Search results for "divertor"
showing 10 items of 63 documents
Erosion and screening of tungsten during inter/intra-ELM periods in the JET-ILW divertor
2020
Abstract Intra-ELM tungsten sources, which dominate the total W source, are quantified in the inner and outer divertor of JET-ILW. The amount of the sputtered W atoms for individual ELMs demonstrates a clear dependence on the ELM frequency. It decreases when the pedestal temperature is lower and, correspondingly, the ELM frequency is higher. Nevertheless, the entire gross erosion W source (the number of eroded W atoms per second due to ELMs) increases initially with ELM frequency and reaches its maximum at fELM ≈ 50–55 Hz followed by its reduction in the high frequency range. The in/out asymmetry of the intra-ELM W sources during ELMs is a critical issue and is investigated in this contribu…
Observation of low temperature VUV tungsten emission in JET divertor plasmas
2022
| openaire: EC/H2020/633053/EU//EUROfusion Funding Information: This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 and 2019–2020 under grant agreement No 633053 and from the RCUK Energy Programme [grant number EP/I501045]. The views and opinions expressed herein do not necessarily reflect those of the European Commission. Publisher Copyright: © 2022 The Author(s). Published by IOP Publishing Ltd. The properties of tungsten make it ideal for use as a plasma facing surface in the divertor of large plasma machines such as JET and ITER. However, the intense heat and particle fluxes …
Three-Dimensional Neutronics and Shielding Analyses for the ITER Divertor
1996
3-D neutronics and shielding analyses have been performed for the divertor region of the ITER interim design. The peak neutron wall loading in the divertor region is 0.6 MW/m{sup 2} at the divertor cassette dome. The total nuclear heating in the 60 divertor cassettes is 102.4 MW. The peak helium production in the VV behind the pumping ducts is 0.5 He appm/FPY implying that rewelding might be feasible. The total nuclear heating in the parts of the TF coils in the divertor region is only 2.1 kW. 5 refs., 4 figs., 5 tabs.
Modelling of the magnetic field structures and first measurements of heat fluxes for TEXTOR-DED operation
2004
The dynamic ergodic divertor (DED) was recently installed at the TEXTOR tokamak. One of the aims of the DED is to control and study heat and particle deposition on a plasma wall via modification of the plasma edge by external perturbation coils. Sixteen perturbation coils are mounted on the high-field side of the torus. The external magnetic perturbation creates a zone of chaotic field lines at the plasma edge by destroying several resonant surfaces. These structures have the properties of an open chaotic system while the field lines intersect the tokamak vessel. In order to study the topology of the field lines in different regimes, a set of tools called Atlas was created. Atlas uses a sym…
A computational procedure for the investigation of whipping effect on ITER High Energy Piping and its application to the ITER divertor primary heat t…
2015
Abstract The Tokamak Cooling Water System of nuclear facility has the function to remove heat from plasma facing components maintaining coolant temperatures, pressures and flow rates as required and, depending on thermal-hydraulic requirements, its systems are defined as High Energy Piping (HEP) because they contain fluids, such as water or steam, at a pressure greater than or equal to 2.0 MPa and/or at a temperature greater than or equal to 100 °C, or even gas at pressure above the atmospheric one. The French standards contemplate the need to consider the whipping effect on HEP design. This effect happens when, after a double ended guillotine break, the reaction force could create a displa…
Structural verification and manufacturing procedures of the cooling system, for DEMO divertor target (OVT)
2019
The paper presents the design activities and testing plan of a vertical target mock-up, developed within the pre-conceptual design phase for DEMO Work Package DIV-1 “Divertor Cassette Design and Integration” - EUROfusion Power Plant Physics & Technology (PPPT) program. Activities concerning the Divertor Outboard Vertical Target cooling mock-up are presented in term of CAD model, thermal-hydraulic numerical simulation, structural analysis, structural integrity verification and manufacturing procedure. Moreover, the mechanical dimensions of support systems for Plasma Facing Components (PFCs), manifold and diffuser have been analyzed in detail, in order to avoid structural fault during the tes…
Further improvements in the structural analysis of DEMO Divertor Cassette body and design assessment according to RCC-MRx
2019
Abstract This paper presents the enhancements related to the structural analyses of DEMO Divertor in the framework of the EUROfusion Power Plant Physics & Technology (PPPT) program. This activity started two years ago and its preliminary results were published in previous papers. It has been divided in some areas defined by the similarity of the matters they contain: the structural analysis, of utmost importance, has been preceded by a preliminary phase, like the geometry definition or the thermal and the electric-magnetic analysis for loads evaluation; then the structural analysis has been finally confirmed with further evaluations related to excessive deformation or plastic instability. T…
Steady state and transient thermal–hydraulic analyses on ITER divertor module
2005
Abstract One of the most challenging components of ITER is the divertor devoted at controlling the characteristics of the plasma boundary, exhausting the α particles and reducing the impurities in the plasma. The thermal–hydraulic design of the divertor is particularly, demanding because of the high heat loads and the cooling flow margin in the plasma-facing components (PFCs). The pressure drop is limited by the pumping power and also avoiding the risk of reaching critical heat flux (CHF). Furthermore, for maintenance operation foreseen, each single divertor cassette should be drained and dried before withdrawing it out from the vacuum vessel. To address these requirements, European Fusion …
Comparison of tritium measurement techniques for a laser cleaned JET tile
2014
Abstract Over the last 7–8 years, two quantitative analyzing methods—accelerator mass spectrometry (AMS) and full combustion (FC) followed by scintillation detection have been applied for determining the tritium activity concentrations in JET divertor tiles. These methods have two main differences – the range of detection and the spatial resolution – and are thus complementary. However, these differences can also complicate the comparison of the two techniques for typical JET divertor samples. Therefore a cross comparison exercise for tritium measurements was performed between the two methods using specially produced identical standard samples. The cross comparison measurements were perform…