A low-voltage ionization chamber for the ITER

An ionization chamber with an operating supply voltage of 10 V has been designed for use at the ITER. The sensitivity of the chamber filled with air at atmospheric pressure is 100–200 times higher than the sensitivity of the chamber pumped down to a pressure of 10⁻³–10⁻⁴ Torr. It is shown that application of the supply voltage modulation technique allows the pickup noise to be substantially reduced; as a result, the amplifier can be located at a large (70–100 m) distance from the chamber. Results of the experiments aimed at testing this technique on the T-10 facility are described. Original Russian Text ? Yu.V. Gott, M.M. Stepanenko, 2009, published in Pribory i Tekhnika Eksperimenta, 2009, No. 2, pp. 117–121.     

Development of two color laser diagnostics for the ITER poloidal polarimeter

Two color laser diagnostics using terahertz laser sources are under development for a high performance operation of the Large Helical Device and for future fusion devices such as ITER. So far, we have achieved high power laser oscillation lines simultaneously oscillating at 57.2 and 47.7?μm by using a twin optically pumped CH(3)OD laser, and confirmed the original function, compensation of mechanical vibration, of the two color laser interferometer. In this article, application of the two color laser diagnostics to the ITER poloidal polarimeter and recent hardware developments will be described.     

Development and irradiation test of lost alpha detection system for ITER

We developed a lost alpha detection system to use in burning plasma experiments. The scintillators of Ag:ZnS and polycrystalline Ce:YAG were designed for a high-temperature environment, and the optical transmission line was designed to transmit from the scintillator to the port plug. The required optical components of lenses and mirrors were irradiated using the fission reactor with the initial result that there was no clear change after the irradiation with a neutron flux of 9.6×10(17)?nm(-2) s(-1) for 48 h. We propose a diagnostic of alpha particle loss, so-called alpha particle induced gamma ray spectroscopy. The initial laboratory test has been carried out by the use of the Ce doped Lu(2)SiO(5) scintillator detector and an Am-Be source to detect the 4.44 MeV high energy gamma ray due to the (9)Be(α,nγ)(12)C reaction.     

On the study of the stress-strain state of the IVV.10M reactor vessel and in-vessel components under seismic impacts

The problem of the seismic stability of the new IVV.10M research reactor is considered. To computationally prove the viability of the engineering solutions, a detailed finite element model of a reactor is developed in strict accordance with the design documentation. The model represents the actual interrelations between all load-carrying elements and loads acting on the structure. A computational investigation of the stress-strain state of a reactor is carried out using the ANSYS bundled software. The natural oscillation frequencies and natural mode shapes of the structure are determined by linear-spectral analysis. The dynamic impacts occurring under seismic conditions are computed taking into consideration the actual response spectra. The most heavily loaded sectors in the reactor vessel and in-vessel components are established. A quantitative assessment of the stress-strain-state parameters in the crucial regions of the reactor is carried out. The computational results are compared with the figures of the normative documents currently in force in domestic nuclear-power engineering.     

Defining the infrared systems for ITER

The International Thermonuclear Experimental Reactor will have wide angle viewing systems and a divertor thermography diagnostic, which shall provide infrared coverage of the divertor and large parts of the first wall surfaces with spatial and temporal resolution adequate for operational purposes and higher resolved details of the divertor and other areas for physics investigations. We propose specifications for each system such that they jointly respond to the requirements. Risk analysis driven priorities for future work concern mirror degradation, interfaces with other diagnostics, radiation damage to refractive optics, reflections, and the development of calibration and measurement methods for varying optical and thermal target properties.     

Development of a Concept of Reflectometric Diagnostics for the ITER Tokamak for Plasma Probing from the High-Magnetic-Field Side

The capabilities of the reflectometric diagnostics in the ITER facility during plasma probing from the high-magnetic-field side are investigated. This technique allows measurements of the density profile and the plasma turbulence-rotation velocity at the lower extraordinary wave from a plasma with a critical density to the center of the plasma column. The system also allows one to probe the plasma column at the ordinary wave. It is proposed to use a combined mirror–horn antenna system. Under conditions where there is limited space for placing horns, this results in a significant (up to 20 dB) increase in the signal, compared to the system of two horns considered earlier. The results of calculations on optimizing the elements of the waveguide transmission line using a two-dimensional full-wave code are presented. The possibility of employing the Doppler effect to study plasma rotation by using antennas for controlling the shape of the plasma column while performing reflectometry at the lower extraordinary wave is considered. This effect is estimated theoretically in the actual ITER plasma configuration.     

基于CATIA二次开发的ITER杜瓦参数化设计研究

杜瓦的设计水平直接影响着杜瓦的质量和性能.在设计装配中采用先进的生产方式和管理方式,才能提高杜瓦生产制造的技术水平.基于CATIA二次开发平台,应用参数化设计建模理论,开发用于杜瓦参数化设计和管理的平台,达到可依据用户需要进行ITER杜瓦的快速变参数设计.该方法对提高杜瓦的设计效率和质量有积极的意义.     

Development of a realistic photonic modeling for the evaluation of infrared reflections in the metallic environment of ITER

In nuclear fusion experiments, the plasma facing components are exposed to high heat fluxes and infrared (IR) imaging diagnostics are routinely used for surveying their surface temperature for preventing damages. However the future use of metallic components in the ITER tokamak adds complications in temperature estimation. Indeed, low and variable emissivity of the observed surface and the multiple reflections of the light coming from hot regions will have to be understood and then taken into account. In this paper, a realistic photonic modeling based on Monte Carlo ray-tracing codes is used to predict the global response of the complete IR survey system. This also includes the complex vessel geometry and the thermal and optical surface properties using the bidirectional reflectivity distribution function that models the photon-material interactions. The first results of this simulation applied to a reference torus are presented and are used as a benchmark to investigate the validity of the global model. Finally the most critical key model parameters in the reflected signals are identified and their contribution is discussed.     

A Multichannel Neutron Collimator for the ITER Tokamak

A concept for the multichannel neutron collimator of the ITER is presented. The design of the collimator is based on the use of a 12-collimator radial neutron camera that was developed earlier and two complementary compact neutron cameras. It is proposed that the compact neutron cameras be placed inside the shielding blocks located in the equatorial (nine collimators) and diverter diagnostic (seven collimators) ITER ports. The plasma would thereby be fully covered in the vertical direction, and the total number of collimator channels would be 21 (12 channels in the radial camera and nine channels in the compact camera). The collimator length and diameters, as well as the optimal materials for the shielding blocks and the inner walls of the collimators, were determined using the MCNP code. It is shown by simulation that, for an adequate collimation of neutron fluxes to be achieved, the collimators should be 1.0–1.5 m long, have an i.d. of 4–5 cm, and be enclosed in a water–iron shielding. It is proposed that threshold fission chambers based on ²³⁸U and natural- and CVD-diamond detectors be used as the sensors. The computations are presented to demonstrate that this composition and arrangement of the channels in the radial and compact cameras makes it possible to measure the two-dimensional spatial distribution of the neutron source and the total thermonuclear power to an accuracy of 10%.     

Electron cyclotron emission diagnostic for ITER

Electron temperature measurements and electron thermal transport inferences will be critical to the nonactive and deuterium phases of ITER operation and will take on added importance during the alpha heating phase. The diagnostic must meet stringent criteria on spatial coverage and spatial resolution during full field operation. During the early phases of operation, it must operate equally well at half field. The key to the diagnostic is the front end design. It consists of a quasioptical antenna and a pair of calibration sources. The radial resolution of the diagnostic is less than 0.06 m. The spatial coverage extends at least from the core to the separatrix with first harmonic O-mode being used for the core and second harmonic X-mode being used for the pedestal. The instrumentation used for the core measurement at full field can be used for detection at half field by changing the detected polarization. Intermediate fields are accessible. The electron cyclotron emission systems require in situ calibration, which is provided by a novel hot calibration source. The critical component for the hot calibration source, the emissive surface, has been successfully tested. A prototype hot calibration source has been designed, making use of extensive thermal and mechanical modeling.     

Strategy for the absolute neutron emission measurement on ITER

Accuracy of 10% is demanded to the absolute fusion measurement on ITER. To achieve this accuracy, a functional combination of several types of neutron measurement subsystem, cross calibration among them, and in situ calibration are needed. Neutron transport calculation shows the suitable calibration source is a DT/DD neutron generator of source strength higher than 10(10)?n/s (neutron/second) for DT and 10(8)?n/s for DD. It will take eight weeks at the minimum with this source to calibrate flux monitors, profile monitors, and the activation system.     

A prototype of the centrifugal pellet injector for the ITER tokamak

A continuous action injector of solid hydrogen pellets with a centrifugal accelerator and a screw extruder is described. Over a long period of time (>3 h), the injector is capable of continuously forming with a 1-Hz frequency solid hydrogen pellets ～2.5 mm in diameter and accelerating them to a velocity of 100–500 m/s with a reliability of >95%. The characteristics of the injector meet the requirements to the ITER tokamak.     

The tri-band high-resolution spectrometer for the ITER CXRS diagnostic system

A tri-band high-resolution spectrometer, which was designed for performing diagnostics on the ITER facility using the charge-exchange recombination spectroscopy (CXRS), is described. The CXRS allows measurements of such plasma parameters as the ion temperature, the speed of the toroidal and poloidal plasma rotation, and the concentration of light impurities. The spectrometer is based on three transparent holographic diffraction gratings and is designed to operate simultaneously in three spectral bands: 468 ± 6 nm, 529 ± 6 nm, and 656 ± 8 nm. The results of measuring the main performance parameters of the transparent diffraction gratings and the spectrometer as a whole are presented. It was established that the characteristics of the developed spectrometer satisfy the requirements for the spectroscopic equipment for the ITER CXRS diagnostic system.     

复杂曲面零件在线检测系统的开发与应用

复杂曲面零件特别是大型零件加工精度检测问题是先进制造技术领域急需解决的重要问题.数控机床在线检测技术则是实现被加工零件加工精度检测的新手段,因其方便、快捷、无需二次装夹,具有良好的应用前景.给出了面向复杂曲面零件加工精度在线检测的系统总体结构,描述了系统所包含的主要功能模块,给出了系统开发中需要解决的测点分布、测量路径生成与仿真、测量误差补偿等模块的实现方法和技术路线.     

Terrace retro-reflector array for poloidal polarimeter on ITER

A new concept of a terrace retro-reflector array (TERRA) as part of the poloidal polarimeter for ITER is proposed in this paper. TERRA reflects a laser light even from a high incident angle in the direction of the incident-light path, while a conventional retro-reflector array cannot. Besides, TERRA can be installed in a smaller space than a corner-cube retro-reflector. In an optical sense, TERRA is equivalent to a Littrow grating, the blaze angle of which varies, depending on the incident angle. The reflected light generates a bright and dark fringe, and the bright fringe is required to travel along the incident-light path to achieve the objects of laser-aided diagnostics. In order to investigate the propagation properties of laser light reflected by TERRA, we have developed a new diffraction formula. Conditions for the propagation of the bright fringe in the direction of the incident light have been obtained using the Littrow grating model and have been confirmed in a simulation applying the new diffraction formula. Finally, we have designed laser transmission optics using TERRA for the ITER poloidal polarimeter and have calculated the light propagation of the system. The optical design obtains a high transmission efficiency, with 88.6% of the incident power returned. These results demonstrate the feasibility of applying TERRA to the ITER poloidal polarimeter.     

A Vacuum Photoemission Detector for X-ray Tomography on the ITER Facility

A vacuum photoemission detector designed for plasma tomography in X rays on the ITER facility is described. Such detectors allow X rays to be detected in the presence of intense neutron and -photon fluxes. The results of tests of a prototype of this detector on a ⁶⁰Co source of rays, its calibration using radiation from an X-ray tube, and tests of its serviceability on the T-10 facility are presented. The values of the valid signal and the signal-to-noise ratio are assessed for the parameters of the ITER facility. Selecting the number of detectors and their arrangement on the ITER facility to ensure the required spatial resolution of the diagnostics is considered.     

Application of the trial-and-error method for solving the inverse radon problem for ITER neutron tomography

A method for solving the inverse 2D Radon problem for a single temporal cross section as applied to the two-aspect-angle ITER neutron tomographic detection system is described. This method allows reduction of the calculation time owing to the formation of the reconstructed image described by models that are as simple as possible in the case of a single plasma filament (a spatial density distribution of the plateau, hill, crater, and banana type). These models are reduced to the approximation of the solution in the form of a superposition of two elliptic Gaussian curves (or the sum of an arbitrary number of circular Gaussian curves).     

ITER运输车双密封门结构静力学分析

根据ITER运输车双密封门的结构特点,在三种工况下选择两种不同的材料,应用有限元分析软件ANSYS对密封门典型部件进行建模和结构静力学分,并考察LY12和SS316L(N)这两种材料在三种工况下的应力和变形情况.有限元的分析结果给下一步的优化设计和结构选材提供了参考.     

Diagnostics of the ITER neutral beam test facility

The ITER heating neutral beam (HNB) injector, based on negative ions accelerated at 1 MV, will be tested and optimized in the SPIDER source and MITICA full injector prototypes, using a set of diagnostics not available on the ITER HNB. The RF source, where the H(-)∕D(-) production is enhanced by cesium evaporation, will be monitored with thermocouples, electrostatic probes, optical emission spectroscopy, cavity ring down, and laser absorption spectroscopy. The beam is analyzed by cooling water calorimetry, a short pulse instrumented calorimeter, beam emission spectroscopy, visible tomography, and neutron imaging. Design of the diagnostic systems is presented.     

Neutron analysis of the ITER vertical neutron camera

The neutron fields in the collimators of a new design for the vertical neutron camera (VNC) of the ITER have been calculated for a standard isotropic bulk DT neutron source. The neutron and gamma-ray spectra and flux densities at the neutron detector sites have been calculated. The signal-to-background ratio of VNC detectors (²³⁸U-based fission chambers and diamond detectors) has been estimated. The signal-to-background ratios versus the threshold energy were calculated for the diamond detectors operating in the threshold counter mode. The effect of background Γ-ray radiation on the performance of the diamond detectors in the VNC environment has been estimated. The radiation heating of the VNC structural components has been calculated. The serviceability of the VNC with the proposed design has been demonstrated.