Diffusion coefficients of low-energy protons upstream of quasi-parallel interplanetary shocks

Technical Report · Sun Jan 01 04:00:00 EST 1984

OSTI ID:6607317

Van Nes, P; Roelof, E C; Reinhard, R; Sanderson, T R; Wenzel, K P

The diffusion coefficient for low-energy protons upstream of three interplanetary shocks were observed on ISEE-3. The intensity increase as the shock approaches can be fitted by a running exponential, the e-folding time t* of which is assumed to be a direct measure of the diffusion coefficient. The energy dependence of t* close to the shock (0-60 R/sub e/) is derived from the four energy channels covering the range 35-238 keV. The t* in the low-energy channels (less than 100 keV) increases with distance away from the shock. However, t* decreases above 100 keV and roughly beyond 100 Re so that the diffusion coefficient becomes independent of energy. We suggest that the energy independence of t* in a region well upstream of the shock is the result of enhanced parallel scattering through 90 pitch angles for higher energy (larger gyroradius) particles which are more sensitive to variations in the transverse direction of the magnetic field.

• Research Organization: Johns Hopkins Univ., Laurel, MD (USA). Applied Physics Lab.
• OSTI ID: 6607317
• Report Number(s): AD-A-200019/8/XAB
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BARYONS
DIFFUSION
ELEMENTARY PARTICLES
FERMIONS
HADRONS
INTERPLANETARY SPACE
MAGNETIC FIELDS
NUCLEONS
PROTONS
RADIATIONS
SCATTERING
SHOCK WAVES
SOLAR ACTIVITY
SOLAR PARTICLES
SOLAR PROTONS
SOLAR RADIATION
SOLAR WIND
SPACE
STELLAR RADIATION