Construction and operation of a Mirror Langmuir Probe diagnostic for the Alcator C-Mod tokamak
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2008
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| Online Access: | http://hdl.handle.net/1721.1/40321 |
| _version_ | 1826210922782261248 |
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| author | Lyons, Laurence Anthony |
| author2 | Brian LaBombard and Ronald R. Parker. |
| author_facet | Brian LaBombard and Ronald R. Parker. Lyons, Laurence Anthony |
| author_sort | Lyons, Laurence Anthony |
| collection | MIT |
| description | Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007. |
| first_indexed | 2024-09-23T14:57:54Z |
| format | Thesis |
| id | mit-1721.1/40321 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T14:57:54Z |
| publishDate | 2008 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/403212019-04-10T17:47:51Z Construction and operation of a Mirror Langmuir Probe diagnostic for the Alcator C-Mod tokamak Lyons, Laurence Anthony Brian LaBombard and Ronald R. Parker. Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. Electrical Engineering and Computer Science. Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007. This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. Includes bibliographical references (p. 119-120). Langmuir probe diagnostic systems presently employed on Alcator C-Mod and elsewhere generally suffer from a severe limitation: unless multiple electrode or high-frequency bias techniques are employed, these systems can not resolve the rapid changes in plasma electron temperature, floating potential and ion saturation current that are associated with plasma turbulence. Moreover, no existing system can provide real-time output of these three parameters using a single electrode. To remedy this limitation, an advanced, high-bandwidth Langmuir probe system has been constructed for Alcator C-Mod using state-of-the-art design tools and components. The system produces a fast-switched, three-state probe bias waveform and employs a new method for outputting plasma conditions in real-time, a 'Mirror Langmuir Probe' (MLP), which utilizes high-bandwidth bipolar transistors to electrically simulate a Langmuir probe's response. Detailed information on the design, construction and performance of this new diagnostic is described in this thesis, representing the first proof-of-principle demonstration of the MLP technique. The MLP system was found to meet all the performance goals set forth at the beginning of the project: real-time output of electron temperature, floating potential and ion saturation current, ability to track changes in plasma parameters within a ~1 [mu]s timescale, while utilizing only a single Langmuir electrode. The system was tested using an 'electronic Langmuir probe' and also using an actual Langmuir probe in Alcator C-Mod. In both cases, the system accurately locked onto changing plasma conditions (< ~5% error in outputted parameters), with the exception of some severe transient events found in C-Mod plasmas (ELMs), which challenged the system's accuracy. (cont.) Further refinements to the system have been identified to handle such cases. The MLP clearly demonstrated superior performance to existing Langmuir probe systems on Alcator C-Mod and should enable researchers to study edge plasma turbulence in much greater detail in the future. by Laurence Anthony Lyons. S.M. 2008-02-27T20:38:24Z 2008-02-27T20:38:24Z 2007 2007 Thesis http://hdl.handle.net/1721.1/40321 191913315 eng M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 125 p. application/pdf Massachusetts Institute of Technology |
| spellingShingle | Electrical Engineering and Computer Science. Lyons, Laurence Anthony Construction and operation of a Mirror Langmuir Probe diagnostic for the Alcator C-Mod tokamak |
| title | Construction and operation of a Mirror Langmuir Probe diagnostic for the Alcator C-Mod tokamak |
| title_full | Construction and operation of a Mirror Langmuir Probe diagnostic for the Alcator C-Mod tokamak |
| title_fullStr | Construction and operation of a Mirror Langmuir Probe diagnostic for the Alcator C-Mod tokamak |
| title_full_unstemmed | Construction and operation of a Mirror Langmuir Probe diagnostic for the Alcator C-Mod tokamak |
| title_short | Construction and operation of a Mirror Langmuir Probe diagnostic for the Alcator C-Mod tokamak |
| title_sort | construction and operation of a mirror langmuir probe diagnostic for the alcator c mod tokamak |
| topic | Electrical Engineering and Computer Science. |
| url | http://hdl.handle.net/1721.1/40321 |
| work_keys_str_mv | AT lyonslaurenceanthony constructionandoperationofamirrorlangmuirprobediagnosticforthealcatorcmodtokamak |