In Flight Research on Real Gas Effects Using the ESA EXPERT Vehicles

Compact Electron Gun Based on Secondary Emission Through Ionic Bombardment

“…The overall power consumption is less than 130 W : 60 W for the cathode power supply, 30 W for the ion source, 24 W for the turbopump, 1.2 W for the focusing coil (12 V–100 mA), nearly 2 W for the beam pulsation system and a few Watts for the optical detectors (CCD camera and spectrometer) and control electronics. These features are compatible with the requirements for in-flight experiments onboard a vehicle such as described in Reference 12 or onboard a rocket for characterizing locally the atmosphere at high altitudes between 50 and 100 km [ 16 ]. Detailed results of the experimental validation of this set up in a wind tunnel will be published soon.…”

“…In this most common gun, a heated cathode, built from massive tungsten or barium compound, emits low energy electrons which are then accelerated and focused on a target. This kind of electron gun has however several drawbacks for our intended in-flight application aiming at performing EBF measurements in the flow around an atmospheric reentry vehicle [ 12 ]. First, the heated cathode, the control electrode and the accelerating electrode must all be under secondary vacuum at a pressure lower than 10 −3 Pa. Second, the power necessary for heating the cathode must be at least 20 W to produce an electron current of 1 mA and the power supply must be floated at the level of the accelerating voltage with the use of an isolation transformer.…”