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Christina De Bianchi Howard University Advisors: Ellen Zweibel & Jay Anderson Summer REU 2009 University of Wisconsin-Madison Madison, WI.

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Presentation on theme: "Christina De Bianchi Howard University Advisors: Ellen Zweibel & Jay Anderson Summer REU 2009 University of Wisconsin-Madison Madison, WI."— Presentation transcript:

1 Christina De Bianchi Howard University Advisors: Ellen Zweibel & Jay Anderson Summer REU 2009 University of Wisconsin-Madison Madison, WI

2  Brief background on the MST.  What is a plasma?  What are EBW’s?  How can EBW’s assist the MST?  Motivation  Set Up  Results.  Conclusions.  Future Work.  Astronomy Community.

3  A reversed field pinch physics experiment.  Fusion energy research and astrophysical plasma research.  The device was built to produce and contain near thermonuclear plasmas.

4 A hot ionized gas that requires a large number of particles. Plasmas are confined by magnetic fields. Quiescent plasma made at LAP.

5  The Electron Bernstein Wave is an electrostatic wave that propagates perpendicular to B 0.  The variation of density creates the electric field of the wave. The gyro motion of the electrons carries the wave. K (propagation vector) E

6  The EBW is a method of injecting energy into a plasma to increase its temperature to reach fusion conditions.  Being able to heat the plasma will help us create a cost effective efficient fusion reactor.

7  The diagnostic will discern plasma properties during EBW launch;  Measure the phase difference between the forward and reflected waves;  Also used for diagnosis of plasma (i.e. temperature).

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9 IF Transformers Splitter Mixers

10  The forward and reflected sine waves are multiplied with a wave of GHz with mixers. Beat FREQUENCY: 455 KHz: dashed 11 GHz: purple Red= GHz Blue= 5.5 GHz

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12 In waveguide Vacuum λ wg, e = 8.46 cm λ wg, t = 7.68 cm. Experimental error = 10.15% 5.5 GHz λ vacuum = c/f λ c = 2πr/1.841 λ wg = λ vacuum /√1-(λ vacuum /λ c ) ⌃ 2

13 Motivation: Measure the wavelength in quartz. (We are using the quartz as a microwave window as well). We want the window to be ½ a wavelength thick for destructive interference and maximizing transmission.

14 Experimental Results: λ vacuum =7.003 cm λ quartz = 3.35 cm λ quartz /2 = cm Theoretical Results: λ vacuum = cm λ quartz = none Index of Refraction: n= λ vacuum /λ quartz n = 2.10 for quartz at 5.55 GHz λ=360°/slope

15  A heterodyne circuit has been constructed to measure phase differences between waves at 5.5 GHz.  This diagnostic, to date, has been used to characterize an EBW launching antenna and to help find specifications for a microwave vacuum window.

16  The circuit will be an integral part of EBW heating system in the MST.  This is necessary for temperature diagnosis of the plasma in the torus.  Additionally, it will help measure edge electron density.  The phase between launched and reflected waves indicates the position in the plasma where mode conversion (energy in one wave is converted to another wave) to the EBW occurs.

17  The study of laboratory plasmas can led insight to astrophysical topics such as solar winds, accretion disks, and dynamos.  Magnetic fields in the MST configure itself in a fashion possibly similar to the manner in which it occurs in the solar corona.


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