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Introduction of Lower Port 02 integration and its function and requirement for tenant diagnostic, Divertor Impurity Monitor. And Guide structure and Rack locking mechanism are described to achieve the tolerances requirement from tenant diagnostic. And Mock-up and plan for the structures are introduced., 41st Meeting of the ITPA Topical Group on Diagnostics

The ITER Edge Thomson scattering system provides measurements of the electron temperature and density profiles at the periphery plasma of the ITER tokamak for physics studies and advanced plasma control. The front-end of the system contains a relatively large 23 cm × 25.8 cm metal first mirror (FM). Radio-frequency plasma is considered to remove contaminants from the FM. The new design approach for the power transmission circuit for plasma cleaning includes a pre-matching element next to the FM and a notch-filter. The FM is water-cooled and the water cooling pipe length is tuned as a notch filter for the driving frequency. The power dissipation in the circuit elements was analyzed in a series of simulations at frequencies 30, 40 and 50 MHz. New plasma impedance values used for the model were measured in argon and helium plasma at 1–10 Pa in a special mock-up of the front-end optics compartment. The results define inductance, capacitance and geometry of pre-matching elements and help to predict the performance of the plasma cleaning circuit.

This study developed a new correction method to reduce errors in temperature measurement caused by temperature-dependent emissivity for ITER divertor infrared (IR) thermography. In order to develop the method, we measured the spectral emissivity of tungsten from 200 °C to 1900 °C in the wavelength range of 1.5 μm to 4.5 μm and evaluated temperature measurement error of the two-color method. The results indicate that temperature-dependent emissivity is a major factor in temperature measurement errors, which suggests that accurately measuring temperature by using the conventional two-color method would prove difficult. The new correction method uses two emissivity inputs at different temperature points, in contrast to the conventional method, which uses emissivity measured at a single temperature point. Using this new correction method with a suitable wavelength combination for the two-color method, temperature measurement error was reduced to less than 5% at 1900 °C.

真空容器内のITER下部ポート統合機器の中性子遮蔽体は、計測機器を搭載する計測機器構造体とバックプレートで構成されている。 この論文では、ステンレス製の缶に炭化ホウ素粉末を充填した新しい中性子遮蔽体のコンセプトを提案する。 このコンセプトを実証するためにプロトタイプが製作され、プロトタイプの炭化ホウ素の密度は1915 kg / m3に達し、実際の密度2520 kg / m3の76％に達することが確認された。 核解析には、プロトタイピングによって確認された密度を適用した。その結果、45 µSv / hの運転停止後線量率（SDDR）が達成され、ITERの要求値を満足した。

This study developed a new heat flux reconstruction code based on the dual reciprocity boundary element method for the International Thermonuclear Experimental Reactor (ITER) divertor infrared (IR) thermography system. To use divertor heat flux reconstruction in ITER, we modeled the boundary condition between the coolant pipe inner wall and the coolant based on the temperature-dependent heat transfer coefficient and also considered the temperature dependence of tungsten thermal properties. Using this reconstruction code, we evaluated the sensitivity of the input data errors, divertor coolant temperature, and surface temperature errors on the accuracy of heat flux reconstruction by using simplified heat flux profiles, which are spatially uniform on the top surface of the monoblocks. This heat flux reconstruction method demonstrated that highly accurate heat flux reconstruction can be achieved for high heat flux cases in ITER; however, further studies are needed for low heat flux reconstruction.

This paper reports the gamma-ray irradiation effects on optical coatings and polarizers to be used in the ITERedge Thomson scattering system (ETS). Outside a diagnostic port-plug, in the Interspace, a total dose of the orderof 1 MGy is expected through 20 years of ITER operation. In this study, gamma-ray irradiation experiments wereperformed up to 10 MGy. A high peak power laser beam, i.e. a pulse energy of 5 J and a pulse duration of∼4 ns,is needed for a Thomson scattering measurement in ITER. Laser-induced damage threshold (LIDT) of anti-re-flection (AR) and high-reflection (HR) coatings at the laser wavelengths after gamma-ray irradiation were in-vestigated. LIDT of AR coating for 0° injections was more likely higher for the irradiated samples at a wavelengthof 1064 nm. Regarding HR coatings, LIDT was not noticeably degraded by gamma-ray irradiation. Regardingpolarizers, no degradation of transmission and extinction ratio was observed at visible and near infrared wa-velength ranges when a wire-grid polarizer substrate is made of fused silica. Since a signal of ETS is almostlinearly polarized, a wire-grid polarizer enables to improve signal to noise ratio of electron temperature anddensity measurements by Thomson scattering in ITER.

The ITER poloidal polarimeter will install optical components, corner cube retro-reflectors, into the slot of the first wall (FW) panels. The issues of designing the retro-reflector were (i) to achieve good thermal contact between the retro-reflector assembly and the FW and (ii) to accommodate the different thermal expansion of the retro-reflector made of tungsten and the FW made of stainless steel. In order to solve the issues, the CuCrZr filler was employed. A coupled mechanical-thermal analysis was carried out to confirm that the required contact pressure of 60 MPa persists during plasma operation. The highest predicted temperature of the retro-reflector was 673 °C, which is acceptable for tungsten. Electromagnetic analysis was carried out to confirm that the retro-reflector assembly will not move during plasma disruption. A maximum force of 3.06 kN is predicted on the retro-reflector during disruption and is much less than the static friction of 136 kN. In addition, the manufacturability of the retro-reflector assembly was successfully demonstrated. The roughness (Ra) and the flatness (root mean square) achieved for the mirror surface were 0.43 nm and 0.068 μm, respectively. The angle between the assembled mirrors was 90 ± 0.03°, better than the requirement of 90 ± 0.05°.

A new high speed Nd:YAG Thomson scattering AD Convertor (HYADC) that can directly convert the detected scattered light signal into a digital signal is under development. The HYADC is expected to improve a signal to noise ratio of the Nd:YAG Thomson scattering measurement. The data storage of the HYADC which is required for the direct conversion of whole plasma discharge is drastically reduced by a ring buffer memory and a stop trigger system. Data transfer of the HYADC is performed by the SiTCP. The HYADC is easily expandable to a multi-channel system by the distributed data processing, and is very compact and easy to implement as a built-in system of the polychromators.

For the satellite tokamak JT-60 Super Advanced (JT-60SA), a divertor Thomson scattering measurement system is planning to be installed. In this study, we improved the design of the collection optics based on the previous one, in which it was found that the solid angle of the collection optics became very small, mainly because of poor accessibility to the measurement region. By improvement, the solid angle was increased by up to approximately five times. To accurately assess the measurement performance, background noise was assessed using the plasma parameters in two typical discharges in JT-60SA calculated from the SONIC code. Moreover, the influence of the reflection of bremsstrahlung radiation by the wall is simulated by using a ray tracing simulation. The errors in the temperature and the density are assessed based on the simulation results for three typical field of views.

This paper reports the first results of collaborative experiments in JT-60U and JET to compare ELMy H-mode characteristics in the two machines. The JT-60U/JET identity experiments were aimed explicitly at matching edge pedestal parameters in plasmas of the same geometry. The similar size of the two devices allows plasma configurations and conditions to be established for which the match of the dimensionless parameters (ρ*, ν*, β and q 95 ) and of the equilibrium geometry is carried out in plasmas that are also almost identical in dimensional terms. The results of the power and density scans at fixed (and matched) I p - B T show that, in a common range of ρ*, the pedestal electron collisionality, ν* e , and normalized pressure, β p,ped do not match in the two machines, against expectations. In particular, the range of β p,ped of JT-60U ELMy H-modes with Type I ELMs is accessible to JET plasmas only with a Type III ELM edge, and ν* e in JT-60U is consistently higher by 2 than in JET, for the same ρ*. A comparison of n e and T e pedestal profiles indicates that ⊇T e is comparable in the two devices, while JET n e profiles are steeper than JT-60U. The global energy confinement enhancement factor (H98y-2) is higher in JET than in JT-60U, and part of this difference is attributed to the reduced pedestal pressure in JT-60U compared with JET.

In this study, we investigate designs for polychromators of the ITER edge Thomson scattering system by means of numerical calculations. For this purpose, we discuss the optimum transmission wavelength ranges of the optical filters and the optimum number of filters. Five different filter arrangements, including those with an optical notch filter to eliminate D(alpha) emission, are compared with each other. The measurement accuracy when using a polychromator is evaluated for midplane port configuration. It is found that the optimum filter number keeping in mind the cost performance cost is 5 or 6. Moreover, the use of an optical notch filter increases the measurement accuracy by approximately 5%.