A probabilistic formalism, relying on Bayes’ theorem and linear Gaussian inversion, is adapted, so that a monochromatic problem can be investigated. The formalism enables an objective test in probabilistic terms of t...A probabilistic formalism, relying on Bayes’ theorem and linear Gaussian inversion, is adapted, so that a monochromatic problem can be investigated. The formalism enables an objective test in probabilistic terms of the quantities and model concepts involved in the problem at hand. With this formalism, an amplitude (linear parameter), a frequency (non-linear parameter) and a hyperparameter of the Gaussian amplitude prior are inferred jointly given simulated data sets with Gaussian noise contributions. For the amplitude, an analytical normal posterior follows which is conditional on the frequency and the hyperparameter. The remaining posterior estimates the frequency with an uncertainty of MHz, while the convolution of a standard approach would achieve an uncertainty of some GHz. This improvement in the estimation is investigated analytically and numerically, revealing for instance the positive effect of a high signal-to-noise ratio and/or a large number of data points. As a fixed choice of the hyperparameter imposes certain results on the amplitude and frequency, this parameter is estimated and, thus, tested for plausibility as well. From abstract point of view, the model posterior is investigated as well.展开更多
A Michelson interferometer, on loan from EFDA-JET（Culham, United Kingdom）has recently been commissioned on the experimental advanced superconducting tokamak（EAST,ASIPP, Hefei, China）. Following a successful in-sit...A Michelson interferometer, on loan from EFDA-JET（Culham, United Kingdom）has recently been commissioned on the experimental advanced superconducting tokamak（EAST,ASIPP, Hefei, China）. Following a successful in-situ absolute calibration the instrument is able to measure the electron cyclotron emission（ECE） spectrum, from 80 GHz to 350 GHz in extraordinary mode（X-mode） polarization, with high accuracy. This allows the independent determination of the electron temperature profile from observation of the second harmonic ECE and the possible identification of non-Maxwellian features by comparing higher harmonic emission with numerical simulations. The in-situ calibration results are presented together with the initial measured temperature profiles. These measurements are then discussed and compared with other independent temperature profile measurements. This paper also describes the main hardware features of the diagnostic and the associated commissioning test results.展开更多
文摘A probabilistic formalism, relying on Bayes’ theorem and linear Gaussian inversion, is adapted, so that a monochromatic problem can be investigated. The formalism enables an objective test in probabilistic terms of the quantities and model concepts involved in the problem at hand. With this formalism, an amplitude (linear parameter), a frequency (non-linear parameter) and a hyperparameter of the Gaussian amplitude prior are inferred jointly given simulated data sets with Gaussian noise contributions. For the amplitude, an analytical normal posterior follows which is conditional on the frequency and the hyperparameter. The remaining posterior estimates the frequency with an uncertainty of MHz, while the convolution of a standard approach would achieve an uncertainty of some GHz. This improvement in the estimation is investigated analytically and numerically, revealing for instance the positive effect of a high signal-to-noise ratio and/or a large number of data points. As a fixed choice of the hyperparameter imposes certain results on the amplitude and frequency, this parameter is estimated and, thus, tested for plausibility as well. From abstract point of view, the model posterior is investigated as well.
基金supported by National Natural Science Foundation of China(Nos.11405211,11275233)the National Magnetic Confinement Fusion Science Program of China(Nos.2013GB106002,2015GB101000)+1 种基金the RCUK Energy Programme(No.EP/I501045)partly supported by the JSPS-NRF-NSFC A3 Foresight Program in the Field of Plasma Physics(NSFC:No.11261140328)
文摘A Michelson interferometer, on loan from EFDA-JET（Culham, United Kingdom）has recently been commissioned on the experimental advanced superconducting tokamak（EAST,ASIPP, Hefei, China）. Following a successful in-situ absolute calibration the instrument is able to measure the electron cyclotron emission（ECE） spectrum, from 80 GHz to 350 GHz in extraordinary mode（X-mode） polarization, with high accuracy. This allows the independent determination of the electron temperature profile from observation of the second harmonic ECE and the possible identification of non-Maxwellian features by comparing higher harmonic emission with numerical simulations. The in-situ calibration results are presented together with the initial measured temperature profiles. These measurements are then discussed and compared with other independent temperature profile measurements. This paper also describes the main hardware features of the diagnostic and the associated commissioning test results.
