PROBA 2 - TPMU

BRIEF DESCRIPTION

The project is continuation of the PRODEX program and its aim is to develop and build the Thermal Plasma Measurement Unit - TPMU. The instrument comprises a Sensor Block (TPMU-S), which consist of probes and preamplifiers, and a Processing Block (TPMU-P). It should work onboard the PROBA-2 satellite but it can be used onboard other microsatellites too. Scientific aim of the instrument observation is to study parameters of thermal plasma which are crucial for the electromagnetic waves propagation in the upper ionosphere.

 

Principal Investigator   :  František Hruška

 

 

 

MORE DETAILS AND A WORKING PLAN

The Thermal Plasma Measurement Unit (TPMU) is proposed for the PROBA II mission as well as for future scientific satellite projects. It uses radio-frequency (RF) probe for the electron temperature and floating potential measurement, and retarding potential analyzer (RPA) for the ion temperature and total ion density measurement. Proven measurement methods are joined with the new electronic design to provide more accurate and reliable but still low cost instrument.

The instrument comprises a Sensor Block (TPMU-S), which consist of probes and preamplifiers, and a Processing Block (TPMU-P). Probes developed in the Institute of Space Research, Moscow, Russia are used.  The field of view of the probes, configured either in a linear array or in a pyramid, should be oriented in direction of velocity vector. The Sensor Block can be located either on the satellite surface or on the boom and is connected by a cable with the Processing Block located behind it or inside the satellite body. The construction of the Sensor Block can be modified according to the satellite mechanical layout, to the planned orbit and satellite orientation. The aim of the further development is to encase all the electronics to the Sensor Block.

The electron temperature part uses three simple circular planar probes with guarding rings. A constant voltage shift ∆U is kept by applying the proper amplitude of RF signal. The probe potential is periodically searched and adjusted for minimal value of electron temperature.

The ion part uses a three-grid planar trap. The ion measurement can work in two modes: (i) measurement of ion flux at plasma potential, (ii) the measurement of volt-ampere retarding characteristics. The analysing voltage varies in 256 steps from 0 to 12V. This voltage is given by the sum of floating potential, voltage difference between plasma and floating potential (calculated from Te probe) and auxiliary voltage.

Measured parameters:

• Total ion density - (2.107 – 8.1012-3) m
• Ion temperature - (800 -10000K)
• Electron temperature - (800 - 20000K)
• Floating potential - (+/- 12V)

 
The project is proposed for two and half years starting on July 2003 (month 0) and broken down to following workpackages:

 

WP1 : final proposal of mechanical and electrical construction, lasting the first 6 months

WP2 : development and construction of the engineering model, up to month 12

WP3 : manufacturing and testing of the flight model and pre launch preparation, up to month 24

WP4 : software evaluation, first data collection, interpretation and publication, up to month 30