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A vacuum ultraviolet spectrophotometric system
The development of a vacuum ultraviolet spectrophotometric system for measuring transmittance and reflectance at variable angles is presented. Using various detectors and sources, the spectrophotometric system has been used for wavelengths from 80 nm to 300 nm with optical components up to 80 mm in diameter. The capability exists to make measurements through the visible range.
Thermal System Upgrade of the Space Environment Simulation Test Chamber
The paper deals with the refurbishing and upgrade of the thermal system for the existing thermal vacuum test facility, the Space Environment Simulator, at NASA's Goddard Space Flight Center. The chamber is the largest such facility at the center. This upgrade is the third phase of the long range upgrade of the chamber that has been underway for last few years. The first phase dealt with its vacuum system, the second phase involved the GHe subsystem. The paper describes the considerations of design philosophy options for the thermal system; approaches taken and methodology applied, in the evaluation of the remaining "life" in the chamber shrouds and related equipment by conducting special tests and studies; feasibility and extent of automation, using computer interfaces and Programmable Logic Controllers in the control system and finally, matching the old components to the new ones into an integrated, highly reliable and cost effective thermal system for the facility. This is a multi-year project just started and the paper deals mainly with the plans and approaches to implement the project successfully within schedule and costs.
Theoretical and experimental studies of the underlying processes and techniques of low pressure measurement Final report
Supressor, pressure, and ionization gauges, getter ion pumps, bakeout procedures, and adsorption in high and ultrahigh vacuum systems
The attainment of clean vacuum with a one- watt refrigerator
One-watt refrigerator used for attaining clean room conditions in vacuum system of space simulator
Extreme vacuum technology including cryosorption, diffusion pump and pressure calibration studies quarterly status report no. 7, 1 feb. - 1 may, 1965
Effectiveness of chemical trap in reducing residual gas in ultrahigh vacuum systems by oil diffusion pump
Evaluating Mass Analyzers as Candidates for Small, Portable, Rugged Single Point Mass Spectrometers for Analysis of Permanent Gases
For Space Shuttle launch safety, there is a need to monitor the concentration of H2, He, O2 and Ar around the launch vehicle. Currently a large mass spectrometry system performs this task, using long transport lines to draw in samples. There is great interest in replacing this stationary system with several miniature, portable, rugged mass spectrometers which act as point sensors which can be placed at the sampling point. Five commercial and two non-commercial analyzers are evaluated. The five commercial systems include the Leybold Inficon XPR-2 linear quadrupole, the Stanford Research (SRS-100) linear quadrupole, the Ferran linear quadrupole array, the ThermoQuest Polaris-Q quadrupole ion trap, and the IonWerks Time-of-Flight (TOF). The non-commercial systems include a compact double focusing sector (CDFMS) developed at the University of Minnesota, and a quadrupole ion trap (UF-IT) developed at the University of Florida. The System Volume is determined by measuring the entire system volume including the mass analyzer, its associated electronics, the associated vacuum system, the high vacuum pump and rough pump. Also measured are any ion gauge controllers or other required equipment. Computers are not included. Scan Time is the time required for one scan to be acquired and the data to be transferred. It is determined by measuring the time required acquiring a known number of scans and dividing by said number of scans. Limit of Detection is determined first by performing a zero-span calibration (using a 10-point data set). Then the limit of detection (LOD) is defined as 3 times the standard deviation of the zero data set. (An LOD of 10 ppm or less is considered acceptable.)
Study of CW gaseous lasers for space communications Semiannual status report, 1 Jul. - 30 Nov. 1966
Helium-xenon continuous wave gas lasers for space communications - testing of ultrahigh vacuum system and cascade pumping techniques
Transmission probability determination with directed mass motion and with mean free path considerations.
Transmission probability describing free molecular flow through vacuum systems obtained via Monte Carlo program
Investigation of kilovolt ion sputtering second quarterly progress report
Kilovolt ion sputtering - electron beam focusing of cesium ion beam, radiation detection in copper atoms, ultrahigh vacuum system construction, and spectrometer pulse height
A Segmented Ion-Propulsion Engine
New design approach for high-power (100-kW class or greater) ion engines conceptually divides single engine into combination of smaller discharge chambers integrated to operate as single large engine. Analogous to multicylinder automobile engine, benefits include reduction in required accelerator system span-to-gap ratio for large-area engines, reduction in required hollow-cathode emission current, mitigation of plasma-uniformity problem, increased tolerance to accelerator system faults, and reduction in vacuum-system pumping speed.
Investigation into Cryogenic Tank Insulation Systems for the Mars Surface Environment
In order to use oxygen that is produced on the surface of Mars from In-Situ production processes in a chemical propulsion system, the oxygen must first be converted from vapor phase to liquid phase and then stored within the propellant tanks of the propulsion system. The oxygen must then be stored in the liquid phase for several years between when the liquefaction operations are initiated and when the ascent stage lifts off the Martian surface. Since the Space Exploration Initiative, NASA has been investing small sums of money into soft vacuum systems for Mars Applications. A study was done into these various insulation systems for soft vacuum insulation, to determine what types of systems might be best to further pursue. Five different architectures or cycles were considered: Aerogel-based multilayer Insulation (MLAI), Space Evacuated Mars Vacuum Jacket (SEMOV) (also known as lightweight vacuum jacket), Load Responsive-Multilayer Insulation, Spray on Foam with MLI, and MLAI in SEMOV. Models of each architecture were developed to give insight into the performance and losses of each of the options. The results were then compared across six categories: Insulation System Mass, Active System Power (both input and heat rejection), Insulation System Cost, Manufacturability, Reliability, and Operational Flexibility. The result was that a trade between reliability and mass was clearly identified. Systems with high mass, also had high perceived reliability; whereas, systems with lower mass and power had a much lower perceived reliability. In the end, the numerical trades of these systems showed nominally identical rankings. As a result it is recommended that NASA focus its Martian insulation development activities on demonstrating and improving the reliability of the lightweight identified systems.
Ionization-Assisted Getter Pumping for Ultra-Stable Trapped Ion Frequency Standards
A method eliminates (or recovers from) residual methane buildup in getter-pumped atomic frequency standard systems by applying ionizing assistance. Ultra-high stability trapped ion frequency standards for applications requiring very high reliability, and/or low power and mass (both for ground-based and space-based platforms) benefit from using sealed vacuum systems. These systems require careful material selection and system processing (cleaning and high-temperature bake-out). Even under the most careful preparation, residual hydrogen outgassing from vacuum chamber walls typically limits the base pressure. Non-evaporable getter pumps (NEGs) provide a convenient pumping option for sealed systems because of low mass and volume, and no power once activated. An ion gauge in conjunction with a NEG can be used to provide a low mass, low-power method for avoiding the deleterious effects of methane buildup in high-performance frequency standard vacuum systems.
The behavior of lubrication system components in a vacuum environment
Lubrication system components behavior in vacuum environment, investigating evaporation, friction, adhesion, wear, etc
Influence of a vacuum environment on friction and lubrication studies
Influence of vacuum system and oxygen partial pressures on friction behavior of metals in sliding contact
Approximating Fluid Flow from Ambient to Very Low Pressures: Modeling ISS Experiments that Vent to Vacuum
Two ISS (International Space Station) experiment payloads will vent a volume of gas overboard via either the ISS Vacuum Exhaust System or the Vacuum Resource System. A system of ducts, valves and sensors, under design, will connect the experiments to the ISS systems. The following tasks are required: Create an analysis tool that will verify the rack vacuum system design with respect to design requirements, more specifically approximate pressure at given locations within the vacuum systems; Determine the vent duration required to achieve desired pressure within the experiment modules; Update the analysis as systems and operations definitions mature.
Electrode surface physics research
Experimental tube design, vacuum system, technique for studying electron and ion emission from cesiated nonrefractory and refractory metals, semiconductors, and insulators
Ultrahigh-Vacuum Sample-Transfer System
Ultrahigh-vacuum (UHV) sample-transfer system developed features short-term (less than 30 minutes) transfer of samples from atmospheric pressure into sample manipulator within UHV analysis system without significantly degrading system pressure. New system is austere approach to sample transfer, involving no automation. Total cost of system is factor of 10 less than commercially available instruments.