Interplanetary acceleration of low-energy protons as observed during the 25 september 1978 shock event

ISEE-3 observations of a long-lasting low-energy proton intensity increase during the 25 September 1978 shock event are presented as an example for interplanetary particle acceleration in association with shock waves. The observations are discussed in the light of current models for particle acceleration. The particular shape of the time intensity behaviour of the particle intensity increase, the existence of a shock spike and the observed particle distributions indicate that the particles are accelerated at the shock by the induced electric field $\text{E}\text{= ?}\text{1}\text{c}\text{V}\text{×}\text{B}$.