shot basis, by up to a 2:1 ratio, it was possible to move the centerline of the full-energy ion beam sideways by ∼12.5 cm. The adoption of such a technique, with a ramp of the coil imbalance from 2:1 to 1:2 over a beam pulse, could reduce the full-energy ion dump power density by a factor of (approximately-greater-than)1.5.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143601
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  • 5
    Electronic Resource
    Electronic Resource
    Early pregnancy termination: a comparison between vacuum aspiration and medical abortion using prostaglandin (16,16 dimethyl-trans-Δ2-PGE1 methyl ester) or the antiprogestogen RU 486 (1988)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 95 (1988), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1988.tb06561.x
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  • 6
    Electronic Resource
    Electronic Resource
    ABDOMINAL STERILIZATION USING THE PROCTOSCOPE (1971)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 78 (1971), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In a series of 50 cases a proctoscope was inserted suprapubically into the peritoneal cavity and the Fallopian tubes ligated under direct vision. The short incision and the use of an absorbable subcuticular suture allowed the patients to leave hospital 48 hours after operation. The method is quick and easy, and peritoneal insufflation is avoided.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1971.tb00268.x
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  • 7
    Electronic Resource
    Electronic Resource
    Temporal behavior of neutral particle fluxes in TFTR neutral beam injectors (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 3721-3729 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Data from an E(parallel)B charge exchange neutral analyzer (CENA), which views down the axis of a neutral beamline through an aperture in the target chamber calorimeter of the TFTR neutral beam test facility, exhibit two curious effects. First, there is a turn-on transient lasting tens of milliseconds having a magnitude up to three times that of the steady state level. Second, there is a 720 Hz, up to 20% peak-to-peak fluctuation persisting the entire pulse duration. The turn-on transient occurs as the neutralizer/ion source system reaches a new pressure equilibrium following the effective ion source gas throughput reduction by particle removal as ion beam. Widths of the transient are a function of the gas throughput into the ion source, decreasing as the gas supply rate is reduced. Heating of the neutralizer gas by the beam is assumed responsible, with gas temperature increasing as gas supply rate is decreased. At low gas supply rates, the transient is primarily due to dynamic changes in the neutralizer line density and/or beam species composition. Light emission from the drift duct corroborate the CENA data. At high gas supply rates, dynamic changes in component divergence and/or spatial profiles of the source plasma are necessary to explain the observations. The 720 Hz fluctuation is attributed to a 3% peak-to-peak ripple of 720 Hz on the arc power supply amplified by the quadratic relationship between beam divergence and beam current. Tight collimation by CENA apertures cause it to accept a very small part of the ion source's velocity space, producing a signal linearly proportional to beam divergence. Estimated fluctuations in the peak power density delivered to the plasma under these conditions are a modest 3%–8% peak to peak. The effects of both phenomena on the injected neutral beam can be ameliorated by careful operation of the ion sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140482
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  • 8
    Electronic Resource
    Electronic Resource
    Doppler-shifted neutral beam line shape and beam transmission (1995)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 130-138 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Analysis of Doppler-shifted Balmer-α line emission from the Tokamak Fusion Test Reactor's (TFTR) neutral beam injection systems has revealed that the line shape, which is a direct measure of the velocity distribution function, is well approximated by the sum of two Gaussians, or, alternatively, by a Lorentzian. For the sum of two Gaussians, the wide-divergence part of the distribution contains 40% of the beam power and has a divergence five times that of the narrow part. Assuming a narrow 1/e-divergence of 1.3° (based on fits to the beam shape on the calorimeter), the wide part has a divergence of 6.9°. The entire line shape is also well approximated by a Lorentzian with a half-maximum divergence of 0.9°. Up to now, most fusion neutral beam modelers have assumed a single Gaussian velocity distribution, at the extraction plane, in each direction perpendicular to beam propagation. This predicts a beam transmission efficiency from the ion source to the calorimeter of 97%. Waterflow calorimetry data, however, yield a transmission efficiency of ∼75%, a value in rough agreement with predictions of the two Gaussian or Lorentzian models presented here. The broad wing of the two Gaussian distribution also accurately predicts the loss in the neutralizer. An additional factor in determining the power density at the surface of beam absorbers is the angle at which the particles arrive. Angles are different for particles emitted from different locations on the ion source. To treat this situation, the average angle of incidence is calculated. For beam loss at the exit of the neutralizer, the average angle of incidence is 2.2°, rather than the 4.95° subtended by the center of the ion source. This average angle of incidence is found to be a function of beam divergence. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1145277
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  • 9
    Electronic Resource
    Electronic Resource
    Experiments with high-voltage insulators in the presence of tritium (1991)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 376-380 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: During the final deuterium-tritium phases of the TFTR and JET tokamaks half of the neutral injectors will be used to produce tritium neutral beams to maintain an equal mix of deuterium and tritium in the core plasma, and such requirements may also occur in future devices. This will require that the voltage hold off capabilities of the high voltage insulators in the accelerators be unimpaired by any charge buildups associated with the beta decay of adsorbed layers. We report tests in which we measured the drain currents under high dc voltage of TFTR and JET accelerator insulators while they were successively exposed to vacuum, deuterium and tritium. There did not appear to be any substantial reduction in hold-off capability with tritium, although at some voltages there was a small increase in the leakage current. We also compared the breakdown properties of a plastic tubing filled with deuterium and then tritium at varying pressures, since such tubing has been considered as a high-voltage break in the gas feed system for TFTR, and the presence of large numbers of electron-ion pairs might lead to enhanced Paschen breakdown. We found no significant differences in the behavior for the geometry used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142131
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  • 10
    Electronic Resource
    Electronic Resource
    TFTR neutral beam injected power measurement (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 3377-3385 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Energy flow within TFTR neutral beamlines is measured with a waterflow calorimetry system capable of simultaneously measuring the energy deposited within four heating beamlines (three ion sources each), or of measuring the energy deposited in a separate neutral beam test stand. Of the energy extracted from the ion source on the well-instrumented test stand, 99.5±3.5% can be accounted for. When the ion deflection magnet is energized, however, 6.5% of the extracted energy is lost. This loss is attributed to a spray of devious particles onto unmonitored surfaces. A 30% discrepancy is also observed between energy measurements on the internal beamline calorimeter and energy measurements on a calorimeter located in the test stand target chamber. Particle reflection from the flat plate calorimeter in the target chamber, which the incident beam strikes at a near-grazing angle of 12°, is the primary loss of this energy. A slight improvement in energy accountability is observed as the beam pulse length is increased. This improvement is attributed to systematic error in the sensitivity of the energy measurement to small fluctuations in the supply water temperature. An overall accuracy of 15% is estimated for the total power injected into TFTR. Contributions to this error are uncertainties in the beam neutralization efficiency, reionization and beam scrape-off in the drift duct, and fluctuations in the temperature of the supply water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140533
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