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J. Boise Pearson

Bio: J. Boise Pearson is an academic researcher from Marshall Space Flight Center. The author has contributed to research in topics: Propulsion & Stirling cycle. The author has an hindex of 4, co-authored 21 publications receiving 53 citations.

Papers
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Journal ArticleDOI
TL;DR: In this article, a thrust stand calibration technique for use in testing repetitively-pulsed electric thrusters for in-space propulsion has been developed and tested using a modified hanging pendulum thrust stand.
Abstract: A thrust stand calibration technique for use in testing repetitively-pulsed electric thrusters for in-space propulsion has been developed and tested using a modified hanging pendulum thrust stand. In the implementation of this technique, current pulses are applied to a solenoidal coil to produce a pulsed magnetic field that acts against the magnetic field produced by a permanent magnet mounted to the thrust stand pendulum arm. The force on the magnet is applied in this non-contact manner, with the entire pulsed force transferred to the pendulum arm through a piezoelectric force transducer to provide a time-accurate force measurement. Modelingof thependulumarm dynamics reveals thatafter an initialtransientinthruststand motion thequasisteady average deflection of the thrust stand arm away from the unforced or ‘zero’ position can be related to the average applied force through a simple linear Hooke’s law relationship. Modeling demonstrates that this techniqueis universally applicableexcept when the pulsingperiod is increased to the pointwhere it approaches the period of natural thrust stand motion. Calibration data were obtained using a modified hanging pendulum thrust stand previously used for steady-state thrust measurements. Data were obtained for varying impulse bit at constant pulse frequency and for varying pulse frequency. The two data sets exhibit excellent quantitative agreement with each other as the constant relating average deflection and average thrust match within the errors on the linear regression curve fit of the data. Quantitatively, the error on the calibration coefficient is roughly 1% of the coefficient value.

17 citations

25 Jul 2010
TL;DR: In this paper, the first attempt at powering a free-piston Stirling engine with a pumped liquid metal heat source was made, which is a major milestone towards demonstrating technical feasibility.
Abstract: As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1 kW class free-piston Stirling convertors was modified to operate with a NaK liquid metal pumped loop for thermal energy input. This was the first-ever attempt at powering a free-piston Stirling engine with a pumped liquid metal heat source and is a major FSP project milestone towards demonstrating technical feasibility. The tests included performance mapping the convertors over various hot and cold-end temperatures, piston amplitudes and NaK flow rates; and transient test conditions to simulate various start-up and fault scenarios. Performance maps of the convertors generated using the pumped NaK loop for thermal input show increases in power output over those measured during baseline testing using electric heating. Transient testing showed that the Stirling convertors can be successfully started in a variety of different scenarios and that the convertors can recover from a variety of fault scenarios.

10 citations

25 Jul 2010
TL;DR: In this paper, an annular linear induction pump was tested over a range of conditions, including frequencies of 33, 36, 39, and 60 Hz, liquid metal temperatures from 125 to 525 C, and input voltages from 5 to 120 V. The maximum efficiency measured during testing was slightly greater than 6%.
Abstract: Results of performance testing of an annular linear induction pump are presented. The pump electromagnetically pumps liquid metal through a circuit specially designed to allow for quantification of the performance. Testing was conducted over a range of conditions, including frequencies of 33, 36, 39, and 60 Hz, liquid metal temperatures from 125 to 525 C, and input voltages from 5 to 120 V. Pump performance spanned a range of flow rates from roughly 0.16 to 5.7 L/s (2.5 to 90 gpm), and pressure head less than 1 to 90 kPa (less than 0.145 to 13 psi). The maximum efficiency measured during testing was slightly greater than 6%. The efficiency was fairly insensitive to input frequency from 33 to 39 Hz, and was markedly lower at 60 Hz. In addition, the efficiency decreased as the NaK temperature was raised. The performance of the pump operating on a variable frequency drive providing 60 Hz power compared favorably with the same pump operating on 60 Hz power drawn directly from the electrical grid.

4 citations

Proceedings ArticleDOI
01 Feb 2007
TL;DR: In this article, a water-based shielding system is investigated for use on initial lunar surface power systems, which may lower overall cost and simplify operations in the setup and handling of the system.
Abstract: A water based shielding system is being investigated for use on initial lunar surface power systems. The use of water may lower overall cost (as compared to development cost for other materials) and simplify operations in the setup and handling. The thermal hydraulic performance of the shield is of significant interest. The mechanism for transferring heat through the shield is natural convection. Natural convection in a representative lunar surface reactor shield design is evaluated at various power levels in the Water Shield Testbed (WST) at the NASA Marshall Space Flight Center. The experimental data from the WST is used to anchor a CFD model. Performance of a water shield on the lunar surface is then predicted by CFD models anchored to test data. The accompanying viewgraph presentation includes the following topics: 1) Testbed Configuration; 2) Core Heater Placement and Instrumentation; 3) Thermocouple Placement; 4) Core Thermocouple Placement; 5) Outer Tank Thermocouple Placement; 6) Integrated Testbed; 7) Methodology; 8) Experimental Results: Core Temperatures; 9) Experimental Results; Outer Tank Temperatures; 10) CFD Modeling; 11) CFD Model: Anchored to Experimental Results (1-g); 12) CFD MOdel: Prediction for 1/6-g; and 13) CFD Model: Comparison of 1-g to 1/6-g.

4 citations

01 Mar 2011
TL;DR: In this paper, a pair of commercially available 1-kW-class free-piston Stirling convertors were modified to operate with a NaK (sodium (Na) and potassium (K)) liquid metal pumped loop for thermal energy input.
Abstract: As a step towards development of Stirling power conversion for potential use in Fission Surface Power (FSP) systems, a pair of commercially available 1-kW-class free-piston Stirling convertors were modified to operate with a NaK (sodium (Na) and potassium (K)) liquid metal pumped loop for thermal energy input. This was the first-ever attempt at powering a free-piston Stirling engine with a pumped liquid metal heat source and is a major FSP project milestone towards demonstrating technical feasibility. The convertors were successfully tested at the Marshall Space Flight Center (MSFC) from June 6 through July 14, 2009. The convertors were operated for a total test time of 66 hr and 16 min. The tests included (a) performance mapping the convertors over various hot- and cold-end temperatures, piston amplitudes, and NaK flow rates and (b) transient test conditions to simulate various startup (i.e., low-, medium-, and high-temperature startups) and fault scenarios (i.e., loss of heat source, loss of NaK pump, convertor stall, etc.). This report documents the results of this testing

4 citations


Cited by
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Book ChapterDOI
28 Jan 2005
TL;DR: The Q12-40 density: ρ ((kg/m) specific heat: Cp (J/kg ·K) dynamic viscosity: ν ≡ μ/ρ (m/s) thermal conductivity: k, (W/m ·K), thermal diffusivity: α, ≡ k/(ρ · Cp) (m /s) Prandtl number: Pr, ≡ ν/α (−−) volumetric compressibility: β, (1/K).
Abstract: Geometry: shape, size, aspect ratio and orientation Flow Type: forced, natural, laminar, turbulent, internal, external Boundary: isothermal (Tw = constant) or isoflux (q̇w = constant) Fluid Type: viscous oil, water, gases or liquid metals Properties: all properties determined at film temperature Tf = (Tw + T∞)/2 Note: ρ and ν ∝ 1/Patm ⇒ see Q12-40 density: ρ ((kg/m) specific heat: Cp (J/kg ·K) dynamic viscosity: μ, (N · s/m) kinematic viscosity: ν ≡ μ/ρ (m/s) thermal conductivity: k, (W/m ·K) thermal diffusivity: α, ≡ k/(ρ · Cp) (m/s) Prandtl number: Pr, ≡ ν/α (−−) volumetric compressibility: β, (1/K)

636 citations

Journal ArticleDOI
24 Jul 2020
TL;DR: An inductive pulsed plasma thruster (IPPT) as discussed by the authors operates by pulsing high current through an inductor, typically a coil of some type, producing an electromagnetic field that drives current in a plasma, accelerating it to high speed.
Abstract: An inductive pulsed plasma thruster (IPPT) operates by pulsing high current through an inductor, typically a coil of some type, producing an electromagnetic field that drives current in a plasma, accelerating it to high speed. The IPPT is electrodeless, with no direct electrical connection between the externally applied pulsed high-current circuit and the current conducted in the plasma. Several different configurations were proposed and tested, including those that produce a plasma consisting of an accelerating current sheet and those that use closed magnetic flux lines to help confine the plasma during acceleration. Specific impulses up to 7000 s and thrust efficiencies over 50% have been measured. The present state-of-the-art for IPPTs is reviewed, focusing on the operation, modeling techniques, and major subsystems found in various configurations. Following that review is documentation of IPPT technology advancement paths that were proposed or considered.

30 citations

Proceedings ArticleDOI
01 Mar 2009
TL;DR: The Fission Surface Power Systems project (FSPSP) as discussed by the authors has focused on subscale component and subsystem demonstrations to address the feasibility of a low-risk, low-cost approach to space nuclear power for surface missions.
Abstract: Power is a critical consideration in planning exploration of the surfaces of the Moon, Mars, and places beyond Nuclear power is an important option, especially for locations in the solar system where sunlight is limited or environmental conditions are challenging (eg, extreme cold, dust storms) NASA and the Department of Energy are maintaining the option for fission surface power for the Moon and Mars by developing and demonstrating technology for a fission surface power system The Fission Surface Power Systems project has focused on subscale component and subsystem demonstrations to address the feasibility of a low-risk, low-cost approach to space nuclear power for surface missions Laboratory demonstrations of the liquid metal pump, reactor control drum drive, power conversion, heat rejection, and power management and distribution technologies have validated that the fundamental characteristics and performance of these components and subsystems are consistent with a Fission Surface Power preliminary reference concept In addition, subscale versions of a non-nuclear reactor simulator, using electric resistance heating in place of the reactor fuel, have been built and operated with liquid metal sodium-potassium and helium/xenon gas heat transfer loops, demonstrating the viability of establishing system-level performance and characteristics of fission surface power technologies without requiring a nuclear reactor While some component and subsystem testing will continue through 2011 and beyond, the results to date provide sufficient confidence to proceed with system level technology readiness demonstration To demonstrate the system level readiness of fission surface power in an operationally relevant environment (the primary goal of the Fission Surface Power Systems project), a full scale, 1/4 power Technology Demonstration Unit (TDU) is under development The TDU will consist of a non-nuclear reactor simulator, a sodium-potassium heat transfer loop, a power conversion unit with electrical controls, and a heat rejection system with a multi-panel radiator assembly Testing is planned at the Glenn Research Center Vacuum Facility 6 starting in 2012, with vacuum and liquid-nitrogen cold walls to provide simulation of operationally relevant environments A nominal two-year test campaign is planned including a Phase 1 reactor simulator and power conversion test followed by a Phase 2 integrated system test with radiator panel heat rejection The testing is expected to demonstrate the readiness and availability of fission surface power as a viable power system option for NASA's exploration needs In addition to surface power, technology development work within this project is also directly applicable to in-space fission power and propulsion systems

20 citations

Journal ArticleDOI
TL;DR: In this paper, a robust stand for directly measuring pulsed thrust from micro-thrusters is presented, which can test single and multiple thrusters with a total mass of up to 10 kg and was found to be capable of resolving impulse bits between 0.27?600 n and 2.4% error in the optimal deflection range.
Abstract: A robust stand for directly measuring pulsed thrust from micro-thrusters is presented. The method of electrostatic discs for in situ calibration was improved upon and simplified to allow convenient and accurate thrust measurement. The novel use of frictionless liquid gallium metal power interfaces for ?N-level force measurement stands was also demonstrated. A series of detailed verification tests were performed to characterize the thrust stand?s overall operating range and accuracy. The stand can test single and multiple thrusters with a total mass of up to 10?kg and was found to be capable of resolving impulse bits between 0.27?600??Ns with 2?4% error in the optimal deflection range. Demonstration of the thrust stand?s capability and resilience to electromagnetic interference was accomplished by performing lifetime thrust tests on low-power Vacuum-Arc Thrusters operating with three different cathode fuels.

15 citations

Proceedings ArticleDOI
25 Jul 2010
TL;DR: In this paper, three different low-power cylindrical Hall thrusters, which more readily lend themselves to miniaturization and low power operation than a conventional (annular) Hall thruster, are compared to evaluate the propulsive performance of each.
Abstract: Three different low-power cylindrical Hall thrusters, which more readily lend themselves to miniaturization and low-power operation than a conventional (annular) Hall thruster, are compared to evaluate the propulsive performance of each. One thruster uses electromagnet coils to produce the magnetic field within the discharge channel while the others use permanent magnets, promising power reduction relative to the electromagnet thruster. A magnetic screen is added to the permanent magnet thruster to improve performance by keeping the magnetic field from expanding into space beyond the exit of the thruster. The combined dataset spans a power range from 50-350 W. The thrust levels over this range were 1.3-7.3 mN, with thruster efficiencies and specific impulses spanning 3.5-28.7% and 400-1940 s, respectively. The efficiency is generally higher for the permanent magnet thruster with the magnetic screen, while That thruster s specific impulse as a function of discharge voltage is comparable to the electromagnet thruster.

15 citations