@article{discovery162799, note = {Copyright 2005 by the American Geophysical Union}, volume = {32}, month = {December}, number = {24}, journal = {Geophysical Research Letters}, year = {2005}, title = {Ion sound wave packets at the quasiperpendicular shock front}, publisher = {American Geophysical Union}, url = {http://dx.doi.org/10.1029/2005GL024660}, issn = {0094-8276}, abstract = {Electric field measurements from a single spacecraft have been used to study ion-sound turbulence observed within the Earth's bow shock. The observed frequency of the ion-sound waves can be both lower and higher than the local electron cyclotron frequency depending upon the direction of wave propagation in the plasma rest frame. The ion-sound waves observed upstream of the ramp can not be generated either by an instability related to the gradient in the electron temperature or an electric current within the ramp. A comparison of wave vectors for distinctive wave packets indicate that non-stationary, short scale current layers formed in the processes of the ramp evolution might be the source of the free energy for such waves.}, author = {Balikhin, M and Walker, S and Treumann, R and Alleyne, H and Krasnoselskikh, V and Gedalin, M and Andre, M and Dunlop, M and Fazakerley, A} }