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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

A structural and thermal packaging approach for power processing units for 30-cm ion thrusters

Solar Electric Propulsion (SEP) is currently being studied for possible use in a number of near earth and planetary missions. The thruster subsystem for these missions would consist of 30 centimeter ion thrusters with Power Processor Units (PPU) clustered in assemblies of from two to ten units. A preliminary design study of the electronic packaging of the PPU has been completed at Lewis Research Center of NASA. This study evaluates designs meeting the competing requirements of low system weight and overall mission flexibility. These requirements are evaluated regarding structural and thermal design, electrical efficiency, and integration of the electrical circuits into a functional PPU layout.

Maloy, J. E.↗
NASA NTRS1983

Simplified power processing for ion-thruster subsystems

Compared to chemical propulsion, ion propulsion offers distinct payload-mass increases for many future low-thrust earth-orbital and deep-space missions. Despite this advantage, the high initial cost and complexity of ion-propulsion subsystems reduce their attractiveness for most present and near-term spacecraft missions. Investigations have, therefore, been conducted with the objective to attempt to simplify the power-processing unit (PPU), which is the single most complex and expensive component in the thruster subsystem. The present investigation is concerned with a program to simplify the design of the PPU employed in a 8-cm mercury-ion-thruster subsystem. In this program a dramatic simplification in the design of the PPU could be achieved, while retaining essential thruster control and subsystem operational flexibility.

Wessel, F. J.↗
NASA NTRS1996

Oligomerization of uridine phosphorimidazolides on montmorillonite: a model for the prebiotic synthesis of RNA on minerals

The 5'-phosphorimidazolide of uridine reacts on Na(+)-montmorillonite 22A in aqueous solution to give oligomers as long as 7 mers. The maximum chain length increases to 9 mers and the overall oligomer yield increases when 9:1 ImpU, A5' ppA mixtures react under the same conditions. The oligomer yield and maximum chain length decreases with the structure of the added pyrophosphate in the order A5' ppA > A5' ppU > U5' ppU. Structure analysis of individual oligomer fractions was performed by selective enzymatic hydrolyses followed by HPLC analysis of the products. The regioselectivity for 3',5'-bond formation is 80-90% in the 9:1 ImpU, A5' ppA reaction, a percentage comparable to that observed in the 9:1 ImpA, A5' ppA reaction. Oligomerization of ImpU is inhibited by addition of dA5' ppdA, and MeppA. No oligomers containing A5' ppU were products of the 9:1 ImpU,A5' ppA reaction, a finding consistent with the simple addition of the ImpU to the A5' ppA and not the rearrangement of an ImpU-A5' ppA adduct. Concentrations of lysine or arginine which were close to that of the ImpU did not inhibit oligomer formation. Treatment of Na(+)-montmorillonite with 1 M arginine yielded arginine-montmorillonite, an amino acid-mineral adduct which did not catalyze ImpU oligomerization. Neither the 4-9 mers formed in the 9:1 ImpU, A5' ppA reaction nor the 4-9 mers formed by the base hydrolysis of poly(U) served as templates for the formation of oligo(A)s.

Non-NASA Center↗
NASA NTRS1996

NSTAR Ion Propulsion System Power Electronics

The NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) program, managed by the Jet Propulsion Laboratory (JPL), is currently developing a high performance, simplified ion propulsion system. This propulsion system, which is throttleable from 0.5- to 2.3-kW output power to the thruster, targets primary propulsion applications for planetary and Earth-space missions and has been baselined as the primary propulsion system for the first New Millennium spacecraft. The NASA Lewis Research Center is responsible for the design and delivery of a breadboard power processing unit (PPU) and an engineering model thruster (EMT) for this system and will manage the contract for the delivery of the flight hardware to JPL. The PPU requirements, which dictate a mass of less than 12 kg with an efficiency of 0.9 or greater at a 2.3-kW output, forced a departure from the state-of-the-art ion thruster PPU design. Several innovations--including dual-use topologies, simplified thruster control, and the use of ferrite magnetic materials--were necessary to meet these requirements.

Source record↗
NASA NTRS2013

Extreme Environment Capable, Modular and Scalable Power Processing Unit for Solar Electric Propulsion

This paper is to present a concept of a modular and scalable High Temperature Boost (HTB) Power Processing Unit (PPU) capable of operating at temperatures beyond the standard military temperature range. The various extreme environments technologies are also described as the fundamental technology path to this concept. The proposed HTB PPU is intended for power processing in the area of space solar electric propulsion, where reduction of in-space mass and volume are desired, and sometimes even critical, to achieve the goals of future space flight missions. The concept of the HTB PPU can also be applied to other extreme environment applications, such as geothermal and petroleum deep-well drilling, where higher temperature operation is required.

Carr, Gregory A.↗
NASA NTRS2013

High Voltage Hall Accelerator Propulsion System Development for NASA Science Missions

NASA Science Mission Directorates In-Space Propulsion Technology Program is sponsoring the development of a 3.8 kW-class engineering development unit Hall thruster for implementation in NASA science and exploration missions. NASA Glenn Research Center and Aerojet are developing a high fidelity high voltage Hall accelerator (HiVHAc) thruster that can achieve specific impulse magnitudes greater than 2,700 seconds and xenon throughput capability in excess of 300 kilograms. Performance, plume mappings, thermal characterization, and vibration tests of the HiVHAc engineering development unit thruster have been performed. In addition, the HiVHAc project is also pursuing the development of a power processing unit (PPU) and xenon feed system (XFS) for integration with the HiVHAc engineering development unit thruster. Colorado Power Electronics and NASA Glenn Research Center have tested a brassboard PPU for more than 1,500 hours in a vacuum environment, and a new brassboard and engineering model PPU units are under development. VACCO Industries developed a xenon flow control module which has undergone qualification testing and will be integrated with the HiVHAc thruster extended duration tests. Finally, recent mission studies have shown that the HiVHAc propulsion system has sufficient performance for four Discovery- and two New Frontiers-class NASA design reference missions.

Kamhawi, Hani↗
NASA NTRS2013

Extreme Environment Capable, Modular and Scalable Power Processing Unit for Solar Electric Propulsion

This paper is to present a concept of a modular and scalable High Temperature Boost (HTB) Power Processing Unit (PPU) capable of operating at temperatures beyond the standard military temperature range. The various extreme environments technologies are also described as the fundamental technology path to this concept. The proposed HTB PPU is intended for power processing in the area of space solar electric propulsion, where the reduction of in-space mass and volume are desired, and sometimes even critical, to achieve the goals of future space flight missions. The concept of the HTB PPU can also be applied to other extreme environment applications, such as geothermal and petroleum deep-well drilling, where higher temperature operation is required.

Electronics↗
NASA NTRS2015

Rocket Propulsion 21 Steering Committee Meeting (RP21) NASA In-Space Propulsion Update

In-house Support of NEXT-C Contract Status Thruster NEXT Long Duration Test post-test destructive evaluation in progress Findings will be used to verify service life models identify potential design improvements Cathode heater fabrication initiated for cyclic life testing Thruster operating algorithm definition verification initiated to provide operating procedures for mission users High voltage propellant isolator life test voluntarily terminated after successfully operating 51,200 h Power processor unit (PPU) Replaced all problematic stacked multilayer ceramic dual inline pin capacitors within PPU Test bed Rebuilt installed discharge power supply primary power board Completed full functional performance characterization Final test report in progress Transferred PPU Testbed to contractor to support prototype design effort.

Electric Propulsion↗
NASA NTRS2015

Iodine Satellite

The Iodine Satellite (iSat) spacecraft will be the first CubeSat to demonstrate high change in velocity from a primary propulsion system by using Hall thruster technology and iodine as a propellant. The mission will demonstrate CubeSat maneuverability, including plane change, altitude change and change in its closest approach to Earth to ensure atmospheric reentry in less than 90 days. The mission is planned for launch in fall 2017. Hall thruster technology is a type of electric propulsion. Electric propulsion uses electricity, typically from solar panels, to accelerate the propellant. Electric propulsion can accelerate propellant to 10 times higher velocities than traditional chemical propulsion systems, which significantly increases fuel efficiency. To enable the success of the propulsion subsystem, iSat will also demonstrate power management and thermal control capabilities well beyond the current state-of-the-art for spacecraft of its size. This technology is a viable primary propulsion system that can be used on small satellites ranging from about 22 pounds (10 kilograms) to more than 1,000 pounds (450 kilograms). iSat's fuel efficiency is ten times greater and its propulsion per volume is 100 times greater than current cold-gas systems and three times better than the same system operating on xenon. iSat's iodine propulsion system consists of a 200 watt (W) Hall thruster, a cathode, a tank to store solid iodine, a power processing unit (PPU) and the feed system to supply the iodine. This propulsion system is based on a 200 W Hall thruster developed by Busek Co. Inc., which was previously flown using xenon as the propellant. Several improvements have been made to the original system to include a compact PPU, targeting greater than 80 percent reduction in mass and volume of conventional PPU designs. The cathode technology is planned to enable heaterless cathode conditioning, significantly increasing total system efficiency. The feed system has been designed to include iodine compatible control valves with internal heaters and temperature sensors to coincide with the iodine-compatible thruster. A key advantage to using iodine as a propellant is that it may be stored in the tank as an unpressurized solid on the ground and before flight operations. During operations, the tank is heated to vaporize the propellant. Iodine vapor is then routed through custom flow control valves to control mass flow to the thruster and cathode assembly. The thruster then ionizes the vapor and accelerates it via magnetic and electrostatic fields, resulting in high specific impulse, characteristic of a highly efficient propulsion system. The iSat spacecraft is a 12-unit (12U) CubeSat with dimensions of about 8 inches x 8 inches x 12 inches (20 centimeters x 20 centimeters x 30 centimeters). The spacecraft frame will be constructed from aluminum with a finish to prevent iodine-driven corrosion. The iSat spacecraft includes full three-axis control and will leverage heat generated by spacecraft components and radiators for a passive thermal control system. After the CubeSat has successfully detached from its launch vehicle, it will deploy its solar panels, correct for tip-off and maintain attitude control before ground contact. An initial check-out period of two weeks is planned for testing all subsystems. The spacecraft will charge the power system while in sunlight, using momentum wheels and magnetic torque rods to rotate the vehicle to the required attitude.

iSat↗
NASA NTRS2016

Integration Tests of the 4 kW-Class High Voltage Hall Accelerator Power Processing Unit with the HiVHAc and the SPT-140 Hall Effect Thrusters

NASA's Science Mission Directorate is sponsoring the development of a 4 kW-class Hall propulsion system for implementation in NASA science and exploration missions. The main components of the system include the High Voltage Hall Accelerator (HiVHAc), an engineering model power processing unit (PPU) developed by Colorado Power Electronics, and a xenon flow control module (XFCM) developed by VACCO Industries. NASA Glenn Research Center is performing integrated tests of the Hall thruster propulsion system. This paper presents results from integrated tests of the PPU and XFCM with the HiVHAc engineering development thruster and a SPT-140 thruster provided by Space System Loral. The results presented in this paper demonstrate thruster discharge initiation along with open-loop and closed-loop control of the discharge current with anode flow for both the HiVHAc and the SPT-140 thrusters. Integrated tests with the SPT-140 thruster indicated that the PPU was able to repeatedly initiate the thruster's discharge, achieve steady state operation, and successfully throttle the thruster between 1.5 and 4.5 kW. The measured SPT-140 performance was identical to levels reported by Space Systems Loral.

Power Processing Unit↗
NASA NTRS2016

Integration Tests of the 4 kW-class High Voltage Hall Accelerator Power Processing Unit with the HiVHAc and the SPT-140 Hall Effect Thrusters

NASAs Science Mission Directorate is sponsoring the development of a 4 kW-class Hall propulsion system for implementation in NASA science and exploration missions. The main components of the system include the High Voltage Hall Accelerator (HiVHAc), an engineering model power processing unit (PPU) developed by Colorado Power Electronics, and a xenon flow control module (XFCM) developed by VACCO Industries. NASA Glenn Research Center is performing integrated tests of the Hall thruster propulsion system. This presentation presents results from integrated tests of the PPU and XFCM with the HiVHAc engineering development thruster and a SPT-140 thruster provided by Space System Loral. The results presented in this paper demonstrate thruster discharge initiation, open-loop and closed-loop control of the discharge current with anode flow for both the HiVHAc and the SPT-140 thrusters. Integrated tests with the SPT-140 thruster indicated that the PPU was able to repeatedly initiate the thrusters discharge, achieve steady state operation, and successfully throttle the thruster between 1.5 and 4.5 kW. The measured SPT-140 performance was identical to levels reported by Space Systems Loral.

Hall Thrusters↗
NASA NTRS2015

Low-Power Operation and Plasma Characterization of a Qualification Model SPT-140 Hall Thruster for NASA Science Missions

Hall thruster systems based on commercial product lines can potentially lead to lower cost electric propulsion (EP) systems for deep space science missions. A 4.5-kW SPT-140 Hall thruster presently under qualification testing by SSL leverages the substantial heritage of the SPT-100 being flown on Russian and US commercial satellites. The Jet Propulsion Laboratory is exploring the use of commercial EP systems, including the SPT-140, for deep space science missions, and initiated a program to evaluate the SPT-140 in the areas of low power operation and thruster operating life. A qualification model SPT-140 designated QM002 was evaluated for operation and plasma properties along channel centerline, from 4.5 kW to 0.8 kW. Additional testing was performed on a development model SPT-140 designated DM4 to evaluate operation with a Moog proportional flow control valve (PFCV). The PFCV was commanded by an SSL engineering model PPU-140 Power Processing Unit (PPU). Performance measurements on QM002 at 0.8 kW discharge power were 50 mN of thrust at a total specific impulse of 1250 s, a total thruster efficiency of 0.38, and discharge current oscillations of under 3% of the mean current. Steady-state operation at 0.8 kW was demonstrated during a 27 h firing. The SPT-140 DM4 was operated in closed-loop control of the discharge current with the PFCV and PPU over discharge power levels of 0.8-4.5 kW. QM002 and DM4 test data indicate that the SPT-140 design is a viable candidate for NASA missions requiring power throttling down to low thruster input power.

Garner, Charles E.↗
NASA NTRSDate not supplied

A Summary of the NEXT-C Flight Thruster Proto-flight Testing

Aerojet Rocketdyne (AR), under contract to NASA Glenn Research Center, built, tested and delivered the first flight version of the NEXT-C (NASA Evolutionary Xenon Thruster – Commercial) engine system. This system is comprised of a 7 kW thruster and power processing unit which are the commercial variants of the NEXT prototype thruster and power processing unit. In addition to developing the NEXT-C engine system for potential future NASA science missions, AR is dedicated to ensuring that this propulsion system is viable for commercial users and a wider variety of commercial applications. This paper will focus on the performance of the first flight model thruster, SN001, and presents an overview of the proto-flight testing environments and data obtained. For this first flight thruster, the proto-flight test sequence involved characterizing the performance of the thruster, in addition to vibration and thermal vacuum testing of the thruster. Between each of these environmental tests, the performance of the thruster was verified, ensuring that the environmental exposures, i.e. vibration and TVAC, did not affect the thruster performance. Specifically, the proto-flight data obtained included discharge chamber, optics and neutralizer performance. Faraday probe and ExB data obtained in the regions downstream of the thruster are presented and used to calculate thrust, and therefore specific impulse and total efficiency. Lastly, data are presented showing how the centroid of the ion beam, assumed to be indicative of the thrust vector location, varies throughout the entire proto-flight test campaign. The proto-flight testing of the NEXT-C PPU is documented in a previously published paper by Bontempo4. Following the proto-flight testing of the thruster, the thruster and its PPU successfully completed a System Integrated Test (SIT) tailored to the DART Mission. After the completion of the proto-flight testing, the SN001 thruster and SN002 PPU were delivered to APL for use on the DART mission.

Ion thruster↗
NASA NTRSDate not supplied

High-Propellant Throughput Sub-kW Electric Propulsion System for Deep Space Science and Exploration

The National Aeronautics and Space Administration (NASA) is maturing high-propellant throughput sub-kilowatt electric propulsion technologies to enable small spacecraft deep space science and exploration missions with high delta-v requirements. The pathfinder model (PM) propulsion system consists of the H71M-PM Hall-effect thruster, a breadboard 1-kW power processing unit (PPU), and a propellant flow control system. The propulsion system requirements balance the needs of various high delta-v NASA and commercial industry mission concepts to achieve a design that both enables a variety of NASA small spacecraft deep space missions, while remaining viable for select commercial applications. The H71M-PM thruster has completed performance characterization and three 500-h short duration wear tests (SDWT). The propulsion system provides stable thrust generation over a wide range of operating conditions from 200 W to 1 kW, and 200 V to 400 V. The thruster has demonstrated a thrust as high as 68 mN at 300 V and 1 kW. The thruster has similarly demonstrated a specific impulse of 1850 s at 400 V and 1 kW. Key surfaces were machined between each SDWT to simulate accelerated discharge channel and pole cover erosion. Profilometry scans across masked pole cover surfaces were conducted to determine erosion rates. SDWT results support that a target thruster lifetime of 14 kh with 50% margin is achievable. Component testing has demonstrated propellant azimuthal flow uniformity better than ± 2 percent of the nominal value, azimuthal magnetic field uniformity better than ± 0.5 percent of the nominal value, and cathode heater cycle testing to greater than 30,000 cycles. Propulsion system integrated system testing is planned to use the H71M-PM and a breadboard 1-kW PPU. Pathfinder model test results are now supporting the design of the H71M-EM engineering model thruster. A second-generation breadboard PPU has been fabricated and is currently under test. NASA has made these technologies available to U.S. industry through a no cost, nonexclusive license agreement.

Hall↗
DOE OSTI2021

Spallation Neutron Source Proton Power Upgrade Low-Level RF Control System Development

The Proton Power Upgrade (PPU) Project is approved for the Spallation Neutron Source at Oak Ridge National Laboratory and will double the proton beam power capability from 1.4 MW to 2.8 MW with 2 MW beam power available to the first target station. A second target station is planned and will utilize the remaining beam power in the future. The proton power increase will be supported with the addition of twenty-eight new superconducting cavities powered by 700 kW peak power klystrons to increase beam energy while increases to the beam current will be done with a combination of existing RF margin, and DTL HPRF upgrades. The original low-level RF control system has proven to be reliable over the past 15 years of operations, but obsolescence issues mandate a replacement system be developed for the PPU project. The replacement system is realized in a µTCA.4 platform using a combination of commercial off-the-shelf boards and custom hardware to support the requirements of PPU. This paper presents the prototype hardware, firmware, and software development activities along with preliminary testing results of the new system.

Crofford, Mark↗
NASA NTRS2014

Miniaturized Power Processing Unit Study: A Cubesat Electric Propulsion Technology Enabler Project

This study evaluates High Voltage Power Processing Unit (PPU) technology and driving requirements necessary to enable the Microfluidic Electric Propulsion technology research and development by NASA and university partners. This study provides an overview of the state of the art PPU technology with recommendations for technology demonstration projects and missions for NASA to pursue.

High Voltage Power Processing Unit↗
NASA NTRS1979

Preliminary results of the mission profile life test of a 30 cm Hg bombardment thruster

The paper deals with some preliminary results of the Mission Profile Life Test planned to conduct a program of long-term test segments of 30-cm diameter thrusters and power processing units under computer control. Thruster performance data and other operational characteristics taken at various times during a test segment are compared and the results are evaluated in light of the life-timing mechanisms. Thruster control algorithms are also presented. The first test segment completed 2700 hr of a planned 4000 hr test with a J-series 30-cm thruster. The last 1600 hr used a functional model power processing unit (PPU) operated in vacuum. The thruster-PPU was controlled by a computer with software developed to control start-ups, throttling, and variety of off-normal conditions.

Bechtel, R. T.↗
NASA NTRS1986

Resistojet- and arcjet-propulsion power processing

Power-processing unit (PPU) designs for resistojet and arcjet propulsion systems were developed. Various PPU power converter and power circuit technologies were considered. Arcjet, resistojet and chemical propulsion system performance were compared. Significant propellant mass reductions are enabled with electric propulsion.

Palaszewski, Bryan↗