A New Diagnostic Chamber For Fast Thruster Development

To support the further development of the cylindrical and coaxial HEMP thruster family, Thales assembles a new vacuum test chamber equipped with diagnostic tools to completely characterise the ion beam of a thruster. The measurement of the global parameters thrust, power to thrust ratio and specific impulse is performed by means of high resolution mechanical thrust balance, power and flow metering, respectively. The full information on the angular distribution, velocity distribution and charge state of the ions is obtained by means of an energy selective mass spectrometer mounted on the chamber wall. The polar beam angle variation is obtained by rotation of the thruster exit centre around a vertical axis. The new diagnostic chamber allows to identify the effects of modified permanent magnetic circuits or channel geometries within fast iteration cycles. The chamber volume of 2.4 m diameter x 4.0 m length and an effective Xenon pumping speed up to 100.000 l/s, mainly by means of cryo pumps, guarantees minimal impacts of the test environment on the thruster performance. A special geometrical arrangement of the chamber wall shields minimises the deposition of sputtered chamber wall material on the thruster channel ceramics and thus eases the free space life prediction of a thruster. This paper gives an overview of the current status of the facility and the planned activities.