Abstract
Reconstructing the shape and position of plasma is an important issue in Tokamaks. Equilibrium and fitting (EFIT) code is generally used for plasma boundary reconstruction in some Tokamaks. However, this magnetic method still has some inevitable disadvantages. In this paper, we present an optical plasma boundary reconstruction algorithm. This method uses EFIT reconstruction results as the standard to create the optimally optical reconstruction. Traditional edge detection methods cannot extract a clear plasma boundary for reconstruction. Based on global contrast, we propose an edge detection algorithm to extract the plasma boundary in the image plane. Illumination in this method is robust. The extracted boundary and the boundary reconstructed by EFIT are fitted by same-order polynomials and the transformation matrix exists. To acquire this matrix without camera calibration, the extracted plasma boundary is transformed from the image plane to the Tokamak poloidal plane by a mathematical model, which is optimally resolved by using least squares to minimize the error between the optically reconstructed result and the EFIT result. Once the transform matrix is acquired, we can optically reconstruct the plasma boundary with only an arbitrary image captured. The error between the method and EFIT is presented and the experimental results of different polynomial orders are discussed.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Ahn JW, Maingi R, Mastrovito D, et al., 2010. High speed infrared camera diagnostic for heat flux measurement in NSTX. Rev Sci Instrum, 81(2):023501. https://doi.org/10.1063/1.3297899
Alpers A, Gritzmann P, Moseev D, et al., 2015. 3D particle tracking velocimetry using dynamic discrete tomography. Comput Phys Commun, 187:130–136. https://doi.org/10.1016/j.cpc.2014.10.022
Canny J, 1986. A computational approach to edge detection. IEEE Trans Patt Anal Mach Intell, 8(6):679–698. https://doi.org/10.1109/TPAMI.1986.4767851
Davis WM, Patel RI, Boeglin WU, 2010. Advances in fast 2D camera data handling and analysis on NSTX. Fus Eng Des, 85(3):325–327. https://doi.org/10.1016/j.fusengdes.2010.02.005
Hommen G, Baar MD, Nuij P, et al., 2010. Optical boundary reconstruction of tokamak plasmas for feedback control of plasma position and shape. Rev Sci Instrum, 81(11):113504. https://doi.org/10.1063/1.3499219
Hommen G, de Baar M, Citrin J, et al., 2013. A fast, magnetics-free flux surface estimation and q-profile reconstruction algorithm for feedback control of plasma profiles. Plasma Phys Contr Fus, 55(2):025007. http://stacks.iop.org/0741-3335/55/i=2/a=025007
Hommen G, de Baar M, Duval BP, et al., 2014. Realtime optical plasma boundary reconstruction for plasma position control at the TCV Tokamak. Nucl Fus, 54(7):073018. https://doi.org/10.1088/0029-5515/54/7/073018
Hussain S, Qayyum A, Ahmad Z, et al., 2016. Initial plasma formation in the GLAST-II spherical Tokamak. J Fus Energy, 35(3):529–537. https://doi.org/10.1007/s10894-015-0052-z
Kumar D, Clayton DJ, Parman M, et al., 2012. Dual transmission grating based imaging radiometer for Tokamak edge and divertor plasmas. Rev Sci Instrum, 83(10):10E511. https://doi.org/10.1063/1.4732182
Martin V, Travere JM, Bremond F, et al., 2010. Thermal event recognition applied to protection of Tokamak plasma-facing components. IEEE Trans Instrum Meas, 59(5):1182–1191. https://doi.org/10.1109/TIM.2009.2038032
Mitteau R, Spruytte J, Vallet S, et al., 2007. A possible method of carbon deposit mapping on plasma facing components using infrared thermography. J Nucl Mater, 363-365:206–210. https://doi.org/10.1016/j.jnucmat.2007.01.009
Munsat T, Zweben SJ, 2006. Derivation of time-dependent two-dimensional velocity field maps for plasma turbulence studies. Rev Sci Instrum, 77(10):103501. https://doi.org/10.1063/1.2356851
Odstrcil M, Mlynár J, Weinzettl V, et al., 2013. Dust observation in the compass Tokamak using fast camera. 22nd Annual Conf of Doctoral Students, p.73–79.
Perek P, 2013. High-performance image processing system for plasma diagnostics. Int PhD Workshop OWD, p.328–331.
Pironti A, Walker M, 2005. Fusion, Tokamaks, and plasma control: an introduction and tutorial. IEEE Contr Syst, 25(5):30–43. https://doi.org/10.1109/MCS.2005.1512794
Qi P, Li Q, Luo GN, 2008. Application of infrared thermography in NDT of plasma-facing components for Tokamaks. 17th World Conf on Non-destructive Testing, p.1–8.
Xue E, Luo J, Shu S, et al., 2011. Plasma edge detection and tracking in the east superconducting Tokamak discharge. 3rd Int Conf on Measuring Technology and Mechatronics Automation, p.865–868. https://doi.org/10.1109/ICMTMA.2011.499
Zhang Z, 2000. A flexible new technique for camera calibration. IEEE Trans Patt Anal Mach Intell, 22(11):1330–1334. https://doi.org/10.1109/34.888718
Zhu Y, Xie J, Liu WD, et al., 2016. The general optics structure of millimeter-wave imaging diagnostic on Tokamak. J Instrum, 11(1):P01004. https://doi.org/10.1088/1748-0221/11/01/P01004
Zweben SJ, McChesney J, Gould RW, 2011. Optical imaging of edge turbulence in the Caltech Tokamak. Nucl Fus, 23(6):825–830. https://doi.org/10.1088/0029-5515/23/6/010
Author information
Authors and Affiliations
Corresponding author
Additional information
Project supported by the National Natural Science Foundation of China (Nos. 61375049 and 61473253)
Rights and permissions
About this article
Cite this article
Luo, H., Luo, Zp., Xu, C. et al. Optical plasma boundary reconstruction based on least squares for EAST Tokamak. Frontiers Inf Technol Electronic Eng 19, 1124–1134 (2018). https://doi.org/10.1631/FITEE.1700041
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1631/FITEE.1700041