Showing papers on "Microchannel published in 1988"
Patent•
09 Mar 1988TL;DR: A microchannel heat sink as discussed by the authors is used to cool a high power electronic device such as an integrated circuit comprising a plurality of channels in close thermal contact to the integrated circuit and through which a liquid is passed to create either a developing laminar flow or a turbulent flow.
Abstract: A microchannel heat sink used to cool a high power electronic device such as an integrated circuit comprising a plurality of channels in close thermal contact to the integrated circuit and through which a liquid is passed to create either a developing laminar flow or a turbulent flow. The turbulent flow may be either developing or fully developed. The heat sink features a compensation heater surrounding the integrated circuit and heated at the same rate as the integrated circuit to thereby provide a more uniform temperature at the perimeter of the integrated circuit.
269 citations
01 Jan 1988
TL;DR: In this paper, microchannel heat sinks useful in the cooling of diode laser arrays have been fabricated from InP and exhibit a thermal resistance as low as 0072 C/(W/sq cm).
Abstract: Microchannel heat sinks useful in the cooling of diode laser arrays have been fabricated from InP and exhibit a thermal resistance as low as 0072 C/(W/sq cm), corresponding to the dissipation of heat loads in excess of 1 kW/sq cm and representing a two-orders-of-magnitude reduction of levels achievable by current methods The pumping power required to force liquid coolants through microchannel heat sinks can be kept as low as as 10 W/sq cm Attention is presently given to a thermal- and fluid-performance model for these heat sinks, as well as to illustrative examples of microchannel fabrication for both InP and aluminum 19 references
202 citations
TL;DR: Performance characteristics of several new types of photomultiplier tubes (PMT) with microchannel plates (MCP) are presented and the basic configuration, characteristics, and practical results are described.
Abstract: Performance characteristics of several new types of photomultiplier tubes (PMT) with microchannel plates (MCP) are presented in this paper. They are the MCP-PMT with 6-microm diam channels, MCP-PMT with an S-l photocathode, and MCP-PMT with multi (discrete) anode and gatable MCP-PMT. Important requirements of an optical detector for picosecond lasers, fluorescence measurements, and material analysis are low light detectability, ultrafast time response, and versatile operation including modulation. The basic configuration, characteristics, and practical results of these detectors are described.
133 citations
TL;DR: In this paper, a heat exchanger package for semiconductor laser arrays using silicon microstructures with water as the coolant has been demonstrated, achieving a thermal impedance of 0.04°C cm2/W for a single linear bar.
Abstract: A heat exchanger package has been demonstrated for semiconductor laser arrays using silicon microstructures with water as the coolant. A thermal impedance of 0.04 °C cm2/W has been achieved for a single linear bar. This design makes use of efficient, edge‐emitting laser diode arrays in a rack and stack architecture combined with a high‐performance silicon microchannel structure to allow cw operation. The architecture can be scaled to large areas and we project a thermal impedance of 0.09 °C cm2/W for close‐packed two‐dimensional arrays on this device.
102 citations
31 citations
Patent•
02 Jun 1988TL;DR: A tandem mass spectrometer includes an ion source, a first mass analyzer, a micro-channel collision plate, a second mass analyser, and a detector as mentioned in this paper, where the collision of parent ions with the internal surfaces of the micro-channels causes the parent ions to dissociate into daughter ions.
Abstract: A tandem mass spectrometer includes an ion source, a first mass analyzer, a microchannel collision plate, a second mass analyzer, and a detector. The microchannel collision plate comprises a matrix defining a plurality of microchannels which are disposed in a generally parallel orientation with a beam of parent ions emanating from the first mass analyzer. Collision of the parent ions with the internal surfaces of the microchannels causes the parent ions to dissociate into daughter ions. The second mass analyzer distinguishes between various mass fractions of the daughter ions, allowing the detector to quantitate said fractions and produce a mass spectra of the material being analyzed.
23 citations
15 Dec 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the conductive analogue charge division readout is described as typified by the Wedge and Strip Anode (WSA), used in conjunction with a microchannel pl A mathematical model has been used to evaluate the positional modulation produced by various spatial charge distributions on the WSA readout.
Abstract: We describe the conductive analogue charge division read-out as typified by the Wedge and Strip Anode (WSA), used in conjunction with a microchannel pl A mathematical model has been used to evaluate the positional modulation produced by various spatial charge distributions on the WSA readout. The spati Finally, we describe an application for a sealed intensifier comprising an optical/UV photocathode, a chevron pair of microchannel plates and a Tetra Wedge Anode which is presently under construction.
21 citations
TL;DR: In this article, the characteristics of microchannel plates (MCPs) for detection of x rays have been investigated using synchrotron radiation in the energy ranges from 0.6 to 2.0 keV and from 5 to 20 keV.
Abstract: The characteristics of microchannel plates (MCPs) for detection of x rays have been investigated using synchrotron radiation in the energy ranges from 0.6 to 2.0 keV and from 5 to 20 keV. Microchannel plates are operated under the condition of an unsaturated pulse‐height distribution mode. The current response curve of MCPs is measured continuously with x‐ray energy variation for the first time. The experimental result of some discontinuous jumps in the response is obtained at the energies corresponding to the absorption edge of the MCP materials. In the low‐energy range (hν 5 keV), a weak dependence on θ is observed, and is attributed mainly to the penetration of x rays through multiple channels.
19 citations
TL;DR: In this paper, a novel type of high-gain electron multiplier formed by bonding, in permanent contact, three standard (channel length-to-diameter ratio L/D=40:1) image-intensifier multichannel plates.
Abstract: A sandwich plate is a novel type of high-gain electron multiplier formed by bonding, in permanent contact, three standard (channel length-to-diameter ratio L/D=40:1) image-intensifier multichannel plates. This geometry has the advantage of mechanical and electrical simplicity when compared with conventional multiplate stacks. An evaluation of sandwich plates for X-ray photon counting is presented. Sandwich plate gain, gain uniformity, pulse height FWHM, dark noise, high-count-rate operation, and X-ray quantum efficiency are compared with previous measurements made with conventional two-stage MCP (microchannel plate) multipliers. >
19 citations
11 Jul 1988
TL;DR: In this paper, single and multi-frame gated x-ray images with time-resolution as fast as 150 psec are described, where the gating voltage comes from the avalanche breakdown of reverse biased p-n junction producing high power voltage pulses as short as 70 psec.
Abstract: Single and multi-frame gated x-ray images with time-resolution as fast as 150 psec are described. These systems are based on the gating of microchannel plates in a stripline configuration. The gating voltage comes from the avalanche breakdown of reverse biased p-n junction producing high power voltage pulses as short as 70 psec. Results from single and four frame x-ray cameras used on Nova are described. There has been much recent interest in gated x-ray cameras and spectrometers with gate times as short as 100 psec. In the ICF field, this time resolution is necessary to freeze implosions with velocities of 107 cm/s and resolutions of 10 μm. There are two different techniques for gating, shuttering electro optic tubes and voltage gating of a proximity focussed device. Several schemes have been proposed for subnanosecond shuttering of electro-optical tubes. Such approaches are attractive in that several frames can in principle, be achieved, there is little problem from x rays that are transmitted through the cathode, and a uniform response can be obtained over a large photocathode area. However, these schemes are complex and to date have found little practical application. Gating a proximity focused device is much simpler. A voltage pulse is applied across either photocathode-phosphor gap, or across a microchannel plate. There are several disadvantages to this approach: a fast, high voltage drive is required because a large detector area implies a high capacitance, it is inherently a single-frame device, straight through hard x rays can cause problems, and the response across a large sensitive area will be non-uniform due to the finite propagation velocity of the gating voltage wave. Until recently, fast high voltage pulses for the electrical gating could only be generated by photoconductive switches with the concomitant complexity of a short pulse laser. However, the well known phenomenon of avalanche breakdown/ has now been developed so that high power electrical pulses as short as 70 psec can be produced by purely electronic drivers. These voltage pulses are applied to a strip transmission line with a microchannel plate as the dielectric. The temporal and spatial resolution are described in Sec. II. Using a voltage doubling scheme sufficient voltage from four paralleled reverse biased diodes can be produced to gate four microchannel plates arranged in the four corners of a rectangle. The field uniformity and gain width variation of this configuration are described in Sec. II. For use on Nova, these microchannel plates are gated at different times and detect four gated images from an array of four pinholes. The system and its timing fiducial are described in Sec. III. Representative results from direct-drive implosions are described in Sec. IV.© (1988) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
18 citations
TL;DR: In this paper, an evaluation of the long-life (L/sup 2/) micro-channel plates (MCPs) operated in pulse counting mode is presented, and the measurements indicate that the Galileo MCPs, even those with short channel lengths, have desirable characteristics for photon counting applications.
Abstract: An evaluation is presented for Galileo long-life (L/sup 2/) microchannel plates (MCPs) operated in pulse counting mode. Modal gain, pulse height FWHM, gain uniformity, and high-count-rate performance data are compared with measurements made with MCPs of conventional glass composition. Despite the absence of potassium (and hence, of the beta -emitter /sup 40/ K) from the L/sup 2/ glass, dark count rates for the L/sup 2/ MCPs are about five-times higher than those of standard MCPs, due to the presence in the glass of the radioisotope /sup 87/Rb. The measurements indicate that Galileo L/sup 2/ MCPs, even those with short channel lengths, have several desirable characteristics for photon-counting applications. They also confirm that changing the radioisotope composition of channel plate glass influences the dark noise count rate, further supporting an internal radioactivity noise model developed by the authors. >
15 Jan 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the behavior of microchannel plate (MCP) detectors in high magnetic fields has been investigated. Satisfactory performance in axial fields of up to 3 T has been observed.
Abstract: The behaviour of microchannel plate (MCP) detectors in high magnetic fields has been investigated. Satisfactory performance in axial fields of up to 3 T has been observed.
Patent•
15 Sep 1988
TL;DR: In this article, a microchannel plate with alternating layers of deposited conductive and insulative material was used for channel electron multipliers, with the conductive material having, at holes therethrough in registry, secondary emission coefficients of greater than one and less than one.
Abstract: Channel electron multipliers, including microchannel plates, with alternating layers of deposited conductive and insulative material, the conductive material and insulative material having, at holes therethrough in registry, secondary emission coefficients respectively of greater than one and less than one.
15 Dec 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, an imaging detector based on microchannel plates is constructed for detecting charged and uncharged particles in biomedical samples, which has the advantage over conventional autoradiographic film technique, of short acquisition times and making dynamic studies of living materials possible.
Abstract: An imaging detector system based on microchannel plates is constructed for detecting charged and uncharged particles in biomedical samples. This technique has the advantage over conventional autoradiographic film technique, of short acquisition times and making dynamic studies of living materials possible. The detector consists of a fiber optic window with photocathode, microchannel plates and a resistive anode. The sample is mounted in a slide, which by an automatic sample changer is brought in front of a plastic scintillator fitted on the fiber optic window. The analog signals from the anode are digitized and collected in an image memory. Image processing is performed by an external computer. The expected spatial resolution will be better than 1 mm.
Patent•
02 Sep 1988TL;DR: In this article, a method for depositing a conducting electrode on the output face of a microchannel plate and into the output end of each channel was proposed, where the electrode is vapor deposited by a method which ensures that the material impinges on the image output face from random angles relative to the axis of the channel.
Abstract: A method is provided for depositing a conducting electrode on the output face of a microchannel plate and into the output end of each channel. The electrode is vapor deposited by a method which ensures that the material impinges on the output face from random angles relative to the axis of each channel. A layer (10) of tapering thickness is formed down each channel. When used in an image intensifier tube, for example, the output beam of electrons from each channel is more collimated and the resolution of the tube is improved.
02 Nov 1988
TL;DR: In this article, the authors compared the performance of a large-scale operation with the theory that a MICROCHANNEL HEAT SINKS and MICROLENS DIODE LASER ARRAYS for high-AVERAGE-POWER cw operation.
Abstract: MICROCHANNEL HEAT SINKS AND MICROLENS DIODE LASER ARRAYS MICROCHANNEL HEAT SINKS ARRAYS FOR HIGH-AVERAGE-POWER cw OPERATION OF MASS-TRANSPORTED TWODIMENSIONAL ARRAYS OF GaInAsPIIfiP LASERS 164 ELEMENTS 1x4 mm* MICROCHANNEL HEAT SINKS WASTE POWER DENSITY -OPTICAL POWER DENSITY HEAT EXTRACTION UP TO HUNDREDS OF Wkmz MICROLENS ARRAYS BY MASS TRANSPORT THERMAL PERFORMANCE OBTAINED DIRECTLY FROM LASER THRESHOLD DATA * COMPARISON WITH THEORY
TL;DR: A programmable real-time optical joint transform correlator that generates sharper autocorrelation peaks is presented in this paper, where a microchannel spatial light modulator is utilized as the threshold hard-clipping square-law device.
Abstract: A programmable real-time optical joint transform correlator that generates sharper autocorrelation peaks is presented. A microchannel spatial light modulator is utilized as the threshold hard-clipping square-law device. A liquid crystal television is used to display the input target and reference image. The basic principle of the system and a preliminary experimental result are given.
15 Dec 1988-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the authors investigated the use of a thick microchannel plate as a converter to detect and locate 511 keV photons, and the results indicated a potential for greater than 10% detection efficiency for microchannel plates of 1 cm thickness and 50% lead content.
Abstract: To investigate the use of a thick microchannel plate as a converter to detect and locate 511 keV photons, we have performed model calculations to optimize hole size, spacing and glass material. The results indicate a potential for greater than 10% detection efficiency for microchannel plates of 1 cm thickness and 50% lead content, with 75 μm holes spaced on a lattice of 100 μm. Higher efficiency would be achieved with higher lead content. Such detectors would be operated in a low gain mode with a conventional microchannel plate of gain about 10 5 in proximity. This detector system should be capable of millimeter spatial resolution and nanosecond timing accuracy. These results are sufficiently promising that we suggest a small scale prototype be developed to explore applications in physics and in medical imaging.
TL;DR: In this article, a 40 mm dual microchannel plate intensifier has been developed for use in high-resolution, centroiding, photon-counting systems for astronomy, which incorporates an S.20 photocathode using proximity focus to a dual, double-length micro-channel plate stack in the chevron configuration, resulting electron cloud is proximity-focused onto an aluminized P.20 phosphor screen deposited on a fiber-optic window.
Abstract: Publisher Summary This chapter presents an introduction of microchannel plate (MCP) intensifier for photon counting. The chapter describes the construction and manufacturing techniques required to produce an intensifier of the specification. A 40 mm dual microchannel plate intensifier has been developed for use in high-resolution, centroiding, photon-counting systems for astronomy. The device incorporates an S.20 photocathode using proximity focus to a dual, double-length microchannel plate stack in the chevron configuration. The resulting electron cloud is proximity-focused onto an aluminized P. 20 phosphor screen deposited on a fiber-optic window. The intensifier body is of metal and ceramic construction, metal rings providing the relevant electrode feedthroughs into the vacuum envelope for the microchannel plates, phosphor screen and tube getter. Two, double-length (length-to-diameter ratio of 80: 1), “long life” microchannel plates are used in the “chevron” configuration. An extremely compact, very high-gain, photon-counting image intensifier has been manufactured for use in high-resolution astronomical photoncounting systems.
TL;DR: In this paper, the influence of output electron energy distribution of microchannel plates on the resolution of image intensifiers is discussed. But the authors do not consider the effect of the voltage distribution of the output electrons.
Abstract: Publisher Summary This chapter presents an introduction on the influence of output electron energy distribution of microchannel plates on the resolution of image intensifiers. When a microchannel plate (MCP) is employed in an image intensifier, the energy distribution of its output electrons (EDOE) is a very important factor affecting the resolution. Because of the energy and angle distributions of the output electrons, the spot corresponding to one channel, as detected on a fluorescent screen in close proximity to the channel, spreads out beyond a channel diameter. It has been shown that the resolution of proximity-focusing MCP intensifiers is limited by the EDOE tail extending to energies higher than l00eV. The tail component can be suppressed to a certain degree by depositing an efficient secondary emission material on the micro channel wall near the output end. This is also useful for enhancing the gain.
01 Feb 1988
TL;DR: In this paper, the development and production of a critical night vision electronic device, the microchannel multiplier or microchannel plate (MCP), is discussed, including materials selection, thermo-mechanical processing, chemical processing, mechanical processing, assembly, and cleaning, chemical activation, and electron scrub.
Abstract: : This technical report contains an overview of the development and production of a critical night vision electronic device, the microchannel multiplier or microchannel plate (MCP). Technological challenges and manufacturing processes for the second and third generation image intensifier tube systems are outlined including materials selection, thermo-mechanical processing, chemical processing, mechanical processing, and assembly, and cleaning, chemical activation, and electron scrub. also contained in this report are three figures which chart MCP research and development investment/payoff, unit cost reduction curve for second generation, and estimated production cost comparisons of years 1977 and 1987. The Appendix contains Varian Associates' pamphlet MCP-2819B, Applications for Microchannel Plates.
01 Jan 1988
TL;DR: Two imaging devices using microchannel plate (MCP) intensifiers with 25 and 40 mm active areas that employ the wedge and strip readout system are developed, although some anomalies are visible in the photocathode of the 40 mm device.
Abstract: We have developed two imaging devices(25 and 40 active areas) using microchannel plate (MCP) intensifiers with 25 and 40 mm active areas that employ the wedge and strip readout system. Both devices use a fiber optic input window proximity coupled to a Z stack of microchannel plates. The 25 mm device has an S-20 cathode and uses an A12O3protective layer. On the top MCP, whereas the 40 mm device has a bi-alkali photocathode and no MCP protective layer. Both tubes display peaked pulse amplitude distributions (~60% full width half maximum- FWHM) for single photon events. The 25 mm device has a background of ~250 events sec−1when cooled to −15o C, and achieves a resolution of ~70 µm FWHM at a gain of 1×107. The 40 mm device has a background of ~7 events sec−1at room temperature and attains a resolution of ~70 µm FWHM at a gain of 1.5×107The image linearity and flat field characteristics are generally good, although some anomalies are visible in the photocathode of the 40 mm device.
TL;DR: The performance of two MSLM configurations that can be used to achieve optically bistable operation is discussed and the operating criteria for each mode are investigated, and the results are presented.
Abstract: The performance of two MSLM configurations that can be used to achieve optically bistable operation is discussed. The operating criteria for each mode are investigated, and the results are presented.