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Results for “Joule heating”

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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Joule-heating power dissipation in a type-II superconductor tube.

The theoretical analysis of the Joule-heating power density in a specific hollow cylinder of a NbZr superconductor is presented. It is seen that the power density, which is the primary source of internal heating neglecting localized annihilation heating, can have a very complicated behavior, especially in the circular region. Rough estimates of the relative temperature changes are made, and the locations at which instabilities are more likely to initiate are considered.

Urban, E. W.↗
NASA NTRS1984

Acceleration of runaway electrons and Joule heating in solar flares

The electric field acceleration of electrons out of a thermal plasma and the simultaneous Joule heating of the plasma are studied. Acceleration and heating timescales are derived and compared, and upper limits are obtained on the acceleration volume and the rate at which electrons can be accelerated. These upper limits, determined by the maximum magnetic field strength observed in flaring regions, place stringent restrictions upon the acceleration process. The role of the plasma resistivity in these processes is examined, and possible sources of anomalous resistivity are summarized. The implications of these results for the microwave and hard X-ray emission from solar flares are examined.

Holman, G. D.↗
NASA NTRS1985

Acceleration of runaway electrons and Joule heating in solar flares

The electric field acceleration of electrons out of a thermal plasma and the simultaneous Joule heating of the plasma are studied. Acceleration and heating timescales are derived and compared, and upper limits are obtained on the acceleration volume and the rate at which electrons can be accelerated. These upper limits, determined by the maximum magnetic field strength observed in flaring regions, place stringent restrictions upon the acceleration process. The role of the plasma resistivity in these processes is examined, and possible sources of anomalous resistivity are summarized. The implications of these results for the microwave and hard X-ray emission from solar flares are examined.

Holman, G. D.↗
NASA NTRS1975

Circulation in the high-latitude thermosphere due to electric fields and Joule heating

Electric fields in the earth's upper atmosphere are capable of setting the neutral atmosphere in motion via ion-neutral collisions as well as pressure gradients from resultant Joule heating. By means of simple models for the high-latitude thermosphere and electric fields a simplified set of coupled equations is solved which show that moderate electric fields, when present for a period of several hours, are capable of displacing the neutral atmosphere of the order of 50 km in the vertical, a few hundred kilometers in the north-south direction and over 1000 km in the east-west direction.

Heaps, M. G.↗
NASA NTRS1989

Joule heating and runaway electron acceleration in a solar flare

The hard and soft x ray and microwave emissions from a solar flare (May 14, 1980) were analyzed and interpreted in terms of Joule heating and runaway electron acceleration in one or more current sheets. It is found that all three emissions can be generated with sub-Dreicer electric fields. The soft x ray emitting plasma can only be heated by a single current sheet if the resistivity in the sheet is well above the classical, collisional resistivity of 10(exp 7) K, 10(exp 11)/cu cm plasma. If the hard x ray emission is from thermal electrons, anomalous resistivity or densities exceeding 3 x 10(exp 12)/cu cm are required. If the hard x ray emission is from nonthermal electrons, the emissions can be produced with classical resistivity in the current sheets if the heating rate is approximately 4 times greater than that deduced from the soft x ray data (with a density of 10(exp 10)/cu cm in the soft x ray emitting region), if there are at least 10(exp 4) current sheets, and if the plasma properties in the sheets are characteristic of the superhot plasma observed in some flares by Lin et al., and with Hinotori. Most of the released energy goes directly into bulk heating, rather than accelerated particles.

Holman, Gordon D.↗
NASA NTRS1990

Polar thermospheric Joule heating, and redistribution of recombination energy in the upper mesosphere

Kellogg (1961), suggested that transport of atomic oxygen from the summer into the winter hemisphere and subsequent release of energy by three body recombination, O+O+N2 yields O2+N2+E, may contribute significantly to the so-called mesopause temperature anomaly. Earlier model calculations have shown that Kellogg's mechanism produces about a 10-percent increase in the temperature from summer to winter at 90 km. This process, however, is partly compensated by differential heating from absorption of UV radiation associated with dissociation of O2. In the auroral region of the thermosphere, there is a steady energy dissipation by Joule heating causing a redistribution and depletion of atomic oxygen due to wind-induced diffusion. With the removal of O, latent chemical energy normally released by three body recombination is also removed, and the result is that the temperature decreases by almost 2 percent near 90 km. Through dynamic feedback, this process reduces the depletion of atomic oxygen by about 25 percent and the temperature perturbation in the exosphere from 10 to 7 percent at polar latitudes. Under the influence of the internal dynamo interaction, the prevailing zonal circulation in the upper thermosphere changes direction when the redistribution of recombination energy is considered.

Mayr, H. G.↗
NASA NTRS1986

Joule heating and field-aligned currents: Preliminary results from DE-2

There are three main processes by which energy is transferred from the magnetosphere to the thermosphere: (1) charge exchange of the ring current particles; (2) precipitation of charged particles; and (3) joule dissipation by the magnetosphere-ionosphere current systems. The importance of this last process has been recognized and the rate of joule heating has been estimated by many workers. Observations of the electric (E) and magnetic (B) fields from Dynamics Explorer Satellite 2 are providing a new set of data on field-aligned currents. One of the remarkable features found in these observations is the high correlation between an orthogonal pair of the E and B field components. In recent years, observational data have accrued concerning the relationship between the interplanetary magnetic field and the size of the polar cap and also about the evolution of a substorm or a magnetic storm. It is suggested that these findings be incorporated in future model calculations.

Sugiura, M.↗
NASA NTRS1980

Joule heating of Io's ionosphere by unipolar induction currents

Electrical induction in Io's ionosphere, due to the corotating plasma bound to the Jovian magnetosphere, is one possible source for the attainment of the high temperatures suggested by the large scale height of Io's ionosphere. Unipolar induction models are constructed to calculate ionospheric joule heating numerically, whose heating rates lie between 10 to the -9th and 10 to the -8th W/cu m. The binding and coupling of the ionosphere is due to the dense, and possibly ionized, neutral SO2 atmosphere, and there appears to be no need to postulate the existence of an intrinsic Ionian magnetic field in order to retain the observed ionnosphere.

Herbert, F.↗
NASA NTRS1979

Joule heating in the high-latitude mesosphere

The contribution made by Joule dissipation to heating of the daytime high-latitude upper mesosphere is discussed. During solar proton precipitation events in regions of large electric fields, Joule dissipation can be substantially larger than the local solar heating rate. Altitude profiles of Joule dissipation are presented for the polar cleft region for the August 4, 1972, solar proton event.

Banks, P. M.↗
NASA NTRS1982

Relations between the Birkeland currents, the auroral electrojet indices and high latitude Joule heating

Field-aligned currents were postulated by Birkeland (1908) to explain the magnetic perturbations in the auroral zone. Theoretical models have been developed to examine the effect of these currents on the ionosphere. These models, in general, involve very extensive computer programs, and it is difficult to see how their very complicated boundary conditions and assumptions affect the relationships between the Birkeland currents and magnetic activity. In the present investigation, a simplified analysis is used to study the average behavior of the large-scale ionospheric current paths and to examine the interrelationships of various parameters. The relationship of the parameters of the current deposition regions to the magnetic indices is investigated along with the polar cap potential. Attention is given to the experimental values of coefficients, and relations between the Birkeland current densities, current intensities, currents, and the AL, AU, AE indices are discussed.

Nisbet, J. S.↗
NASA NTRS1999

On Relationships Between Horizontal Velocity Structure and Thermal Ion Upwellings at High Latitudes

Recent studies indicate that the vertical velocity of F region ion upwellings cannot be explained by frictional heating in the horizontal plane alone but requires additional energization sources. Processes involving velocity shear have recently been put forward as alternate mechanisms that can provide the energization in regions of smaller convection speeds. Studies show that structured flows can also give rise to significant upwelling of ions by seeding plasma waves that can potentially cause ion heating while Joule heating is relatively small. We provide a statistical analysis of the Dynamics Explorer 2 vertical and horizontal ion drift measurements that show further evidence for the significance of plasma wave energization process in regions of varying levels of Joule heating.

Kivanc, O.↗
NASA NTRSDate not supplied

Conceptual Design of a Test Section for a Cryogenic Transfer Line Experiment

This project presents the development of a comprehensive computer-aided design (CAD) model for the Transfer Line test section, which is an upcoming test module for the Flow Boiling and Condensation Experiment (FBCE) aboard the International Space Station. The FBCE aims to serve as the primary platform to study two-phase flow in microgravity, and the Transfer Line module aims to utilize its existing hardware to study cryogenic chilldown; a critical component of cryogenic propellant transfer in space. The CAD model was created using SolidWorks software and includes the test section’s main components: a heat transfer line, a flow visualization line, insulation, high-speed visible imaging, and infrared imaging. The heat transfer line primarily consists of a stainless steel tube that will be heated via Joule heating. The flow visualization line consists of segmented Indium-Titanium-Oxide coated sapphire tubes, which allow for visualization of flow regimes by high-speed and infrared cameras, similar thermal properties as the stainless steel tube, and Joule heating via the ITO coating resistance. Polyether Ether Ketone was used to insulate and encapsulate the two sections. High-speed visible imaging and infrared imaging were also incorporated to view the propagation of fluid during inverted annular flow and map out the thermal profile of the ITO-coated sapphire tube. This model serves as the guiding concept design for the Transfer Line project and will assist the project team during future safety reviews and concept design reviews. Overall, this work is significant in two-phase flow research and offers a promising path towards an established facility for cryogenic transfer line research in microgravity.

Flow boiling↗
NASA NTRS1990

Energy balance in the solar transition region. I - Hydrostatic thermal models with ambipolar diffusion

The energy balance in the lower transition region is analyzed by constructing theoretical models which satisfy the energy balance constraint. The energy balance is achieved by balancing the radiative losses and the energy flowing downward from the corona. This energy flow is mainly in two forms: conductive heat flow and hydrogen ionization energy flow due to ambipolar diffusion. Hydrostatic equilibrium is assumed, and, in a first calculation, local mechanical heating and Joule heating are ignored. In a second model, some mechanical heating compatible with chromospheric energy-balance calculations is introduced. The models are computed for a partial non-LTE approach in which radiation departs strongly from LTE but particles depart from Maxwellian distributions only to first order. The results, which apply to cases where the magnetic field is either absent, or uniform and vertical, are compared with the observed Lyman lines and continuum from the average quiet sun. The approximate agreement suggests that this type of model can roughly explain the observed intensities in a physically meaningful way, assuming only a few free parameters specified as chromospheric boundary conditions.

Fontenla, J. M.↗
NASA NTRS2011

Direct EPP Affects on the Middle Atmosphere

Energetic precipitating particles (EPPs) can cause significant direct constituent changes in the mesosphere and stratosphere (middle atmosphere) during certain periods. Both protons and electrons can influence the polar middle atmosphere through ionization and dissociation processes. EPPs can enhance HOx (H, OH, HO2) through the formation of positive ions followed by complex ion chemistry and NOx (N, NO, NO2) through the dissociation of molecular nitrogen. The HOx increases result in direct ozone destruction in the mesosphere and upper stratosphere via several catalytic loss cycles. Such middle atmospheric HOx-caused ozone loss is rather short-lived due to the relatively short lifetime (hours) of the HOx constituents. The NOx family has a considerably longer lifetime than the HOx family and can also lead to catalytic ozone destruction. EPP-caused enhancements of the NOx family can affect ozone directly, if produced in the stratosphere. Ozone decreases from the EPPs lead to a reduction in atmospheric heating and, subsequent atmospheric cooling. Conversely, EPPs can cause direct atmospheric heating through Joule heating. Measured HOx constituents OH and HO2 showed increases due to solar protons. Observed NOx constituents NO and NO2 were enhanced due to both solar protons and precipitating electrons. Other hydrogen- and nitrogen-ocntaining constituents were also measured to be directly influenced by EPPs, including N2O, HNO3, HO2NO2, N2OS, H2O2, ClONO2, HCl, and HOCl. Observed constituents ClO and CO were directly affected by EPPs as well. Many measurements indicated significant direct ozone decreases. A significant number of satellites housed instruments, which observed direct EPP-caused atmospheric effects, including Nimbus 4 (BUV), Nimbus 7 (SBUV), several NOAA platforms (SBUV/2), SME, UARS (HALOE, CLAES), SCISAT-1 (ACE-FTS), Odin (OSIRIS), Envisat-l (GOMOS, MIPAS, SCIAMACHY), and Aura (MLS). Measurements by rockets and ground-based radar also indicated EPP direct impacts. Atmospheric models have been used with some success in predicting the direct EPP impacts on the mesosphere and stratosphere. A review of the observed direct effects of EPP on the middle atmosphere will be given in this presentation.

Jackman, Charles H.↗