Showing papers on "Arcjet rocket published in 2004"

A survey of propulsion options for cargo and piloted missions to Mars.

Abstract: In this paper, high-power electric propulsion options are surveyed in the context of cargo and piloted missions to Mars. A low-thrust trajectory optimization program (RAPTOR) is utilized to analyze this mission. Candidate thrusters are chosen based upon demonstrated performance in the laboratory. Hall, self-field magnetoplasmadynamic (MPDT), self-field lithium Lorentz force accelerator (LiLFA), arcjet, and applied-field LiLFA systems are considered for this mission. In this first phase of the study, all thrusters are assumed to operate at a single power level (regardless of the efficiency-power curve), and the thruster specific mass and powerplant specific mass are taken to be the same for all systems. Under these assumptions, for a 7.5 MW, 60 mT payload, piloted mission, the self-field LiLFA results in the shortest trip time (340 days) with a reasonable propellant mass fraction of 57% (129 mT). For a 150 kW, 9 mT payload, cargo mission, both the applied-field LiLFA and the Hall thruster seem reasonable choices with propellant mass fractions of 42 to 45 % (7 to 8 mT) . The Hall thrusters provide better trip times (530-570 days) compared to the applied-field LiLFA (710 days) for the relatively less demanding mission. Nomenclature

Overview of Major U.S. Industrial Electric Propulsion Programs

Abstract: U.S. industrial activity in electric propulsion remained robust over the past year, with 180 spacecraft worldwide now on orbit using electric propulsion. During the past year, U.S. industry has launched 4 spacecraft using electric propulsion, with over a dozen more in various stages of assembly and test. For the past 12 months, the most notable first was the March launch of Loral’s MBSAT using Russian Hall thrusters for geosynchronous orbit stationkeeping. Additionally, considerable progress has been made developing and qualifying Hall thruster, ion thruster, pulsed plasma thruster, and microthruster system technologies, including power processor and feed system elements. Introduction Electric propulsion continues to gain acceptance in the commercial spacecraft community due to its clear economic advantages over chemical propulsion. During the past year, Loral launched MBSAT, their first spacecraft using Hall thrusters for stationkeeping, Boeing launched one spacecraft using ion thruster systems, Orbital launched a spacecraft using hydrazine resistojets, and Lockheed Martin launched two A2100 spacecraft using arcjet systems. All of these spacecraft are geostationary communications satellites for which electric propulsion provides increased life, increased payload, or decreased launch mass. Figure 1 shows all operational satellites using electric propulsion as of April 2004. In addition to the traditional applications, micropropulsion continues to grow as an area for technology development with efforts focussed on field emission, micro Pulsed Plasma, and colloid thrusters. Micropropulsion technology will allow microsatellites to be organized as local clusters and constellations to provide unique mission capabilities. With the exception of rapid inclination change, kilogram-class microsatellites satellites require 1-to1000 μN thrusters for on-orbit maneuvering. For each of the key technology areas, this paper summarizes the launch status of spacecraft on which it is applied and provides an overview of new technologies under development by U.S. industry. 1 Director, Systems and Technology Development, Associate Fellow AIAA 2 Aerojet log 049-04 Approved for Public Release and Export 40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 11 14 July 2004, Fort Lauderdale, Florida AIAA 2004-3331 Copyright © 2004 by Aerojet General. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.

Spatial Distribution of Lorentz Forces in an Applied-Field Magneto-Plasma-Dynamic Arcjet Plasma

Abstract: In order to clarify the electromagnetic acceleration mechanisms of an applied-field magneto-plasma-dynamic arcjet (MPDA), magnetic fields are measured in detail near the MPDA outlet. Plasma current density is calculated using the Maxwell equation (rotB = µ0 j ), and then spatial distributions of Lorentz forces ( j × B forces) are evaluated. A uniform external magnetic field is deformed by a strong diamagnetic effect near the MPDA outlet, and as a consequence, a converging magnetic nozzle configuration is formed. It is found that an axial Lorentz force Fz (= jrBθ ‐ jθBr) is almost eliminated by the deceleration force (the jθBr force), which results from the diamagnetic effect. The deceleration force can be converted to the acceleration one in an externally-applied diverging magnetic field.

Arcjet Plasma Neutralization of Hall Thrusters, Part 2: Experimental Demonstration

Abstract: The use of an arcjet to provide electron current for a Hall thrusters is examined, as such a hybrid concept can fill a performance niche amongst available space propulsion options. We report on experiments that determine how much electron current can be drawn to a surrogate anode from the plume of low-power arcjets operating on hydrogen and helium and demonstrate the first successful operation of a low-power Hall thruster-arcjet neutralizer package. In the surrogate anode studies, we find that the drawing of current from the arcjet plume has only a weak effect on overall arcjet performance (thrust), with a slight decrease in arc voltage with increased extracted current. A single arcjet Hall thruster hybrid package was assembled for concept demonstration. When operating on helium with a nominal mass flow rate of 4.5 mg/s and at very low power levels (∼70‐120 W), the arcjet was able to effectively neutralize the ∼200‐900-W xenon Hall thruster causing little measurable departure from the hollow-cathode neutralized Hall thruster I-V characteristics up to 250 V. At higher helium mass flow rates, the Hall discharge current was slightly perturbed from its expected values, most likely because of the ingestion of helium in the chamber background.

Production of a High-Mach-Number Plasma Flow for an Advanced Plasma Space Thruster

Abstract: A higher specific impulse and a larger thrust are required for a manned interplanetary space thruster. Prior to a realization of a fusion-plasma thruster, a magneto-plasma-dynamic arcjet (MPDA) powered by a fission reactor is one of the promising candidates for a manned Mars space thruster. The MPDA plasma is accelerated axially by a self-induced j × B force. Thrust performance of the MPDA is expected to increase by applying a magnetic nozzle instead of a solid nozzle. In order to get a much higher thruster performance, two methods have been investigated in the HITOP device, Tohoku University. One is to use a magnetic Laval nozzle in the vicinity of the MPDA muzzle for converting the high ion thermal energy to the axial flow energy. The other is to heat ions by use of an ICRF antenna in the divergent magnetic nozzle. It is found that by use of a small-sized Laval-type magnetic nozzle, the subsonic flow near the muzzle is converted to be supersonic through the magnetic Laval nozzle. A fast-flowing plasma is successfully heated by use of an ICRF antenna in the magnetic beach configuration.

Methane Pyrolysis Stimulated by Admixture of Atomic Hydrogen: 1. An Experimental Study

Abstract: A method for enhancing the hydrocarbon pyrolysis process by introducing atomic hydrogen into the reaction medium from an arcjet plasma source was considered. It was shown that hydrogen atoms could effectively be introduced by mixing under low pressure. The atomic hydrogen–stimulated methane pyrolysis process was experimentally studied in a continuous stirred reactor with a plasma plume. When hydrogen atoms were present in the plasma jet, the amount of the valuable product increased by a factor of two.

Spectroscopic Emission Thermometry of the Microwave Arcjet Chamber Oxygen Plasma

Abstract: The objective of this investigation was to model and experimentally measure the temperature dependent emission spectrum from the microwave arcjet chamber plasma, with oxygen as the propellant. The aluminum cylindrical thruster used for this investigation is sized as a resonant cavity for 2.45 GHz input energy. Converging copper alloy nozzle inserts are used to accelerate the plasma flow. A spectroscopic system consisting of a collimating collection probe mounted on mechanical traverses, fiber optic cable, collimating and focusing lenses, and a Czerney-Turner type spectrometer is used. A Schumann-Runge theoretical spectral model developed assumes an anharmonically vibrating, non-rigid rotating diatomic molecule. For data analysis, the output of the model as a function of temperature from 3,500 to 3,800 Angstroms is tabulated in 25 K increments. The ratios of several strong peaks are compared with experimental data to determine the rotational temperature. Results show a chamber temperature near 2,000 K. The temperature increases slightly with increasing chamber pressure and specific power. The temperature does not appear to vary greatly with spatial location in the plasma. Temperatures near 5,500 K have been measured for microwave arcjet chamber nitrogen plasmas. These higher temperatures may be possible because of greater dissociation energy loss and greater nonequilibrium in oxygen.

Material Spraying Using Electromagnetically Accelerated Plasma Jet

Abstract: In magneto-plasma-dynamic (MPD) arcjet generators, plasma is accelerated by electromagnetic body forces. The MPD arcjet generator can produce higher-velocity, higher-temperature, higher-density and larger-area plasmas than those of conventional thermal plasma torches. Two types of MPD arcjet generator were developed for applications to mullite, zirconia and titanium-nitride spraycoatings. The MPD spray process could successfully form dense, uniform and hard ceramic coatings. In titanium nitride reactive spraying, plasma diagnostic measurement and flowfield analysis were also carried out. A large amount of N and N+ was expected to be exhausted with a high velocity from the MPD generator. Both the electron temperature and the electron number density were kept high at a substrate position compared with those for conventional low-pressure thermal sprayings. A chemically active plasma with excited particles of N+, Ti, Ti+ and Ti2+ was considered to contribute to better titanium nitride coatings. All coating characteristics showed that the MPD arcjet generators had high potentials for ceramic spray coatings.