Particle acceleration at a rippling termination shock

Shortly after the prediction of the solar wind, the existence of the termination shock (TS) was proposed. Bounding the supersonic wind, the TS has long been thought as the acceleration site for anomalous cosmic rays (ACRs). On December 16th, 2004, Voyager I crossed the TS and entered the inner heliosheath; verifying earlier predictions of the existence of the TS. However, in sharp contrast with earlier theoretical predictions, data from Voyager I did not show an unfolded spectrum at the TS. Instead, the spectrum kept unfolding after crossing the shock. One possible explanation for the missing ACRs was suggested by McComas and Schwadron (2006), who argued that the deficiency in ACRs observed by Voyager I can be attributed to the geometry of a blunt TS. We show in this paper, with a careful consideration of the transport time scale in the inner heliosheath, that a large-scale rippling TS is necessary to apply the idea of McComas and Schwadron (2006).