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Bunch compressor and de-compressor in the FEL for satellite power beaming

Description: A FEL of average power 200 kW is being designed at the LBNL for satellite power beaming. It utilizes the radiation of {approximately} 100 MeV electrons with {approximately} 200 A peak current. In order to obtain the desired peak current, the 5mm long electron bunches delivered by a linear accelerator are compressed to 1mm. Furthermore, it is important for the FEL operations that the compressed bunches have a uniform longitudinal density distribution over the entire bunch length. After the FEL, the electron beam is returned to the linear accelerator for deceleration. Since the electron beam acquires approximately 6% energy spread during radiation in the FEL, bunch de-compressor is used between the FEL and the linac to expand the electron bunches back to their original length and to reduce the energy spread. In this paper we present design and analysis of the bunch compressor and the bunch de-compressor that perform needed functions.
Date: April 28, 1999
Creator: Wan, A. Zholents and W.
Partner: UNT Libraries Government Documents Department

Laser beaming demonstrations to high-orbit satellites

Description: Laser power beaming to satellites and orbital transfer vehicles requires the accurate pointing of a low-divergence laser beam to its target, whether the target is in the sunlight or the earth`s shadow. The Air Force Phillips Laboratory (AFPL) has demonstrated reduction in the image size of stars by a factor of 10 or more by using laser beacons and adaptive optics for atmospheric compensation. This same technology is applicable to reducing the divergence of laser beams propagated from earth to space. A team of Phillips Laboratory, COMSAT Laboratories, and Sandia National Laboratories plans to demonstrate the state of the art in this area with laser-beaming demonstrations to high-orbit satellites. The demonstrations will utilize the 1.5-m diameter telescope with adaptive optics at the AFPL Starfire Optical Range (SOR) and a ruby laser provided by the Air Force and Sandia (1--50 kill and 6 ms at 694.3 nm). The first targets will be corner-cube retro-reflectors left on the moon by the Apollo 11, 14, and 15 landings. We will attempt to use adaptive optics for atmospheric compensation to demonstrate accurate and reliable beam projection with a series of shots over a span of time and shot angle. We will utilize the return signal from the retro-reflectors to help determine the beam diameter on the moon and the variations in pointing accuracy caused by atmospheric tilt. This will be especially challenging because the retro-reflectors will need to be in the lunar shadow to allow detection over background light. If the results from this experiment are encouraging, we will at a later date direct the beam at a COMSAT satellite in geosynchronous orbit as it goes into the shadow of the earth. We will utilize an onboard monitor to measure the current generated in the solar panels on the satellite while the beam is ...
Date: December 31, 1993
Creator: Lipinski, R. J.; Meister, D. C. & Tucker, S.
Partner: UNT Libraries Government Documents Department

Hole-boring through clouds for laser power beaming

Description: Power beaming to satellites with a ground-based laser can be limited by clouds. Hole-boring through the clouds with a laser has been proposed as a way to overcome this obstacle. This paper reviews the past work on laser hole-boring and concludes that hole-boring for direct beaming to satellites is likely to require 10--100 MW. However, it may be possible to use an airborne relay mirror at 10--25 km altitude for some applications in order to extend the range of the laser (e.g., for beaming to satellites near the horizon). In these cases, use of the relay mirror also would allow a narrow beam between the laser and the relay, as well as the possibility of reducing the crosswind if the plane matched speed with the cloud temporarily. Under these conditions, the power requirement to bore a hole through most cirrus and cirrostratus clouds might be only 500-kW if the hole is less than 1 m in diameter and if the crosswind speed is less than 10 m/s. Overcoming cirrus and cirrostratus clouds would reduce the downtime due to weather by a factor of 2. However, 500 kW is a large laser, and it may be more effective instead to establish a second power beaming site in a separate weather zone. An assessment of optimum wavelengths for hole boring also was made, and the best options were found to be 3.0--3.4 {mu}m and above 10 {mu}m.
Date: December 31, 1994
Creator: Lipinski, R.J. & Walter, R.F.
Partner: UNT Libraries Government Documents Department

Space debris removal using a high-power ground-based laser

Description: The feasibility and practicality of using a ground-based laser (GBL) to remove artificial space debris is examined. Physical constraints indicate that a reactor-pumped laser (RPL) may be best suited for this mission, because of its capabilities for multimegawatt output long run-times, and near-diffraction-limited initial beams. Simulations of a laser-powered debris removal system indicate that a 5-MW RPL with a 10-meter-diameter beam director and adaptive optics capabilities can deorbit 1-kg debris from space station altitudes. Larger debris can be deorbited or transferred to safer orbits after multiple laser engagements. A ground-based laser system may be the only realistic way to access and remove some 10,000 separate objects, having velocities in the neighborhood of 7 km/sec, and being spatially distributed over some 10{sup 10} km{sup 3} of space.
Date: December 31, 1993
Creator: Monroe, D. K.
Partner: UNT Libraries Government Documents Department

Multidimensional simulation studies of the SELENE FEL oscillator/buncher followed by a radiator/amplifier output scheme

Description: We analyze and present numerical simulations of the so-called electron output scheme [G. I. Erg et al., 15th Int. FEL Conf., The Hague, The Netherlands, 1993, Book of Abstracts p. 50; Preprint Budker INP 93-75] applied to the SELENE proposal of using a high power FEL to illuminate satellite solar cells. In this scheme, a first stage FEL oscillator bunches the electron beam while a second stage ``radiator`` extracts high power radiation. Our analysis suggests only in the case where the radiator employs a long, tapered undulator will the electron output scheme produce a significant increase in extraction efficiency over what is obtainable from a simple, single-stage oscillator. 1- and 2-D numerical simulations of a 1.7{mu}m FEL employing the electron output scheme show reasonably large bunching fractions ({approximately} 0.3--0.4) at the output of the oscillator stage but only {le}2% extraction efficiency from the radiator stage.
Date: February 1, 1995
Creator: Hahn, S.J. & Fawley, W.M.
Partner: UNT Libraries Government Documents Department

Multi-segment coherent beam combining

Description: Scaling laser systems to large sizes for power beaming and other applications can sometimes be simplified by combing a number of smaller lasers. However, to fully utilize this scaling, coherent beam combination is necessary. This requires measuring and controlling each beam`s pointing and phase relative to adjacent beams using an adaptive optical system. We have built a sub-scale brass-board to evaluate various methods for beam-combining. It includes a segmented adaptive optic and several different specialized wavefront sensors that are fabricated using diffractive optics methods. We have evaluated a number of different phasing algorithms, including hierarchical and matrix methods, and have demonstrated phasing of several elements. The system is currently extended to a large number of segments to evaluate various scaling methodologies.
Date: December 31, 1994
Creator: Neal, D.R.; Tucker, S.D.; Morgan, R.; Smith, T.G.; Warren, M.E.; Gruetzner, J.K. et al.
Partner: UNT Libraries Government Documents Department

Power beaming providing a space power infrastructure

Description: This study, based on two levels of technology, applies the power beaming concept to four planned satellite constellations. The analysis shows that with currently available technology, power beaming can provide mass savings to constellations in orbits ranging from low earth orbit to geosynchronous orbit. Two constellations, space surveillance and tracking system and space based radar, can be supported with current technology. The other two constellations, space-based laser array and boost surveillance and tracking system, will require power and transmission system improvements before their breakeven specific mass is achieved. A doubling of SP-100 conversion efficiency from 10 to 20/% would meet or exceed breakeven for these constellations.
Date: August 1, 1992
Creator: Bamberger, J.A. & Coomes, E.P.
Partner: UNT Libraries Government Documents Department

Near-term feasibility demonstration of laser power beaming

Description: A mission to recharge batteries of satellites in geostationary orbits (geosats) may be a commercially viable application which could be achieved with laser systems somewhat larger than present state-of-the-art. The lifetime of batteries on geosats is limited by repetitive discharge cycles which occur when the satellites are eclipsed by the earth during the spring and fall equinoxes. By coupling high power lasers with modern, large aperture telescopes and laser guide star adaptive optics systems, present day communications satellites could be targeted. It is important that a near term demonstration of laser power beaming be accomplished using lasers in the kilowatt range so that issues associated with high average power be addressed. The Laser Guide Star Facility at LLNL has all the necessary subsystems needed for such a near term demonstration, including high power lasers for both the power beam and guide star, beam directors and satellite tracking system.
Date: January 1, 1994
Creator: Friedman, H. W.
Partner: UNT Libraries Government Documents Department

Fission-activated laser as primary power for CW laser propulsion

Description: Recent advances in the development of reactor-pumped lasers (RPL`s) have stimulated renewed interest in the concept of laser-powered propulsion. This paper surveys a number of laser propulsion concepts and identifies the one that is most promising from the standpoint of practicality. It is proposed that a ground-based FALCON (Fission-Activated Laser CONcept) RPL can provide primary for this launch vehicle design. The laser-vehicle system could launch small payloads into low-earth orbit (LEO) with high repetition rates and at low costs per kilogram. For the favored design, thruster efficiencies are currently estimated to be about 50%, with 80% being seen as a potentially realizable goal after further design refinements. Laser launch system simulations indicate that with a buy-in laser power of 10 MW, it will be possible to obtain specific impulses in the range of 600 to 800 seconds and payload-to-power ratios of 1 to 3 kg/MW.
Date: December 31, 1993
Creator: Monroe, D. K.
Partner: UNT Libraries Government Documents Department

Characterization of a high-intensity subpicosecond XeCl laser system

Description: Recent advances in ultrafast lasers and large-aperture optical amplifiers have spurred the development of terawatt-class laser systems capable of delivering focal-spot intensities in excess of 10{sup 19} W/cm{sup 2}. At these extremely high intensities, the optical field strength is more than twenty times larger than the Bohr electric field, e/a{sub o}{sup 2}, permitting for the first time investigations of the optical properties of matter in a previously unexplored intensity regime. We describe a terawatt-class laser system based on the amplification of subpicosecond pulses in XeCl discharge amplifiers. Although several terawatt laser systems have been previously reported, complete characterization of the performance of these devices has not been made: Only for a few of these systems has the final output pulsewidth been determined, while measurements of the focal-spot diameter obtained upon focusing of the fully amplified beam have not been reported at all. 9 refs., 4 figs.
Date: January 1, 1990
Creator: Taylor, A.J.; Gosnell, T.R.; Roberts, J.P.; MacPherson, D.C. & Tallman, C.R.
Partner: UNT Libraries Government Documents Department

Laser power beaming to extend lives of GSO NiCd satellites

Description: It is proposed that a ground-based laser can beam power to commercial communication satellites in geosynchronous orbit and reduce battery depth-of-discharge during eclipses. Two laser system designs are presented which have the capability of reducing battery discharge by 100%. Both utilize a steerable beam director, with a mirror diameter of 4 meters in one case and 8 meters in the other. Both also use an adaptive optics unit within the beam train to provide real-time corrections for wavefront distortions caused by atmospheric turbulence. The required system power output is in the range of 100 to 200 kW for a transmitted wavelength just under 900 nm. Laser power beaming can nearly double the remaining lifetime of a satellite that uses NiCd batteries. However, by the time such lasers become available, nearly all NiCd satellites will be replaced by NiH{sub 2} satellites, which stand to benefit much less from power beaming.
Date: December 31, 1993
Creator: Monroe, D. K.
Partner: UNT Libraries Government Documents Department

Phased-array antenna control by a monolithic photonic integrated circuit, COMPASS

Description: Phased-array antenna systems are well known for rapid beam steering and their ability to bring high power to the target. Such systems are also quite complex and heavy, which have limited their usefulness. The issues of weight, size, power use, and complexity have been addressed through a system named COMPASS (Coherent Optical Monolithic Phased Array Steering System). All phased-array antenna systems need: (1) small size; (2) low power use; (3) high-speed beam steering; and (4) digitally-controlled phase shifting. COMPASS meets these basic requirements, and provides some very desirable additional features. These are: (1) phase control separate from the transmit/receive module; (2) simple expansion to large arrays; (3) fiber optic interconnect for reduced sensitivity to EMI; (4) an intrinsically radiation-hard GaAs chip; and (5) optical power provided by a commercially available continuous wave (CW) laser. 4 refs., 8 figs.
Date: January 1, 1991
Creator: Kravitz, S.H.; Hietala, V.M.; Vawter, G.A. & Meyer, W.J.
Partner: UNT Libraries Government Documents Department

Subpicosecond, high-brightness excimer laser systems

Description: Subpicosecond, high-brightness excimer laser systems are being used to explore the interaction of intense coherent ultraviolet radiation with matter. Applications of current systems include generation of picosecond x-ray pulses, investigation of possible x-ray laser pumping schemes, studies of multiphoton phenomena in atomic species, and time-resolved photochemistry. These systems, based on the amplification of subpicosecond pulses in small aperture (/approximately/1 cm/sup 2/) XeCl or KrF amplifiers, deliver focal spot intensities of /approximately/10/sup 17/ W/cm/sup 2/. Scaling to higher intensities, however, will require an additional large aperture amplifier which preserves near-diffraction-limited beam quality and subpicosecond pulse duration. We describe here both a small aperture KrF system which routinely provides intensities >10/sup 17/ W/cm/sup 2/ to several experiments, and a large aperture XeCl system designed to deliver /approximately/1 J subpicosecond pulses and yield intensities on target in excess of 10/sup 19/W/cm/sup 2/. We also discuss the effects of two-photon absorption on large-aperture, high-brightness excimer lasers. 4 refs., 2 figs.
Date: January 1, 1988
Creator: Taylor, A.J.; Gosnell, T.R.; Roberts, J.P.; Lester, C.S.; Gibson, R.B.; Harper, S.E. et al.
Partner: UNT Libraries Government Documents Department

Pulsed laser propulsion for low cost, high volume launch to orbit

Description: Pulsed laser propulsion offers the prospect of delivering high thrust at high specific impulse (500-1000 seconds) from a very simple thruster, using the energy of a remote ground-based laser to heat an inert propellant. Current analyses indicate that payloads of approximately 1 kg per megawatt of average laser power can be launched at a rate of one payload every 15 minutes and a marginal cost of $20 to $200 per kg. A 20 MW entry-level launch system could be built using current technology at a cost of $500 million or less; it would be capable of placing 600 tons per year into LEO. The SDIO Laser Propulsion Program has been developing the technology for such a launch system since 1987. The program has conducted theoretical and experimental research on a particular class of laser-driven thruster, the planar double-pulse LSD-wave thruster, which could be used for a near-term launcher. The double-pulse thruster offers several advantages, including extreme simplicity, design flexibility, and the ability to guide a vehicle remotely by precise control of the laser beam. Small-scale experiments have demonstrated the operation of this thruster at a specific impulse of 600 seconds and 10% efficiency; larger experiments now under way are expected to increase this to at least 20% efficiency. Systems-level issues, from guidance and tracking to possible unique applications, have also been considered and will be briefly discussed. There appear to be no fundamental obstacles to creating, in the next five to ten years, a new low-cost ''pipe-line to space.'' 7 refs., 2 figs., 1 tab.
Date: June 2, 1989
Creator: Kare, J.
Partner: UNT Libraries Government Documents Department

Beam-powered lunar rover design

Description: Manned exploration of our nearest neighbors in the solar systems is the primary goal of the Space Exploration Initiative (SEI). An integral part of any manned lunar or planetary outpost will be a system for manned excursions over the surface of the planet. This report presents a preliminary design for a lunar rover capable of supporting four astronauts on long-duration excursions across the lunar landscape. The distinguishing feature of this rover design is that power is provided to rover via a laser beam from an independent orbiting power satellite. This system design provides very high power availability with minimal mass on the rover vehicle. With this abundance of power, and with a relatively small power-system mass contained in the rover, the vehicle can perform an impressive suite of mission-related activity. The rover might be used as the first outpost for the lunar surface (i.e., a mobile base). A mobile base has the advantage of providing extensive mission activities without the expense of establishing a fixed base. This concept has been referred to as Rove First.'' A manned over, powered through a laser beam, has been designed for travel on the lunar surface for round-trip distances in the range of 1000 km, although the actual distance traveled is not crucial since the propulsion system does not rely on energy storage. The life support system can support a 4-person crew for up to 30 days, and ample power is available for mission-related activities. The 8000-kg rover has 30 kW of continuous power available via a laser transmitter located at the Earth-moon L1 libration point, about 50,000 km above the surface of the moon. This rover, which is designed to operate in either day or night conditions, has the flexibility to perform a variety of power-intensive missions. 24 refs.
Date: March 1, 1992
Creator: Dagle, J.E.; Coomes, E.P.; Antoniak, Z.I.; Bamberger, J.A.; Bates, J.M.; Chiu, M.A. et al.
Partner: UNT Libraries Government Documents Department

Experimental characteristics of a high-gain free-electron laser amplifier operating at 8-mm and 2-mm wavelengths

Description: The Electron Laser Facility (ELF) at the Lawrence Livermore National Laboratory (LLNL) uses a high-current induction linac (3.5 MeV, 1000 A), in conjunction with a pulsed electromagnetic wiggler (4.0 M, 4000 G), to operate a free electron laser (FEL) that produces intense radiation in the microwave regime (2 to 8 mm). ELF is a high-gain, single-pass amplifier, using a commercial microwave source as an oscillator input (200 W-50 kW). Previous experiments at 35 GHz produced exponential gains of 40 dB/m, peak powers exceeding 1 GW, and beam-to-rf conversion efficiencies of 34%. Recent experiments at 140 GHz have demonstrated exponential gains of 22 dB/m, peak powers exceeding 50 MW, and total gains of 65 dB. In this paper, we describe the experimental results at these two frequencies and compare then with the predictions of simulation codes.
Date: June 8, 1987
Creator: Throop, A.L.; Orzechowski, T.J.; Anderson, B.R.; Chambers, F.W.; Clark, J.C.; Fawley, W.M. et al.
Partner: UNT Libraries Government Documents Department

A fast radiation-to-coherent light converter

Description: We have developed a radiation-to-coherent light converter (RCLC) with a monolithically integrated semiconductor chip that consists of a chromium-doped GaAs photoconductor detector modulates the laser diode, which has been biased above the lasing threshold, thus converting a radiation pulse to an electric pulse and then to a light pulse. The laser pulse is then transmitted to a fast recorder through a high-bandwidth optical fiber. In the absence of a single-step x-ray pumped laser, our converter appears to be the first integrated device that can efficiently convert x-ray flux into coherent light. This device has been tested successfully with the 50-ps electron beams of a 17-MeV linear accelerator and with 50-ns x-ray pulses from a Z-pinch plasma source. 2 refs., 9 figs.
Date: September 9, 1988
Creator: Wang, C.L.; Flatley, J.E.; Stewart, P.H.; Bar-Chaim, N.; Lau, K.Y.; Ury, I. et al.
Partner: UNT Libraries Government Documents Department

A megajoule class krypton fluoride amplifier for single shot, high gain ICF application

Description: A design study is underway to define the optimal architecture for a KrF laser system which will deliver 10 MJ of 248-nm light to an ICF target. We present one approach which incorporates final power amplifiers in the megajoule class, achieving 10 MJ with four final amplifiers. Each double-pass laser amplifier employs two-sided electron-beam pumping of the laser gas medium. Details of the design are based on a Monte-Carlo electron-beam deposition code, a one-dimensional, time-dependent kinetics code, and pulsed power circuit modeling. Linear dimensions of the amplifier's extracted gain volume are 6.25 m in height and length and 5.12 m in width. Each amplifier handles 160 angularly multiplexed laser channels. The one-amagat, krypton-rich laser medium is e-beam pumped at 60-kW cm/sup /minus/3/ (4-MA at3.3-MV) over the 2-microsecond duration of the laser beam pulse train. 5 refs., 4 figs.
Date: January 1, 1988
Creator: Rose, E.; Hanson, D.; Krohn, B.; McLeod, J. & Kang, M.
Partner: UNT Libraries Government Documents Department

Application of reactor-pumped lasers to power beaming

Description: Power beaming is the concept of centralized power generation and distribution to remote users via energy beams such as microwaves or laser beams. The power beaming community is presently performing technical evaluations of available lasers as part of the design process for developing terrestrial and space-based power beaming systems. This report describes the suitability of employing a nuclear reactor-pumped laser in a power beaming system. Although there are several technical issues to be resolved, the power beaming community currently believes that the AlGaAs solid-state laser is the primary candidate for power beaming because that laser meets the many design criteria for such a system and integrates well with the GaAs photodiode receiver array. After reviewing the history and physics of reactor-pumped lasers, the advantages of these lasers for power beaming are discussed, along with several technical issues which are currently facing reactor-pumped laser research. The overriding conclusion is that reactor-pumped laser technology is not presently developed to the point of being technially or economically competitive with more mature solid-state technologies for application to power beaming. 58 refs.
Date: October 1, 1991
Creator: Repetti, T.E.
Partner: UNT Libraries Government Documents Department

Satellite power system concept development and evaluation program system definition technical assessment report

Description: The results of the system definition studies conducted by NASA as a part of the Department of Energy/National Aeronautics and Space Administration SPS Concept Development and Evaluation Program are summarized. The purpose of the system definition efforts was to identify and define candidate SPS concepts and to evaluate the concepts in terms of technical and cost factors. Although the system definition efforts consisted primarily of evaluation and assessment of alternative technical approaches, a reference system was also defined to facilitate economic, environmental, and societal assessments by the Department of Energy. This reference system was designed to deliver 5 GW of electrical power to the utility grid. Topics covered include system definition; energy conversion and power management; power transmission and reception; structures, controls, and materials; construction and operations; and space transportation.
Date: December 1, 1980
Partner: UNT Libraries Government Documents Department

Program assessment report, statement of findings. Satellite power systems concept development and evaluation program

Description: What is known, uncertain, and unknown about the Solar Power Satellite (SPS) concept is stated. The important technical, environmental, and cost goal questions that must be answered prior to making a commitment to the SPS concept are discussed. Although significant technological, environmental and economic questions remain to be answered, the preliminary investigations undertaken in the CDEP do provide a basis for a policy decision on further commitment. Also, areas of research and experimentation required to acquire the knowledge by which a series of informed, time-phased decisions may be made concerning the possibility of the SPS concept playing a major role in the United States' energy future are suggested.
Date: November 1, 1980
Partner: UNT Libraries Government Documents Department

A new method for power generation and distribution in outer space

Description: The power system is a major component of a space system's size, mass, technical complexity, and hence, cost. To date, space systems include the energy source as an integral part of the mission satellite. Potentially significant benefit could be realized by separating the energy source from the end-use system and transmitting the power via an energy beam (power beaming) (Coomes et al., 1989). This concept parallels the terrestrial central generating station and transmission grid. In this summary, the system components required for power beaming implementation are outlined and applied to a satellite for power beaming implementation are outlined and applied to a satellite constellation to demonstrate the feasibility of implementing power beaming in the next 20 years. 5 refs., 1 fig., 3 tabs.
Date: September 1, 1989
Creator: Bamberger, J.A.
Partner: UNT Libraries Government Documents Department