Millimeter-Wave Diagnostics for EAST. Calvin Domier , Xiangyu Kong , Liubing Yu , Alexander Spear , Shao Che, N.C. Luhmann, Jr. University of California at Davis (UC Davis) - PowerPoint PPT Presentation
Millimeter-Wave Diagnostics for EAST Calvin Domier, Xiangyu Kong, Liubing Yu, Alexander Spear, Shao Che, N.C. Luhmann, Jr. University of California at Davis (UC Davis) Chen Luo, Jinlin Xie, Bingxi Gao, Yilun Zhu, Wandong Liu, Changxuan Yu University of Science and Technology of China (USTC) Liu Yong, Liqun Hu, Han Xiang Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) 2012 US-PRC Magnetic Fusion Workshop July 10-12, 2012 – La Jolla, CA UC DAVIS PLASMA DIAGNOSTICS GROUP
Transcript
Millimeter-Wave Diagnostics for EAST
Calvin Domier, Xiangyu Kong, Liubing Yu, Alexander Spear, Shao Che, N.C. Luhmann, Jr.
University of California at Davis (UC Davis)Chen Luo, Jinlin Xie, Bingxi Gao, Yilun Zhu, Wandong Liu,
Changxuan YuUniversity of Science and Technology of China (USTC)
Liu Yong, Liqun Hu, Han XiangInstitute of Plasma Physics, Chinese Academy of Sciences (ASIPP)
2012 US-PRC Magnetic Fusion WorkshopJuly 10-12, 2012 – La Jolla, CA
radiation spanning a frequency range of 104 to 168 GHz● Collaborative effort with the Institute of Plasma Physics,
Chinese Academy of Sciences (ASIPP) in Hefei, China
ECE Imaging (ECEI) ● High resolution 2-D ECEI system generates 24x16 images of
Te profiles and fluctuations in the EAST plasma● System spans an RF bandwidth of 14.4 GHz, and is tunable
over a frequency range of 102 to 150 GHz● Collaborative effort with the University of Science and
Technology of China (USTC) in Hefei, China
Electron Cyclotron Emission (ECE) ● Electron gyromotion results in Electron Cyclotron
Emission (ECE) at a series of discrete harmonic frequencies: ωn =nωce
● In an optically thick plasma, the ECE radiation intensity is the black body intensity (Rayleigh-Jeans Region):
● In tokamak plasmas, there is a one to onemapping between frequency and radial positiondue to 1/R dependence of magnetic field B.
ωce µ B µ1/R
● ECE has become a standard technique tomeasure Te profiles and fluctuations inmagnetic fusion plasmas
B
R
ECEfce
2( ) ( )B eI I T µ
ECE Heterodyne Radiometer System
●Schematic illustration of the EAST radiometer receiver●Plasma radiation enters from the left
BS1 BS2 BS3
104-168 GHz
104-
120
GH
z
120-
136
GH
z
136-
152
GH
z
51 GHz
To Band 1
59 GHz
To Band 2
67 GHz
To Band 3
75 GHz
152-168 GHz
To B
and
4
Dichroic Plate
HDPE Lens
Subharmonic Mixer
ECE Heterodyne Radiometer System
●Photograph of the EAST radiometer receiver.●Plasma radiation enters from the right
Sub-harmonic Receiver● Each receiver consist of a sub-
harmonic mixer pumped by a solid state Gunn oscillator
● ECE radiation is downconverted, amplified by a 2-18 GHz low noise preamplifier placed within the shielded enclosure
● Three translation stages provide full alignment capability, with a vertical stage mounted within and a horizontal stage mounted below the enclosure box, and an axial (focusing) stage mounted underneath a focusing lens placed in front of the receiver
ECE Radiometer Optical DesignReceiver
1Receiver
2Receiver
3Receiver
4Frequency Range (GHz) 104-120 120-136 136-152 152-168
Simulation Wavelength (mm) 2.88 2.50 2.20 1.98Distance from window to
● The output of each receiver is amplified further using a second low noise 2-18 GHz pre-amplifier, and is divided into two parts
● One half is lowpass filtered and feeds the four lower frequency channels, while the other half feeds the four higher frequency channels
● A four-wave power divider splits each of these signals again, with the resultant 8 channels all passing through individual bandpass filters(~500 MHz wide) before getting rectified by coaxial detectors and connecting to an 8-channel video amplifier/filter board
allow an extension of well-established principles of heterodyne radiometry.
● Real-time Te down to <1%or µ-sec time resolution
● Up to 1 cm2 spatial resolution● 2-D localized measurements
using wideband IF electronics and single sideband detection.
fce
R
fce
R
Double Downconversion Approach (1)
A characteristic frequency plot forthe EAST tokamak (BT=2.1 T) is shown left, showing X-mode ECE spanning 94 GHz to >160 GHz
MixersDetectors
Antennas
Mixers
LP FiltersLO
LOnNotch Filter
ADCs
PlasmaOptics
Dichroic Plate
LO1
90
100
110
120
130
140
150
160
140 160 180 200 220
Freq
uenc
y (G
Hz)
Major Radius (cm)
3fC
2fC
fECRH
Quasi-optical notch filter prevents transmission of a narrow band of frequencies to protect against stray 140 GHz ECRH
90
100
110
120
130
140
150
160
140 160 180 200 220
Freq
uenc
y (G
Hz)
Major Radius (cm)
3fC
2fC
fECRH
MixersDetectors
Antennas
Mixers
LP FiltersLO
LOnNotch Filter
ADCs
PlasmaOptics
Dichroic Plate
LO1
Double Downconversion Approach (2)
Dichroic plate ensures single sideband operation: effect offcutoff = 110 GHz plate shown left
90
100
110
120
130
140
150
160
140 160 180 200 220
Freq
uenc
y (G
Hz)
Major Radius (cm)
3fC
2fC
fECRH
MixersDetectors
Antennas
Mixers
LP FiltersLO
LOnNotch Filter
ADCs
PlasmaOptics
Dichroic Plate
LO1
Double Downconversion Approach (3)
Antennas receive broadband ECE, downconvert by fLO
(at or near fcutoff), and amplified: example shows fLO=110 GHz combined with 2-20 GHz amplifiers
90
100
110
120
130
140
150
160
140 160 180 200 220
Freq
uenc
y (G
Hz)
Major Radius (cm)
3fC
2fC
fECRH
MixersDetectors
Antennas
Mixers
LP FiltersLO
LOnNotch Filter
ADCs
PlasmaOptics
Dichroic Plate
LO1
Double Downconversion Approach (4)
Downconverted 2-20 GHz signals are split into n bands and downconverted a second time by frequencies fLO1 through fLOn in the 2-9.2 GHz range: shown left are two such channels
90
100
110
120
130
140
150
160
140 160 180 200 220
Freq
uenc
y (G
Hz)
Major Radius (cm)
3fC
2fC
fECRH
f (GHz)2.5 8.8
MixersDetectors
Antennas
Mixers
LP FiltersLO
LOnNotch Filter
ADCs
PlasmaOptics
Dichroic Plate
LO1
Double Downconversion Approach (5)
Final step is to lowpass filter the n band signals, reducing the radial spot size and providing sharp band edges suitable for cross correlation studies
90
100
110
120
130
140
150
160
140 160 180 200 220
Freq
uenc
y (G
Hz)
Major Radius (cm)
3fC
2fC
fECRH
f (GHz)2.5 8.8
MixersDetectors
Antennas
Mixers
LP FiltersLO
LOnNotch Filter
ADCs
PlasmaOptics
Dichroic Plate
LO1
Double Downconversion Approach (6)
ECEI Imaging Array
Conventional ECEI: 8-Channel RF Layout
7.9/7.0 GHz
8.8/7.6 GHz
2.5/3.32 GHz
3.4/4.0 GHz
4.3/4.6 GHz
5.2 GHz
6.1/5.8 GHz
7.0/6.4 GHz
0-31.5 dB
6-bitAttenuator
Filters
Power Dividers
Mixers
New for EAST: 16-Channel RF Layout9.7 GHz
10.6 GHz
11.5 GHz
12.4 GHz
13.3 GHz
15.1 GHz
x2 8.0 GHz
0-31.5 dB
20 dB
6-bitAttenuator
14.2 GHz
20 dB
20 dB
HPF
HPF
MixersDoubler
To Lower8 channels
2- 16.4 GHz Input
ECEI Optical Design
● Zoom optics can control the vertical spacing between antenna elements over a factor of 2X, from 11.5-13.8 mm to as high as 21.5-24.5 mm
● Focuser lens determines the beam waist position within the plasma,can be set to -26.7cm ≤ r ≤ +55.2cm in the narrowest zoom configuration
ECEI Array
Plasma Edge
Vacuum Window
Toroidal Corrective Lens
Zoom Optics
Focuser
Toroidal Colliminating Lens
Beam Waist
Lexan Optical Enclosure Boxes
● In narrow zoom, the Gaussian beams are focused at the plasma edge (left), and at its deepest location (right).
●Focused on the magnetic axis, the image plane is adjusted from narrow zoom (left) to wide zoom (right).
ECEI Gaussian Beam Simulations22:07:09
Narrow,Edge Scale: 0.04 29-Sep-10
694.44 MM
22:09:14
Narrow,Deepest Scale: 0.03 29-Sep-10
757.58 MM
22:27:47
Narrow,Magnetic Axis Scale: 0.03 29-Sep-10
735.29 MM
22:28:25
Wide,Magnetic Axis Scale: 0.04 29-Sep-10
714.29 MM
Narrow, Edge Narrow, Deepest
Narrow, Magnetic Axis Wide, Magnetic Axis
● The full diffractive characteristics of beam energy passing through system apertures is revealed through the use of numerical techniques employing Beam Propagation Method (BPM).
● Plotted here are the focal plane patterns at the magnetic axis in the narrow zoom position for the edge (left) and center (right) channels.
ECEI Beam Energy Simulations
700.36 mm
700.36 mm
-50.00
0.0000
-25.00
Narrow,Magnetic AxisBeam Intensity at Magnetic Axis
Relative Field ( 0.000, 0.000 ) POSITION 1Wavelength 2639752.00 nm.
1057.9 mm
1057.9 mm
-50.00
0.0000
-25.00
Narrow,Magnetic AxisBeam Intensity at Magnetic Axis
Relative Field ( 0.000, 0.000 ) POSITION 1Wavelength 2639752.00 nm.
ECEI Focal Plane Measurements
● Focal plane scans using a translatable scattering rod (functions as a line source) confirm good imaging performance
● Shown above are the E-plane (vertical) focal plane patterns of the centermost 8 channels, with fitted gaussians (─) superimposed over raw data (─)
ECEI Installed on EAST
ECEI ElectronicsCabinet
ECEI Optics
BWO
ECEI Installed on EAST
ECEI Electronics on EAST● ECEI electronics consist of
power supply/controllers and ECEI modules (8 per rack)
● ECEI electronics and high speed digitizers placed in shielded rack
● All 384 ECEI signals can be simultaneously sampled at2 MHz for 6 sec
