progress and new results from the h-1nf scanning interferometer scott collis, george warr, john...
Post on 21-Dec-2015
217 views
TRANSCRIPT
![Page 1: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/1.jpg)
Progress and New Results from the H-1NF Scanning
InterferometerScott Collis, George Warr,
John Howard
![Page 2: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/2.jpg)
A Time Multiplexed Interferometer
• The System is basically described as two Michelson Interferometers with a time varying viewing path viewing
• The phase shift induced by the plasma is given by
• The signal is time multiplexed, which means we only need one detector per probe beam
dlnλr2Δφ ec
![Page 3: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/3.jpg)
![Page 4: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/4.jpg)
Beams are swept by a grating wheel
• Wheel speed can be varied from 0-6000rpm
• At 6000 rpm with a 6 partitioned wheel one scan of the plasma takes 1.8ms
• The wheel also Doppler shifts the beam:
dmRf /
![Page 5: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/5.jpg)
Motor and Grating
![Page 6: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/6.jpg)
Continuous Grating allows viewing of small structures
• The grating constant changes linearly across a sector
• Possibility of seeing small structures, of order 1cm (beam size) such as islands and transport barriers
• Data can aliased when frequency of plasma oscillations approaches the scan frequency of the interferometer
![Page 7: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/7.jpg)
Fosc > Fscan
![Page 8: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/8.jpg)
Aliased Data
![Page 9: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/9.jpg)
Calibration
•We need a transform from temporal position in scan
to spatial position in the H-1NF tank
![Page 10: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/10.jpg)
A 2.5cm absorber was placed at three positions on the bottom
mirror
![Page 11: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/11.jpg)
At 40cm above the centre
![Page 12: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/12.jpg)
In the centre of the mirror
![Page 13: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/13.jpg)
And at 40cm below the centre
![Page 14: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/14.jpg)
Top Diagonal Results
Beam width: 1.3cm
![Page 15: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/15.jpg)
Bottom Diagonal Results
Beam width: 3.2cm
![Page 16: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/16.jpg)
Calculated Beam Positions
![Page 17: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/17.jpg)
High Density ICRH Shot
•Fundamental ICRH resonance of Hydrogen
•B=0.5T
•Peaked density profile
•Highest B2ne product observed in H-1NF
![Page 18: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/18.jpg)
Possibilities
• With the wheel running at high speed it is possible to get temporally and spatially resolved information on the plasma decay
• From this it will be possible to solve the two dimensional diffusion equation
• With the new ICRH mode it is possible to study the physics of fully ionized plasmas in H-1NF
![Page 19: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/19.jpg)
But first….
• To tomographically reconstruct density maps of the H-1NF plasma we need a greater coverage of the plasma
• We will be expanding the fan of the diagonal views and installing a central view
![Page 20: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/20.jpg)
Using the interferometer to understand particle transport
• Using a gas puffer it is possible to modulate the source term in the continuity equation
• By modulating the gas flow and using the high temporal and spatial resolution of the interferometer it is possible to gain an insight into how particle transport occurs in H-1NF
• Information can be combined with other instruments to gain not only ne but Te Ti and ion velocity
![Page 21: Progress and New Results from the H-1NF Scanning Interferometer Scott Collis, George Warr, John Howard](https://reader031.vdocuments.mx/reader031/viewer/2022032201/56649d545503460f94a31af6/html5/thumbnails/21.jpg)
Conclusion
• The H-1NF Scanning interferometer can make spatially and temporally resolved measurements of the plasma with resolutions of up to 1cm and 1.8ms
• As the system is upgraded the data it produces will provide physical insight into the behavior of flexible Heliac plasmas