Impulsively Reflected Ions: A Plausible Mechanism for Ion Acoustic Wave Growth in Collisionless Shocks - Goodrich, KA; Ergun, R; Schwartz, SJ; Wilson, LB; Johlander, A; Newman, D; Wilder, FD; Holmes, J; Burch, J; Torbert, R; Khotyaintsev, Y; Lindqvist, P-A; et al. (JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2019)