Engineering topics

Vanhoven, Gerard

Publications and source records attributed to Vanhoven, Gerard.

4 records

NASA NTRS1992

Dynamic formation and magnetic support of loop or arcade prominences

The results of model dynamic simulations of the formation and support of a narrow prominence at the apex of a coronal magnetic loop or arcade are described. The condensation process proceeds via an initial radiative cooling and pressure drop, and a secondary siphon flow from the dense chromospheric ends. The antibuoyancy effect as the prominence forms causes a bending of a confining magnetic field, which propagates toward the semirigid ends of the magnetic loop. Thus, a wide magnetic 'hammock' or well (of a normal polarity Kippenhahn-Schlueter type) is formed, which supports the prominence at or near the field apex.

Vanhoven, Gerard↗

NASA NTRS1992

Research in solar plasma theory

The main thrust and significance of our research results are presented. The topics covered include: (1) coronal structure and dynamics; (2) coronal heating; (3) filament formation; and (4) flare energy release.

Vanhoven, Gerard↗

NASA NTRS1992

Plasma dynamics and energetics in the solar atmosphere

Prominence condensation and support, the dynamics of coronal loops, and streamer structure and disconnection are briefly discussed. Prominence condensation and magnetic levitation in a coronal loop and simulations of coronal disconnection events are discussed.

Vanhoven, Gerard↗

NASA NTRS1986

The growth of radiative filamentation modes in sheared magnetic fields

Observations of prominences show them to require well-developed magnetic shear and to have complex small-scale structure. Researchers show here that these features are reflected in the results of the theory of radiative condensation. Researchers studied, in particular, the influence of the nominally negligible contributions of perpendicular (to B) thermal conduction. They find a large number of unstable modes, with closely spaced growth rates. Their scale widths across B show a wide range of longitudinal and transverse sizes, ranging from much larger than to much smaller than the magnetic shear scale, the latter characterization applying particularly in the direction of shear variation.

Vanhoven, Gerard↗