Speaker
Description
This is an ongoing ESA PRODEX project, the overall objective of this project is a proof-of-concept that a VLF transmitter, with a magnetic loop/solenoid antenna on a LEO satellite, is capable of transmitting wave power in the Very-Low-Frequency and at an amplitude range comparable to the typically observed peak power of the naturally occurring whistler-mode waves (whistler, chorus, hiss) in the magnetosphere.
Results of recent experiments (DSX) concluded, that VLF transmitters using large electric dipole antenna may not be suitable to transmit wave energy comparable for natural signals generated in or propagating through the inner magnetosphere.
The POPRAD (Probing the Plasmasphere and the Radiation Belts) concept uses magnetic antenna to generate VLF impulses for four purposes:
• monitoring the electron density of the plasmasphere
• triggering wave particle interaction in the RB to monitor the seed and source population
• monitoring the ionosphere by ‘VLF-TEC’
• monitoring the termosphere neutral density variation by VLF amplitude attenuation
The critical point is the efficacy of the transmitter. The emitted wave power needs to be in the same rage as the those of the natural waves in the inner magnetosphere. The efficacy will be tested in a plasma chamber at ESTEC. The plasma chamber is currently at a pre-study stage. The plasma column in the chamber is planned to be a straight cylinder, the plasma dimension is ∅ 0.5m x 4m, the electron density is between 108-12/cm3 and it is planned to be embedded into a homogeneous static magnetic field of 0.2-3 kG.
These plasma parameters allow to test the efficacy of the transmitter using the similarity principle transforming the VLF range (1-10kHz) to 1-10MHz range, that allows to measure the wave power in the far field within the plasma chamber.
The plasma chamber will be able to maintain the plasma for long term, thus it can be used not only for testing instruments/sensors in plasma, but for performing environment tests of various sensors, electronic parts, materials exposing them to plasma conditions. No such capability is available in ESA member states at the moment, thus the planned plasma chamber will highly improve the environmental testing capabilities of ESA.
