Transition of slow shocks to fast shocks

Conference · Thu Jun 01 04:00:00 EDT 1995

OSTI ID:266947

Whang, Y C

As a CME pushes its way through preceding slower solar wind, large disturbances in the interaction region may evolve to form transient MHD shocks. The shocks can be slow shocks in the coronal space but they appear as fast shocks near 1 AU. The authors use a polytropic MHD model to study the transition of slow shocks to fast shocks in an interaction region sandwiched between a faster solar wind and a slower solar wind near the equatorial plane. The polytropic index controls the radial increase of Beta outside the interaction region. The transition process is attributed chiefly to the increase of Beta and theta to a lesser degree to the radial increase of the shock angle 0. Under the initial condition of small Beta and theta near 0.1 AU, the interaction region evolves to form a pair of slow shocks inside 0.15 AU. As the interaction region convects outward. the increases of B and theta cause a transition of the shock system between 0.15 and 0.3 AU from a slow shock pair to a double shock pair consisting of both slow and fast shocks. As the system moves outward, and Beta continues to increase, the fast shock grows stronger, and the slow shock becomes weaker. Eventually. the slow shocks fade away, and the shock system finally evolves to a pair of fast shocks. Parametric studies of the transition process are carried out for shocks formed over a wide range of disturbances.

• Research Organization: Jet Propulsion Lab., Pasadena, CA (United States)
• OSTI ID: 266947
• Report Number(s): N--96-24651; NASA-CR--199940; JPL-PUBL--95-13; NAS--1.26:199940; NIPS--95-06571; CONF-9506256--
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
BETA RATIO
MAGNETOHYDRODYNAMICS
PHASE TRANSFORMATIONS
SHOCK WAVES
SOLAR WIND