Neutron Shielding Design of Infrared Imaging Video Bolometer for LHD Deuterium Experiment

Abstract

InfraRed imaging Video Bolometer (IRVB) is a powerful diagnostic for the plasma radiation measurement. Study on plasma radiation phenomena, e.g., plasma detachment is one of the crucial issues to realize a fusion reactor. In order to apply the IRVB to such a study, a shielding is required to protect an IR camera from neutron irradiation. In the Large Helical Device (LHD) deuterium experiment has started in 2017. Then, the shielding was designed using MCNP6 code with the threedimensional modelling of LHD. The guideline of the neutron flux for the design was determined by the operational experience in JT-60U tokamak and by the result of the irradiation in OKTAVIAN. The strong neutron flux due to the location close to the vacuum vessel and the influx through the lens hole were reduced sufficiently. The designed shielding was applied to the LHD deuterium experiments and the IRVB with the shielding could be operated successfully without any dead pixels in the neutron emission rate up to 3.3 × 10 15 n×s -1 , which is the maximum rate in the first experimental campaign, and in the total neutron emission of 3.6 × 10 18 n. These correspond to the neutron emission rate of 2.9 × 10 7 n×s -1 and the total neutron emission of 3.2 × 10 10 n at around the IR camera.

Divertor heat load distribution measurements with infrared thermography in the LHD helical divertor

“…The validity and the details regarding the shielding adopted in the present study are well reported in Ref. [14]. The temperature calibration was performed before the LHD experiment campaign by using blackbody calibration source with known emissivity and temperature.…”

Design of a Communication Device of Infrared Thermal Imaging Target Recognition and Tracking System

“…e main disadvantage of the EM algorithm is that it may converge to a local extremum. Fuzzy C-means clustering is computationally expensive [15]. Comprehensive comparison, the K-means clustering algorithm is more suitable for infrared thermal imaging images.…”

“…. m) is the sample point in R d , then the mean shift vector at point x can be defined as equation (15), T l is a high-dimensional spherical area with a radius of l, and satisfies the equation (15). w means that out of the m sample points, w fall into the T l area.…”

Sensitivity improvement of infrared imaging video bolometer for divertor plasma measurement

“…As the result of preliminary measurement in GAMMA10/PDX, temperature rise on the foil absorber was up to 1/5 of LHD. In LHD [11], 𝜎 ! "#$ is 1200 µW/cm 2 without time averaging and signal-to-noise ratio, 𝑆𝑁𝑅 1232 in TABLE II of [12], is 3.4.…”