Update on the status of the ITER ECE diagnostic design

Taylor, G.; Austin, M. E.; Basile, Allan; Beno, J.H.; Danani, S.; Feder, R.; Houshmandyar, Saeid; Hubbard, A.; Johnson, D. W.; Khodak, Andrei; Kumar, Ravinder; Kumar, Siddharth; Ouroua, A.; Padasalagi, Shrishail; Pandya, Hitesh Kumar B.; Phillips, P. E.; Rowan, W. L.; Stillerman, J.; Thomas, Sajal; Udintsev, V. S.; Vayakis, G.; Walsh, Michael J.; Weeks, D.A.

doi:10.1051/epjconf/201714702003

Cited by 15 publications

(9 citation statements)

References 4 publications

(4 reference statements)

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“…However, as stated above, its availability is restricted to the non-active phase of ITER operation. Two other diagnostics that could be used for runaway electron detection during the nuclear phase of operation are ECE [285] and the radial gamma-ray spectrometer [173]. The latter will have a detection limit of 40 kA and time resolution of about 10 ms and can thus be used for early detection of runaway electrons (note that this diagnostic is not fully credited yet).…”

Section: F Runaway Electron Diagnostics In Itermentioning

confidence: 99%

Physics of runaway electrons in tokamaks

et al. 2019

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Of all electrons, runaway electrons have long been recognized in the fusion community as a distinctive population. They now attract special attention as a part of ITER mission considerations. This review covers basic physics ingredients of the runaway phenomenon and the ongoing efforts (experimental and theoretical) aimed at runaway electron taming in the next generation tokamaks. We emphasize the prevailing physics themes of the last 20 years: the hot-tail mechanism of runaway production, runaway electron interaction with impurity ions, the role of synchrotron radiation in runaway kinetics, runaway electron transport in presence of magnetic fluctuations, micro-instabilities driven by runaway electrons in magnetized plasmas, and vertical stability of the plasma with runaway electrons. The review also discusses implications of the runaway phenomenon for ITER and the current strategy of runaway electron mitigation.

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Section: F Runaway Electron Diagnostics In Itermentioning

confidence: 99%

Physics of runaway electrons in tokamaks

et al. 2019

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“…For a specific channel i the predicted signal in bit is described via equation (9). Given a linear sensitivity, this equation can be rewritten to…”

Section: Appendix: Temperature Dependence Of the Predictionmentioning

confidence: 99%

“…The implementation allows easy automation of the whole calibration procedure given a calibration source making multiple reference temperatures available in the torus hall. A hot source could also be used, as planned for ITER 9 .…”

Section: Introductionmentioning

confidence: 99%

Bayesian modeling of microwave radiometer calibration on the example of the Wendelstein 7-X electron cyclotron emission diagnostic

Hoefel

Hirsch

Kwak

et al. 2019

Review of Scientific Instruments

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This paper reports about a novel approach to the absolute intensity calibration of an electron cyclotron emission (ECE) spectroscopy system. Typically, an ECE radiometer consists of tens of separated frequency channels corresponding to different plasma locations. An absolute calibration of the overall diagnostic including near plasma optics and transmission line is achieved with blackbody sources at LN 2 temperature and room temperature via a hot/cold calibration mirror unit. As the thermal emission of the calibration source is typically a few thousand times lower than the receiver noise temperature, coherent averaging over several hours is required to get a sufficient signal to noise ratio. A forward model suitable for any radiometer calibration using the hot/cold method and a periodic switch between them has been developed and used to extract the voltage difference between the hot and cold temperature source via Bayesian analysis. In contrast to the classical analysis which evaluates only the reference temperatures, the forward model takes into account intermediate effective temperatures caused by the finite beam width and thus uses all available data optimally. This allows the evaluation of weak channels where a classical analysis would not be feasible, is statistically rigorous and provides a measurement of the beam width. By using a variance scaling factor a model sensitive adaptation of the absolute uncertainties can be implemented, which will be used for the combined diagnostic Bayesian modelling analysis.

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“…The calibration of the ECE radiometry is the key step in obtaining the absolute or relative Te profile. The conventional calibration method is the in-situ calibration using the blackbody hot source with known temperature and it is utilized on many devices such as JET, DⅢ-D, EAST, and ITER (in the future) [5][6][7][8]. However, the blackbody hot source method is complex and inflexible because it requires a long time operation (tens of minutes or even hours) and a large space to operate.…”

Section: Introductionmentioning

confidence: 99%

Upgrade of the relative calibration methods and Bayesian inference processing for electron cyclotron emission radiometry

Shi

Yang

et al. 2023

EPJ Web Conf.

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An upgraded local oscillator (LO) hopping calibration method based on a blackbody hot source and a perturbation analysis of the magnetic field difference method are introduced in this work. The blackbody hot source is used to evaluate the difference in the relative coefficients between the two LO hopping frequencies in the same channels. Then the coefficients are obtained by multiplying the LO hopping frequencies coefficients by LO hopping calibration coefficients. In this way, it is more flexible and stable than the in-situ calibration. The magnetic field difference method provides another calibration method to obtain the relative calibration coefficients of the electron cyclotron emission radiometers (ECE). In general, the magnetic field difference method needs two similar shots but with a difference of 2.1% (for HL-2M) in the magnetic field. Meanwhile, there are some errors because of the deviation of detection positions in the same channels between the two shots. For evaluating the calibration errors, the impact of the displacement, Te perturbation of the core region, and magnetic field difference has been discussed. The result shows that a larger magnetic field difference can improve the accuracy of the calibration. In the end, Bayesian inference has been utilized to evaluate the calibration coefficients and get the most probable calibration coefficients along with its the confidence interval.

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Update on the status of the ITER ECE diagnostic design

Cited by 15 publications

References 4 publications

Physics of runaway electrons in tokamaks

Physics of runaway electrons in tokamaks

Bayesian modeling of microwave radiometer calibration on the example of the Wendelstein 7-X electron cyclotron emission diagnostic

Upgrade of the relative calibration methods and Bayesian inference processing for electron cyclotron emission radiometry

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