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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 865 records · Page 48
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Toroidal modeling of thermal particle drift kinetic effects and sub-sonic plasma flow on internal kink mode

The stability of the n = 1 ( n is the toroidal mode number) internal kink mode in a tokamak plasma is numerically investigated, utilizing the full toroidal, ideal magnetohydrodynamic (MHD) code MARS-F [Y. Q. Liu et al. , Phys. Plasmas 7, 3681 (2000)] and the nonperturbative MHD-kinetic hybrid code MARS-K [Y. Liu et al. , Phys. Plasmas 15, 112503 (2008)]. This study focuses on two physics effects: the sheared toroidal flow of plasma and the drift kinetic effects from thermal particles (ions and electrons) on the internal kink instability. Within the subsonic flow assumption, the flow and flow shear effects on the internal kink are generally weak, but the kinetic effects can be strong. A significant reduction in the mode growth rate is predicted by the nonperturbative MHD-kinetic hybrid computations, when the precessional drift resonance contributions from both particle species are included and when the mode is not too strongly unstable according to the fluid theory. The stabilization/destabilization of sheared toroidal flow depends on the radial location of the local flow shear. Strong destabilization (stabilization) occurs when a negative (positive) flow shear is located near the q = 1 rational surface.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2012

RESOLVING THE INNER JET STRUCTURE OF 1924-292 WITH THE EVENT HORIZON TELESCOPE

We present the first 1.3 mm (230 GHz) very long baseline interferometry model image of an active galactic nucleus (AGN) jet using closure phase techniques with a four-element array. The model image of the quasar 1924-292 was obtained with four telescopes at three observatories: the James Clerk Maxwell Telescope on Mauna Kea in Hawaii, the Arizona Radio Observatory's Submillimeter Telescope in Arizona, and two telescopes of the Combined Array for Research in Millimeter-wave Astronomy in California in 2009 April. With the greatly improved resolution compared with previous observations and robust closure phase measurement, the inner jet structure of 1924-292 was spatially resolved. The inner jet extends to the northwest along a position angle of -53 Degree-Sign at a distance of 0.38 mas from the tentatively identified core, in agreement with the inner jet structure inferred from lower frequencies, and making a position angle difference of {approx}80 Degree-Sign with respect to the centimeter jet. The size of the compact core is 0.15 pc with a brightness temperature of 1.2 Multiplication-Sign 10{sup 11} K. Compared with those measured at lower frequencies, the low brightness temperature may argue in favor of the decelerating jet model or particle-cascade models. The successful measurement of closure phase paves the way for imaging and time resolving Sgr A* and nearby AGNs with the Event Horizon Telescope.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Applied metrology in the production of superconducting model magnets for particle accelerators

The production of superconducting magnets for particle accelerators involves high precision assemblies and tight tolerances, in order to achieve the requirements for their appropriate performance. It is therefore essential to have a strict control and traceability over the geometry of each component of the system, and also to be able to compensate possible inherent deviations coming from the production process.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

A Model of Airborne Particle Removal by a Liquid Drop Spray

The removal of airborne particles by liquid drops is an important atmospheric and industrial process. In the atmospheric science literature, it is variously referred to as “precipitation scavenging,” “wet deposition,” or “ rain out” and has been extensively studied for its role in the formation of clouds and the removal of atmospheric pollutants (Pruppacher et al. 1983; Slinn 1984; Pruppacher and Klett 2010).

42 ENGINEERING↗
NASA NTRS1982

Observation and modeling of energetic particles at synchronous orbit on July 29, 1977

In the twelve hours following a worldwide storm, there was a series of at least four magnetospheric substorms, the last and largest of which exhibited an expansion phase onset at approximately 1200 UT. Data from six spacecraft in three general local time groupings (0300, 0700, and 1300 LT) were examined and vector magnetic field data and energetic electron and ion data from approximately 15 keV to 2 MeV were employed.

Baker, D. N.↗