Development and preliminary results of phase contrast imaging diagnostic on HL-2A

• Published in: Fusion engineering and design Vol. 139; pp. 104 - 108
• Main Authors: Gong, S.B., Yu, Y., Xu, M., Sun, A.P., Lan, T., Liu, H., Zhong, W.L., Shi, Z.B., Wang, H.J., Wu, Y.F., Yuan, B.D., Mao, S.F., Ye, M.Y., Duan, X.R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2019; Elsevier Science Ltd
• Subjects: Broadband; Carbon dioxide; Carbon dioxide lasers; Diagnostic systems; Magnetic probes; Magnetohydrodynamics; PCI; Phase contrast; Phase shift; Plasma; Plasma density; Plasma density fluctuations; Sound sources; Stability; Temporal resolution; Tokamak devices; Variation; Phase shift; Plasma density fluctuations; PCI
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2019.01.015

•A laser based phase contrast imaging diagnostic has been developed on HL-2 A.•Frequency and wavenumber range are 1 kHz ˜ 500 kHz and 2 cm−1 ˜ 15 cm-1.•A special designed imaging platform is constructed to ensure stability.•Comparison with magnetic probe data shows the reliability of this PCI diagnostic. Phase Contrast Imaging (PCI) diagnostic has been developed on HL-2 A tokamak. The chord integral density fluctuations of plasma can be obtained by measuring the phase shift of CO2 laser which has a wavelength of 10.6 μm after passing through plasma. The 32-channel detector array enables PCI to diagnose density fluctuations with wavenumbers ranging from 2 cm−1 to 15 cm−1. The temporal resolution of PCI is better than 2 μs which makes it suitable for broadband turbulence research. Calibration by the sound source confirms that PCI is able to discriminate a wide range of wavenumbers. The plasma density fluctuations measured by PCI on HL-2 A is presented for the first time. Comparison of MHD instability investigations with magnetic probe data shows the reliability of this PCI diagnostic.