The electron cyclotron emission imaging system on EAST with continuous large observation area

Abstract

A: A 384 channels (24 vertical ×16 radial) Electron Cyclotron Emission Imaging (ECEI) system has been installed on Experimental Advanced Superconducting Tokamak (EAST). With the aid of advanced front optics, high spaital resolution around 1.1cm and flexible vertical coverage 30 ∼ 70 cm have been realized. The well-designed optics also provides a long Rayleigh length up to 70 cm even with an object length larger than 2.6 m. The electronic system has a wide immediate frequency (IF) bandwidth 2 ∼ 16.5 GHz, which enables a continuous radial coverage up to 25 cm. Benefited from advanced optics design and the wide IF bandwidth, the ECEI system with high spatial resolution can provide a large and continuous view field, especially in the radial direction, which is enough for the observation of the whole q = 1 surface. The comprehensive details of the ECEI system will be presented in this paper, along with some experimental results. K: Nuclear instruments and methods for hot plasma diagnostics; Plasma diagnosticsinterferometry, spectroscopy and imaging 1Corresponding author.

Newly uncovered physics of MHD instabilities using 2-D electron cyclotron emission imaging system in toroidal plasmas

“…The ECEi results show a closer resemblance to the full reconnection model. Since the first measurement of 2-D images of the sawtooth dynamics in TEXTOR, the sawtooth crash process has been studied with the 2-D ECEi system on DIII-D [65], EAST [66], ASDEX-U [67] and HL-2A [68], HT-7 [69] and each reporting that the observations are consistent with the findings from the TEXTOR plasma. The measured 2-D images from the sawtooth crash process in EAST, ASDEX-U and HT-7 are illustrated in Figure. 11a-11c.…”

“…3-D nature] on TFTR [57]. Distortion of the 1/1 kink mode and localization in toroidal plane can be interpreted as a higher harmonic Fourier components of the 1/1 kink mode and there are numerous experimental reports on observation of harmonic modes of the 1/1 kink mode [65][66][67] as shown in Figure 11a-c. In the experiment, sawtooth crashes are dominated by the reconnection event of the highly distorted 1/1 kink mode with non-axisymmetry in the poloidal and toroidal planes and the corresponding crash time is an order of magnitude faster than τ c deduced from the model in a helically axisymmetric system.…”

Bench test of microwave imaging reflectometry system for EAST tokamak

“…For typical discharge of EAST plasma, MIR system with 96 pixels (12 × 8) is able to cover a wide radial range (r/a = 0.41 ∼ 0.99). Together with the installed ECE Imaging system [5] co-located in the same port, the evolutions of the electron density and temperature fluctuations will be simultaneously obtained in the same observation area, shown in figure 1.…”

System-on-chip integrated circuit technology applications on the DIII-D tokamak for multi-field measurements

“…Microwave imaging diagnostics have been developed and applied on major magnetic confinement fusion facilities [1][2][3][4][5][6] for the study of MHD instability, energetic particle instability, microturbulence, transport, disruption avoidance, and ELM physics. Advances in technology bring leaps in diagnostic capabilities.…”