TJ-II:Electron Cyclotron Emission: Difference between revisions

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TJ-II:Electron Cyclotron Emission (view source)

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Electron cyclotron emission measurements are routinely performed in TJ-II stellarator by means of a multichannel heterodyne radiometer. The radiometer is absolutely calibrated and measures the temperature profile with high temporal resolution.  
Electron temperature profiles are measured at [[TJ-II]]
The diagnostic provides 12 measurement channels, corresponding to 12 values of the major radius ''R''.
by means of a 16 channel heterodyne radiometer,
covering the frequency range 50–60 GHz, corresponding to the second harmonic of electron cyclotron emission (ECE) in X-mode polarization at a magnetic field of 0.95 T on the plasma axis.
The measurements are performed from the low field side (LFS) in the horizontal midplane.
Each frequency corresponds to a different value of the major radius ''R''.
The system is operated close to the strong [[TJ-II:Electron Cyclotron Resonant Heating|ECR heating source]] (f<sub>ECRH</sub> = 53.2 GHz).
To protect the radiometer against stray radiation from the gyrotron, the radiometer band is split into two parts.
The second harmonic emission above and below 53.2 GHz are measured separately by means of microwave couplers in the signal path.
The system is calibrated absolutely by comparing room temperature with liquid nitrogen temperature.  
<ref>[http://link.aip.org/link/?RSINAK/72/379/1 E. de la Luna, J. Sánchez, V. Tribaldos, and T. Estrada, ''Multichannel electron cyclotron emission radiometry in TJ-II stellarator'', Rev. Sci. Instrum. '''72''', 379 (2001)]</ref>
<ref>[http://link.aip.org/link/?RSINAK/72/379/1 E. de la Luna, J. Sánchez, V. Tribaldos, and T. Estrada, ''Multichannel electron cyclotron emission radiometry in TJ-II stellarator'', Rev. Sci. Instrum. '''72''', 379 (2001)]</ref>
<ref>[http://dx.doi.org/10.1016/S0920-3796(00)00492-0 E. de la Luna et al, ''Electron cyclotron emission measurements on TJ-II stellarator plasmas'', Fusion Engineering and Design '''53''', Issues 1-4 (2001) 147-151]</ref>
<ref>[http://dx.doi.org/10.1016/S0920-3796(00)00492-0 E. de la Luna et al, ''Electron cyclotron emission measurements on TJ-II stellarator plasmas'', Fusion Engineering and Design '''53''', Issues 1-4 (2001) 147-151]</ref>
The emission can be simulated by the [[TRECE]] ray tracing code.
The emission can be simulated by the [[TRECE]] ray tracing code.
<ref>[http://dx.doi.org/10.1088/0029-5515/36/3/I02 V. Tribaldos and B. P. van Milligen, ''Electron cyclotron emission calculations for TJ-II stellarator'', Nucl. Fusion '''36''', 283 (1996)]</ref>
<ref>[http://dx.doi.org/10.1088/0029-5515/36/3/I02 V. Tribaldos and B. P. van Milligen, ''Electron cyclotron emission calculations for TJ-II stellarator'', Nucl. Fusion '''36''', 283 (1996)]</ref>
The sampling rate is 100 kHz.
The typical sampling rate is 100 kHz.
The signals are called 'ECE1' ... 'ECE12' in the [[TJ-II:Shot_database|TJ-II database]].
The signals are called 'ECE1' ... 'ECE16' in the [[TJ-II:Shot_database|TJ-II database]].
The measured ECE amplitude is proportional to the electron temperature, provided certain conditions are met.
The measured ECE amplitude is proportional to the electron temperature, provided certain conditions are met.


== References ==
== References ==
<references />
<references />
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