New Development of the Plasma Diagnostics

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New Development of the Plasma Diagnostics on
HL-2A Present by Zhou Yan Southwestern
Institute of Physics, Chengdu, Sichuan, 610041,
China
The 3rd PRC-US Magnetic Fusion Collaboration
Workshop
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Introduction

• HL-2A is a middle size ( R1.45m, a 0.40m)
  tokamak with a closed divertor. The main subjects
  are investigation of the divertor and edge plasma
  physics, plasma transport and its mechanism,
  plasma profile control with auxiliary heating and
  so on. A great number of diagnostics have been
  designed and equipped on the device. Among them
  some new diagnostics have been developed
• 8-channel laser interferometer with 6 meter HCN
  laser for electron density profile measurement
  with good spatial resolution.
• Two wave bands microwave reflectometry for
  investigation of the density behavior and
  particle transport.
• A new step electrostatic probe array for Zonal
  Flow studying.
• Two channels SDD detector to measurement the Te

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Diagnostics Layout on the HL-2A Tokamak
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The plasma diagnostic systems on the HL-2A tokamak

• Electron density profile measurement
• 8 Channel HCN laser Interferometer
• (1x10123.5x1014cm-3)
• for Core Plasma Confinement region
• Microwave Reflectometry, 26-60GHz (0.8 -
  4.5x1013cm-3)
• for Confinement region
• Moveable and fixed probes array
• for Edge of Plasma
• 4 Channel Microwave Interferometers
• (with 4mm and 8mm wave length)
• For Up and Down Divertor

• Electron Temperature profile Measurement
• Laser Thomson Scattering,8 time points,5 spatial
  points
• (for electron absolute measurement)
• 2mm Microwave Scanning receiver,20 spatial
  point,time resolution 4ms
• (for electron temperature profile)
• 16 Channel ECE receiver with high time
  resolution(for fast phenomena)
• Electrostatic Probes
• ( for electron temperature of edge and divertor
  plasma)
• 2 (9) Channel Soft X Ray Spectrometer
• ( for electron absolute measurement )

• Multi-Channel Detector arrays
• Soft X-Ray System 5 arrays 100 Channels
• Bolometer system 3 4 arrays 48 Channels
  
• Ha measurement 2 arrays 92 Channels

Ion Temperature Measurement Charge Exchange
Neutral Particle Analyzer The Main Parameters
Energy Channel 8 Time resolution 1 ms Ion
temperature range 0.22keV
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The plasma diagnostic systems on the HL-2A tokamak

• VUV and Visible Spectrometer
• A one-channel VUV spectrometer was used to
  monitor the impurities on HL-2A. (10-200 nm)
• 4 channel visible OMA system with 3 grating (
  150g/nm,1800g/nm,2400g/nm) has been used on
  HL-2A.
• spectrum range 380-1100nm
• integrating time 80ms
• resolution 0.01 nm
• Some optic fibers are located at different
  positions of main and divertor chamber to observe
  the Ha emission and impurity radiations.
• A multi-channel VUV spectrometer to investigate
  the impurity behaviors.

• Diagnostics for the edge divertor plasma
• Infrared camera
• Bolometer array
• Ion species by mass spectrum (Omegatron)
• Neutral gas pressure measurement (fast ionization
  gauge)
• Probe arrays -- include fixed (at target plate),
  movable and Pneumatic probe array
• Microwave interferometer at divertor chamber
• Optics spectrum (such as Ha)

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Soft X ray signals of the different arrays
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The flush Langmuir probe array fixed on divertor
neutralization target plate

• Spatial resolution
• Z-direction1cm
• Toroidal direction1.5cm
• Time resolution
• 0.001ms

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Identification of the Divertor Configuration on
HL-2A
Radiation power profiles along different chords
at 4 times for shot 1906
Temporal evolution of electron temperatures on
outer target for shot 1906
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8 Channel HCN laser Interferometer

• wavelength 337µm
• channel number 8
• velocity of rotation grating
  2001500/min
• laser power 400mW(design)
• laser length 6 m

A new HCN laser, with designed power of 400mW,
and interferometer with 8-channels are being
designed and installed on HL-2A.
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6 meters HCN laser on the HL-2A tokamak
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6 meters HCN laser on the HL-2A tokamak
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Time delay Scanning Microwave Reflectomatry

• Frequency range26-60GHz
• Electron density measurement range 0.8 -
  4.5x1019m-3
• Time resolution 1ms
• Special resolution 0.5cm

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Electron density profile measurement
Comparison between the electron density profile
and the electron temperature profile by ECE
Phase-Q
Phase-I
Amplitude
Scanning voltage
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The electrostatic probes for Zonal Flow
Zonal flows are very interesting topics for the
anomalous transport3.4. The active studies in
the area are aimed at understanding physics
mechanism and finding way to control it. A new
electrostatic probe system has been designed and
used to investigate the zonal flows on HL-2A. The
main feature of the probes is three step
structure, as shown in Fig 4. Three arrays of the
probes are distributed 6.5cm and 80cm apart
poloidally and toroidally. To study the poloidal
and toroidal correlation of the turbulence, it is
very important to put the probes at the same
magnetic surface. It seems very difficult to
realize by the single probes, but using the three
steps electrostatic probes, the problem can be
solved, because there is always a probe in the
same magnetic surface with one of the three
probes in the other probe array. 3Z.Lin,
et.al. Science 281,1835 (1998) 4
P.H.Diamond,et.al, Plasma Phys. Control. Fusion
47.R35 (2005)
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The electrostatic probes for Zonal Flow
Three dimensional features of geodesic acoustic
mode zonal flow are measured with the probes at
the edge of the HL-2A tokamak plasma for first
time. The symmetries (m0 1, n 0) of the low
frequency ( f 7-9kHz) electric potential and
field are simultaneously observed.
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Density and temperature profile measured by
fast-scanning probe system
Comparison between the measurement results and
the simulation results of the electron density
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Silicon Drift Detector (SDD) measurement Electron
Temperature

• smaller volume
• high count rate(gt105cps)
• high energy resolution(lt139eV at 5.9keV)
• high quantum efficiency
• operation at room temperature(cooled by Peltier
  element).

Two-channel SDD arrangement
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Conclusion

•       
• In the HL-2A tokamak, the diagnostic systems with
  good spatial resolution have been equipped for
  electron density profiles, electron temperature
  profiles, thermal radiation profiles, soft x-ray
  intensity profiles and H-alpha spectra.
• In order to obtain higher signal and noise ratio,
  a 6-meter HCN wave-guide laser has been designed.
  
• The microwave reflectometry has been installed
  for particle transport investigation.
• The three step electrostatic probes have be
  proved to be a very good tool for studying the
  features of the zonal flows at the edge of the
  HL-2A tokamak plasma for first time.
• In the next step, we will develop the new
  diagnostics for ion temperature profiles, plasma
  current density profiles and impurity profiles.
  To obtain these parameters the Charge Exchange
  Recombination, MSE and multi-channel VUV
  spectrometer are being considered.

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THANK YOU FOR YOUR ATTENTION