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| INSTITUTET FÖR RYMDFYSIK | UPPSALA |
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| Swedish Institute of Space Physics | (59°50.272′N, 17°38.786′E) |
Master Project (30 c)/Masterprojekt (30 hp)
Swarm LP bias sweeps
Student: David Rodriguez Otero, Royal Institute of Technology (KTH)Supervision team: Anders Eriksson, Stephan Buchert, Thomas Nilsson, Fredrik Johansson
Period: Spring 2021
Description
A Langmuir probe (LP) is essentially an electrode exposed to a plasma, with attached electronics whose core parts are a voltage source and an electrometer. The voltage source applies a bias voltage to the probe and the resulting probe current is measured. If the probe potential is positive (negative), electrons are attracted (repelled) and positive ions repelled (attracted). For simple shapes (e.g. spheres and cylinders) theoretical expressions for the probe current as function of voltage and plasma properties can be derived, and fits of the measured data to such expressions are routinely used to derive properties like electron density and temperature. ESA's three Swarm satellites are since November 2013 in low Earth orbit with primary aim to investigate the geomagnetic field. All the satellites carry a LP instrument from the Swedish Institute of Space Physics (IRF) in Uppsala. The LP instrument on each satellite has two spherical LPs. In this project, a representative sample of all the sweeps we have acquired during the mission will be investigated for better characterization of surface contamination and other non-ideal effects on the data.Results
Project report
![[Swarm]](../../img/swarm.jpg)
Swarm in space. The LPs on the nearest satellite can be seen as small sticks protruding downward from the lower front edge of the spacecraft. [Credit: ESA/P.Carril]