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Results for “VACUUM CHAMBER”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Laboratory leak tester provides high sensitivity

Detecting unit is capable of measuring leak rates of 10 to the minus 5th power cc/sec or less. Device can be mounted in a carrying case and consists of three vacuum chambers, two pressure gages, and positive seal type control valves.

Hayes, E. G.↗
NASA NTRS1972

Polymeric coatings using electronic excitation

Process has been developed for glow discharge polymerization which is accomplished in inert atmosphere by using vacuum chamber. Polymeric coating, in this type of environment, produces high molecular weight coating polymers that have good stability and are resistant to abrasions and solvents.

Lee, S. M.↗
NASA NTRS1971

Simulated space environment tests on cadmium sulfide solar cells

Cadmium sulfide (Cu2s - CdS) solar cells were tested under simulated space environmental conditions. Some cells were thermally cycled with illumination from a Xenon-arc solar simulator. A cycle was one hour of illumination followed immediately with one-half hour of darkness. In the light, the cells reached an equilibrium temperature of 60 C (333 K) and in the dark the cell temperature dropped to -120 C (153 K). Other cells were constantly illuminated with a Xenon-arc solar simulator. The equilibrium temperature of these cells was 55 C (328 K). The black vacuum chamber walls were cooled with liquid nitrogen to simulate a space heat sink. Chamber pressure was maintained at 0.000001 torr or less. Almost all of the solar cells tested degraded in power when exposed to a simulated space environment of either thermal cycling or constant illumination. The cells tested the longest were exposed to 10.050 thermal cycles.

Clarke, D. R.↗
NASA NTRS1971

Engineering experimental program on the effects of near-space radiation on lithium doped solar cells

The results of an experimental evaluation of the real-time degradation characteristics of lithium-diffused silicon solar cells are reported. A strontium-90 radioisotope was used for simulation of a typical earth-orbital electron environment. The experiment was performed in an ion pump vacuum chamber with samples maintained at -50, +20, +50, and +80 C. Samples were illuminated during the 6-month exposure run with solar cell 1-5 characteristics measured periodically in situ. This 6-month exposure corresponded to a 1 MeV equivalent fluence of approximately 10 to the 14th power electrons/sq cm. Several types of lithium cells were irradiatied and compared directly with conventional N/P cells. The best lithium cells compared favorably with N/P cells, particularly at the higher test temperatures. With a slight improvement of initial performance characteristics, lithium cells appear feasible for 5 to 10 year missions at synchronous altitude. Based on the reported results and those of other irradiation experiments, lithium cells would appear to be superior to N/P cells in proton-dominated earth-orbital environments. Another important conclusion of the effort was that illuminated/loaded cells degrade more rapidly than do dark/unloaded cells. The irradiation experiment provided data of high quality with a high degree of confidence because of the experimental and statistical analysis techniques utilized.

Source record↗
NASA NTRS1972

Advantages of cryopumping with liquid hydrogen instead of helium refrigerators

Open loop hydrogen vaporizers and helium refrigerators are compared for operational complexity, installation and operating cost, and safety requirements. Data from two vacuum chambers using helium refrigerators are used to provide comparative data. In general, the use of hydrogen is attractive in the larger systems, even when extra safety precautions are taken. Emotional resistance to the use of hydrogen because of safety requirements is considered great. However, the experience gained in the handling of large quantities of cryogenics, particularly hydrogen and liquefied natural gases, should be considered in the design of open loop hydrogen cooling systems.

J.W. Anderson↗