Poster Presentation
Interpretation of Double Langmuir Probe I-V Characteristics at Different Ionospheric Plasma Temperatures
Presenter: Shankar Bhattarai (Tribhuvan University)
A Single Langmuir probe is always connected to an electrode as fixed potential. In cases where such an electrode does not exist or the plasma potential is fluctuating significantly, this method is not relevant. This weakness was overcome by the development of the floating double probe by Johnson and Malter [1]. A distortion of the probe characteristics due to varying potential is eliminated, while the whole probe system is floating. This supports probe operation also in discharges with strongly varying potential.
Double Langmuir probes provide valuable information on the behavior of space plasmas including ionospheres and the interstellar medium. This research paper focuses on the study of Spherical Double Langmuir Probe I-V characteristics in Maxwellian interstellar plasma. To generate the exact plasma conditions of the experimental testing environments computational procedures is adopted. The investigations address the development of a technique to model Maxwellian plasma. Three different ionospharic plasma temperatures are theoretically taken and its effects on floating potential are studied in this research. The variation of floating potential and ion saturation current due to temperature is clearly depicted. A manifest trail in the I-V curves is the bump that occurs right after the floating potential. This feature in the transition region affects ability to determine the electron temperature, ion saturation current and plasma potential. Symmetric characteristic when both tips are of equal geometry is an important advantage of the double probe. Generally, all surfaces adjacent to plasma become contaminated with deposits, so also does any probe. Here I have also deliver some sense of how one might proceed to use these results in the analysis of experimental I-V curves obtained in space.
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