Vibration Test of a Breadboard Gimbal for the NEXT Ion Engine

Abstract

*† † ‡ § ** The NEXT propulsion system is an advanced ion propulsion system presently under development that is oriented towards robotic exploration of the solar system using solar electric power. The subsystem includes an ion engine, power processing unit, feed system components, and thruster gimbal. The breadboard gimbal that has been developed is a lightweight, two-axis design using a four-bar linkage mechanism that provides a positive captured configuration for launch while providing for up to twenty degrees of thrust angle articulation while in the operational configurat ion. In this paper, the results of dynamic environmental testing of the gimbal with a thruster mass model are presented. The gimbal/mass-model assembly was subjected to qualification-level random vibration loads and survived with no significant issues. Acceleration and force data were acquired at the interface between the gimbal and the thruster to facilitate structural modeling of the thruster in response to the loads transmitted through by the gimbal. Shock spectra at levels significantly less than the project requirements were applied to the gimbal/mass-model assembly using two different methods in order to characterize the transmission of shock loads from the base of the gimbal to the thruster location. Hammer blow impacts were more representative than vibration table shock approximations of actual pyrotechnic devices and the expected shock attenuation through the gimbal. Post-test analysis showed that the gimbal structure stresses are comfortably within design margins.