Since the initial operation of the JET ICRF system in 1985, up to 22 MW has been coupled to the plasma, many heating scenarios have been demonstrated and the main technological problem of RF-specific impurity producti...
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Since the initial operation of the JET ICRF system in 1985, up to 22 MW has been coupled to the plasma, many heating scenarios have been demonstrated and the main technological problem of RF-specific impurity production overcome. Many developments of the antennae have taken place over this period, notably the replacement of the water-cooled nickel screens with indirectly cooled beryllium screens, and the forthcoming installation of eight new A2 antennae for operation during the pumped divertor phase of JET. The A2 antennae include enhanced provision for fast wave current drive experiments on JET. This paper describes the beryllium screens, the technological results from operation and subsequent inspection of these screens, the design of the A2 antennae and the results from high power RF testing of a model of the A2 antenna.
The design of polarization insensitive optical coatings via use of the needle synthesis algorithm in combination with second order optimization methods is explored. Several designs produced with this technique are pre...
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ISBN:
(纸本)0819415863
The design of polarization insensitive optical coatings via use of the needle synthesis algorithm in combination with second order optimization methods is explored. Several designs produced with this technique are presented and comparisons are made with the results of other design techniques drawn from the literature.
The concepts and current status of Japanese 8.2 m optical and IR telescope project, SUBARU, are summarized. SUBARU aims to achieve imaging with very high resolution of 0.2 - 0.1 arc sec, and high observing capability ...
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ISBN:
(纸本)0819414948
The concepts and current status of Japanese 8.2 m optical and IR telescope project, SUBARU, are summarized. SUBARU aims to achieve imaging with very high resolution of 0.2 - 0.1 arc sec, and high observing capability through the wide wavelength region of optical and near-IR. The construction of SUBARU has started in 1991. So far the 8.3 m mirror blank was successfully formed, the construction of the lower fixed part of the enclosure is almost finished, and the main parts of the telescope are being fabricated. The first light of SUBARU is scheduled to be 1998 spring.
The rotational part of the enclosure of SUBARU telescope (Japan National Large Telescope, or JNLT) is under the fabrication in Canada, and on-site erection is scheduled to take place in May, 1994, with the expected co...
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ISBN:
(纸本)0819414948
The rotational part of the enclosure of SUBARU telescope (Japan National Large Telescope, or JNLT) is under the fabrication in Canada, and on-site erection is scheduled to take place in May, 1994, with the expected completion in the third quarter of 1995. The enclosure is featured with various design consideration for a better seeing performance, a better wind buffet performance, and good operability and maintainability. This paper describes the major design consideration behind the final shape and function of the enclosure and the current status of its fabrication.
作者：
BOSKE, LBUNIV TEXAS
LYNDON B JOHNSON SCH PUBL AFFAIRSUNIV STNAUSTINTX 78713
This presentation highlights the results of a recently completed study that examines the Texas-Mexico multimodal transport system already in place, current plans for improvements or expansion, and opportunities and co...
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ISBN:
(纸本)0819413879
This presentation highlights the results of a recently completed study that examines the Texas-Mexico multimodal transport system already in place, current plans for improvements or expansion, and opportunities and constraints faced by each transport mode - motor carriage, rail, maritime, and air. Particular emphasis is given to findings regarding transportation developments in Mexico. The study concludes that in Mexico, all modes are working at establishing new services and strategic alliances, intermodal arrangements are on the rise, and private-sector participation in infrastructure improvements is growing daily at Mexican seaports and airports as well as within that nation's highway and rail systems. This presentation looks at developments that concern privatization, deregulation, infrastructure improvements, financing arrangements, and new services in Mexico.
A current status and perspectives of the work on a high density polarized 3He target are reported. The problems of high-power laser design for optical pumping are discussed. A general formulation for the analysis of a...
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ISBN:
(纸本)0819413747
A current status and perspectives of the work on a high density polarized 3He target are reported. The problems of high-power laser design for optical pumping are discussed. A general formulation for the analysis of an arbitrary linear resonator with internal lens of variable focal length, which represents the rod of a solid-state laser is presented. It is shown that mode spot size is stable with respect to lens optical power fluctuations in one part of resonator when it reaches a minimum on a laser rod. The rules for the design of stable resonators with two or more variable lenses are proposed.
The achieved pointing and tracking performance of the telescope is presented and compared with the Keck goals. The implications of the current performance on observing are discussed, and planned remedies for deficienc...
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ISBN:
(纸本)0819414948
The achieved pointing and tracking performance of the telescope is presented and compared with the Keck goals. The implications of the current performance on observing are discussed, and planned remedies for deficiencies in pointing and tracking are proposed.
The macroscopic hidden logic in the evolution of astronomical telescopes, from the days of Galileo, points towards a cylindrical horse shoe design, resembling the fork. This design has the advantages of both equatoria...
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ISBN:
(纸本)0819414948
The macroscopic hidden logic in the evolution of astronomical telescopes, from the days of Galileo, points towards a cylindrical horse shoe design, resembling the fork. This design has the advantages of both equatorial as well as altazimuth mounts; but it inherits pointing problems inherent in the current logic of evolution. Whereas the orientation-analysis of stellar objects reveals that in spite of: (1) the lateral shift of the telescope due to spinning and two orbital motions of the earth and (2) the `big-bang expansion' of the universe, we can refer multi stellar objects simultaneously for error free offset tracking. The emerging fundamental logic demands no references to earth which is seen as a rattling platform and hence it circumvents the pointing problems caused by gravity, wind, ground noises, atmospheric refraction, wobbling of earth, etc. The resulting new concept telescope has the following features: (1) It is floated on multi layer air cushions; (2) two bright stars are used for auto guiding; (3) the central shadowed portion of the primary mirror is utilized as the reflector of guide field; (4) telescope shape is spherical; (5) tube is of classical Serrurier strut design and (6) four to eight folded Cassegrain stations are located around the primary mirror.
As the power and the frequency of a relativistic klystron increase, design of both modulation and extraction cavities becomes increasingly difficult. If the gap is narrow, the rf electric field begins to exceed limits...
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ISBN:
(纸本)0819414492
As the power and the frequency of a relativistic klystron increase, design of both modulation and extraction cavities becomes increasingly difficult. If the gap is narrow, the rf electric field begins to exceed limits for electron emission or breakdown. On the other hand, if the gap width exceeds a small fraction of a wavelength, typical extraction modes do not couple well, and space charge potential energy reduces efficiency and limits the current that can cross the gap. We present theoretical investigations of a novel gap design that incorporates an inductively loaded return-current structure. This structure serves to neutralize the dc space charge of the beam, while sustaining the longitudinal rf field that extracts the microwave energy. With appropriate choice of resonant modes, it appears that gap widths exceeding a half wavelength can be used for modulation of high-current beams, as well as extraction of rf energy with high efficiency.
The output characteristics of a strip distributed microwave (MW) power amplifier tuned by voltage in a wide frequency range analyzed. New energy collector designs are proposed to be employed in the amplifier in the fo...
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ISBN:
(纸本)0819415154
The output characteristics of a strip distributed microwave (MW) power amplifier tuned by voltage in a wide frequency range analyzed. New energy collector designs are proposed to be employed in the amplifier in the form of a periodically nonuniform strip line and electron optical system comprising an electron gun with the multi-edge field emitter array current modulator. Their electrodynamic and current parameters have been calculated by rigorous methods. The analysis of the output amplitude-frequency characteristics of the amplifier was performed. It is shown that, unlike the previously reported amplifier design, it can allow for a higher gain in the short-wavelength region of centimeter band, including the millimeter band, or operate at substantially lower beam currents.
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