Studies Of A Repetitively Pulsed Laser Powered Thruster
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| Author | : David I. Rosen |
| Publisher | : |
| Total Pages | : 94 |
| Release | : 1982 |
| Genre | : |
| ISBN | : |
In this report we present results of continuing analytical and experimental investigations carried out to evaluate the concept of pulsed laser propulsion. This advanced propulsion scheme, which has been the subject of several previous studies, involves supplying propellant energy by beaming short, repetitive laser pulses to a thruster from a remote laser power station. The concept offers the advantages of a remote power source, high specific impulse, high payload to total mass ratio (a consequence of the first two features) and moderate to high thrust (limited primarily by the average laser power available). The present research addresses questions related to thruster performance and optical design. In the thruster scheme under consideration, parabolic nozzle walls focus the incoming laser beam to yield breakdown in a propellant at the focal point of the parabola. The resulting high pressure plasma is characteristic of a detonation wave initiation by high power laser-induced breakdown. With a short laser pulse, the detonation wave quickly becomes a blast wave which propagates to the nozzle exit plane converting the high pressure of the gas behind it to a force on the nozzle wall. Propellant is fed to the focal region from a plenum chamber. The laser-induced blast wave stops the propellant flow through the throat until the pressure at the throat decays to the sonic pressure; then the propellant flow restarts. The process is repeated with each successive laser pulse.
| Author | : Takashi Abe |
| Publisher | : |
| Total Pages | : 22 |
| Release | : 1989 |
| Genre | : Lasers in aeronautics |
| ISBN | : |
An experimental study of quasi-steady operation of repetitively-pulsed laser thruster was conducted by using Kr-F laser of 100 pps (pulse per second). The measured impulse coupling coefficient is comparable to the result previously reported and the theoretical value predicted by the transparent vapor model. The thrust level in a quasi-steady operation can be estimated as the impulse coupling coefficient multiplied by the average power of the laser beam, since the time in which the recoil momentum is delivered by each shot of laser beam is satisfactorily smaller than the laser pulse interval. The specific impulse is also measured. It is larger than the theoretical value predicted from the transparent vapor model. During a few thousand shots of laser, there was not much reduction in the impulse coupling coefficient at the present laser power of a few watts. The new configuration in which the thrust vector is anti-parallel to the laser beam is proposed and is demonstrated.
| Author | : David I. Rosen |
| Publisher | : |
| Total Pages | : 270 |
| Release | : 1982 |
| Genre | : |
| ISBN | : |
This report describes experimental and analytical studies on pulsed laser propulsion. Volume I describes thruster performance and phenomenology studies. They include. They include theoretical investigations of laser-induced gas breakdown at 10.6 microns and 0.35 microns, the development of a detailed computer model of the quasi-one dimensional nonsteady flow of real gases in the nozzle, and small-scale thruster performance and absorption physics experiments using pulsed CO2 (10.6 microns) and XeF (0.35 microns) lasers. Volume II contains the results of mission analysis studies to evaluate the system requirements of some candidate defense-related missions for pulsed laser propulsion. These studies address the problem of orbit-to-orbit transfer of satellites, as well as the launch of a vehicle from the earth.
| Author | : Kouchi Mori |
| Publisher | : |
| Total Pages | : |
| Release | : 2001 |
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| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : |
| Release | : 1989 |
| Genre | : |
| ISBN | : |
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.
| Author | : |
| Publisher | : |
| Total Pages | : 10 |
| Release | : 1989 |
| Genre | : Lasers in aeronautics |
| ISBN | : |
| Author | : Jacques C. Richard |
| Publisher | : |
| Total Pages | : 125 |
| Release | : 1989 |
| Genre | : |
| ISBN | : |
| Author | : Albert F. Kascak |
| Publisher | : |
| Total Pages | : 28 |
| Release | : 1974 |
| Genre | : Lasers in astronautics |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : 8 |
| Release | : 2007 |
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| ISBN | : |
Our objective is to develop an engine with high efficiency, and specific impulse which can be varied over more than an order of magnitude to match the requirements of efficient spacecraft propulsion in the constant momentum propulsion regime. Laser ablation propulsion uniquely offers an almost arbitrarily large range of exhaust velocity, since it depends only on incident laser intensity. We have shown that thrust efficiency remains good over the specific impulse range 150 to 3,200 seconds. Considering a laser ablation propulsion device as an electric thruster, use of energetic ablation fuels can give thrust electrical efficiency greater than unity at the bottom of this Isp range. In our laser plasma thrusters (LPT's), we have demonstrated specific impulse which can be varied over a factor-of-15, from 200 to 3000 seconds to match the velocity profile in a mission. The corresponding thrust efficiency varies from 165% to 40%. The micro-LPT product has a 0.1 - 10 mN thrust range. After reviewing the science basis and performance of the existing devices, we describe the unique capabilities predicted for the LPT technology when it is scaled to the 1N thrust level. This scaling permits taking full advantage of the technology's inherent advantages in thrust/power ratio (up to 1.35N/kW), thrust efficiency and thrust density (5,000 to 350,000N/m2). However, the most important capability of the "macro-LPT" design is variable Isp for optimally-efficient, constant-momentum flights. Claims made for the macro-LPT are based on measured performance of our millisecond and nanosecond-pulse LPT devices, and the anticipated performance of a revolutionary liquid ablation fuel.
| Author | : National Aeronautics and Space Administration (NASA) |
| Publisher | : Createspace Independent Publishing Platform |
| Total Pages | : 146 |
| Release | : 2018-07-17 |
| Genre | : |
| ISBN | : 9781722973629 |
An extensive numerical experiment, using the developed computer code, was conducted to design an optimized laser-sustained hydrogen plasma thruster. The plasma was sustained using a 30 kW CO2 laser beam operated at 10.6 micrometers focused inside the thruster. The adopted physical model considers two-dimensional compressible Navier-Stokes equations coupled with the laser power absorption process, geometric ray tracing for the laser beam, and the thermodynamically equilibrium (LTE) assumption for the plasma thermophysical and optical properties. A pressure based Navier-Stokes solver using body-fitted coordinate was used to calculate the laser-supported rocket flow which consists of both recirculating and transonic flow regions. The computer code was used to study the behavior of laser-sustained plasmas within a pipe over a wide range of forced convection and optical arrangements before it was applied to the thruster design, and these theoretical calculations agree well with existing experimental results. Several different throat size thrusters operated at 150 and 300 kPa chamber pressure were evaluated in the numerical experiment. It is found that the thruster performance (vacuum specific impulse) is highly dependent on the operating conditions, and that an adequately designed laser-supported thruster can have a specific impulse around 1500 sec. The heat loading on the wall of the calculated thrusters were also estimated, and it is comparable to heat loading on the conventional chemical rocket. It was also found that the specific impulse of the calculated thrusters can be reduced by 200 secs due to the finite chemical reaction rate. Jeng, San-Mou and Litchford, Ronald and Keefer, Dennis Unspecified Center COMPUTER AIDED DESIGN; HYDROGEN PLASMA; LASER APPLICATIONS; LASER PROPULSION; NAVIER-STOKES EQUATION; PLASMA PROPULSION; FINITE DIFFERENCE THEORY; FORCED CONVECTION; PRESSURE EFFECTS; RAY TRACING; REACTION KINETICS; THERMODYNAMIC EQUILIBRIUM; TRANSONIC FLOW...
