Date of Award
Honors Thesis (Open Access)
Colby College. Physics and Astronomy Dept.
Duncan A. Tate
The project was started with an objective to investigate the eﬀect of radio fre- quency absorption in Ultra Cold Neutral Plasmas (UNPs). The plasma oscillation is density dependent and can be excited by using external radio frequency ﬁeld. A homodyne circuit is used to detect direct absorption of the radio frequency waves. The radio frequency waves are applied to conducting meshes which lie on either side of the plasma. The meshes are eﬀectively a capacitor, which together with inherent circuit resistance constitute a high pass ﬁlter. A small part of the gain and phase shift of the ﬁlter depend on the presence of the plasma. The gain change and phase change of the initial radio frequency signal by the high pass ﬁlter is observed using a digital oscilloscope. The gain change and the phase change signal can be used to identify the resonance point in the ultra cold neutral plasma. The resonant frequency is related to plasma expansion velocity, plasma temperature and plasma density. Therefore, by identifying resonant frequency various plasma parameters can be determined. The results of the experiment were used to identify various modes of plasma oscillations. Due to the limitation of time, only qualitative data analysis was performed. The results are in good qualitative agreement with the theory as well as previous exper- iments. The data obtained from this project as well as the understanding acquired here can be used in future experiments. In the future, a comprehensive quantita- tive analysis of the results is necessary to verify the underlying theories as well as accurately determine various plasma parameters.
Recommended CitationPoudel, Nirakar, "Electronic Detection of Ultra Cold Neutral Plasma" (2012). Honors Theses. Paper 639.
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