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)