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Barnes, C.

Publications and source records attributed to Barnes, C..

26 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Post irradiation effects (PIE) in integrated circuits

Post-irradiation effects (PIE) ranging from normal recovery to catastrophic failure have been observed in integrated circuits during the PIE period. Data presented show failure due to rebound after a 10 krad(Si) dose. In particular, five device types are investigated with varying PIE response. Special attention has been given to the HI1-507A analog multiplexer because its PIE response is extreme. X-ray diffraction has been uniquely employed to measure physical stress in the HI1-507A metallization. An attempt has been made to show a relationship between stress relaxation and radiation effects. All data presented support the current MIL-STD Method 1019.4 but demonstrate the importance of performing PIE measurements, even when mission doses are as low as 10 krad(Si).

Shaw, D. C.↗
NASA NTRS1991

The NASA Microelectronics Space Radiation Effects Program (MSREP) at the Jet Propulsion Laboratory

The primary objective of the Microelectronics Space Radiation Effects Program (MSREP) at the Jet Propulsion Laboratory (JPL) is to assist NASA in the selection of radiation hardened microelectronic parts for insertion in NASA space systems through radiation testing and research. Prior to presenting examples of the research and testing on Single Event Effects (SEE) and Total Ionizing Dose (TID) effects, the space radiation environment and radiation requirements for the CRAFT/Cassini program, a typical JPL space project, are discussed.

Barnes, C.↗
NASA NTRS1991

Overview of fiber optics in the natural space environment

The potential applications of fiber-optic (FO) systems in spacecraft which will be exposed to the space radiation environment are discussed in view of tests conducted aboard the Long-Duration Exposure Facility and the Comet Rendezvous and Asteroid Flyby spacecraft. Attention is given to anticipated trends in the use of FO in spacecraft communications systems. The natural space radiation environment is noted to be far more benign than the military space environment, which encompasses displacement-damage effects due to significant neutron influences.

Barnes, C.↗
NASA NTRS1991

Morphological responses of wheat to changes in phytochrome photoequilibrium

Wheat plants (Triticum aestivum L.) were grown at the same photosynthetic photon flux (PPF), 200 micromoles per square meter per second, but with phytochrome photoequilibrium (phi) values of 0.81, 0.55, and 0.33. Plants grown at phi values of 0.55 and 0.33 tillered 43 and 56%, less compared with plants grown at phi of 0.81. Main culm development (Haun stage) was slightly more advanced at lower values of phi, and leaf sheaths, but not leaf lamina, were longer at lower phi. Dry-mass accumulation was not affected by different levels of phi. Three levels of PPF (100, 200, and 400 micromoles per square meter per second) and two lamp types, metal halide and high pressure sodium, were also tested. Higher levels of PPF resulted in more dry mass, more tillering, and a more advanced Haun stage. There was no difference in plant dry mass or development under metal halide versus high pressure sodium lamps, except for total leaf length, which was greater under high pressure sodium lamps (49.5 versus 44.9 centimeters, P < 0.01).

Non-NASA Center↗
NASA NTRS1987

Weak double layers in the auroral ionosphere

Previous work on the evolution of weak double layers in a hydrogen plasma was extended to include H(+) and O(+) with relative drift. The relative drift between hydrogen and oxygen ions due to a quasi-static parallel electric field gives rise to a strong linear fluid instability which dominates the ion-acoustic mode at the bottom of the auroral acceleration region. This ion-ion instability can modify ion distributions at lower altitudes and the subsequent nonlinear evolution of weak double layers at higher altitudes in the ion-acoustic regime. Ion hole formation can occur for smaller relative electron-ion drifts than seen in previous simulations, due to the hydrogen-oxygen two-stream instability. This results in local modification of the ion distributions in phase space, and a partial filling of the valley between the hydrogen and oxygen peaks, which would be expected at higher altitudes on auroral field lines. The observed velocity diffusion does not necessarily preclude ion hole and double layer formation in hydrogen in the ion-acoustic regime. These simulation results are consistent with the experimentally measured persistence of separate hydrogen and oxygen peaks, and the observation of weak double layers above an altitude of 3000 km on auroral field lines.

Hudson, M. K.↗
NASA NTRS1981

Anomalous dc resistivity and double layers in the auroral ionosphere

There are at least four candidate instabilities which might account for anomalous dc resistivity in the auroral ionosphere. These are: the ion-acoustic instability, the Buneman instability, the ion-cyclotron instability and double layers. A description is given of the results of computer simulations of these four instabilities which suggest that double layers are most likely to be responsible for resistivity in the auroral zone.

Kindel, J. M.↗
NASA NTRS1972

Activity in galaxies and quasars.

Activity in galaxies and quasars is interpreted in terms of plasma processes occurring in the magnetosphere of a certain magnetoid model. This magnetoid comprises a core and an annulus rotating about a common axis with different angular velocities. The magnetic field linking the core to the annulus may begin in an initial current-free state but will be distorted along a sequence of force-free configurations. After a finite differential rotation, the force-free configuration has higher energy than a corresponding open-field configuration. It is conjectured that the transition from the closed configuration to an open configuration will be effected by an MHD eruptive instability, and that such eruptions lead to high-velocity clouds of cool gas identified with clouds producing absorption lines in quasars. It is proposed that minor instabilities of the current sheets are responsible for fluctuations in the nonthermal luminosity and for small-scale radio bursts sometimes observed in galaxies and quasars.

Sturrock, P. A.↗