Electron and Ion Temperature Measurements for the Terrestrial Reconnection Experiment

The Terrestrial Reconnection EXperiment (TREX) at the Wisconsin Plasma Physics Laboratory (WiPPL) studies collisionless magnetic reconnection. Since the plasma parameters change quickly in TREX as reconnection is occuring, there is not enough time to scan the probe bias as is usually done. Instead, in order to fit an I-V curve, a 16 tip Langmuir probe array and three magnetic flux coils is inserted into the experiment. Each probe tip is biased to a different potential between -120 and 120 V allowing us to characterize the full I-V curve. The tips are made of Mo to reduce sparking of the tips when biased at the extremum. The three flux coils combined with a separate linear array of coils allows us to more accurately identify the probes placement in the layer. As the experiment is run, the reconnection layer is jogged downwards which allows us to measure across the layer in each shot. By using the evolving I-V curve, we can find the electron and ion temperature and density by assuming the plasma is Maxwellian.