Ph. Mertens
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View article: Diagnostics: Chapter 8 of the special issue: on the path to tokamak burning plasma operation
Diagnostics: Chapter 8 of the special issue: on the path to tokamak burning plasma operation Open
This chapter presents the activity conducted by the ITPA topical group (TG) on Diagnostics over about the last 15 years. Following a general introduction of the ITER Diagnostics led by their measurement roles, the document is organized in …
View article: The radiated power limit in impurity seeded JET-ILW plasmas
The radiated power limit in impurity seeded JET-ILW plasmas Open
The total radiated fraction is examined in high density H-mode plasmas (Greenwald fraction of about 85 %) in JET by the variation of the auxiliary heating power of Pheat = 14 MW-29 MW. An achieved radiation fraction of about 75 % at most h…
View article: Plasma parameters and tungsten sputter rates in a high-frequency CCP
Plasma parameters and tungsten sputter rates in a high-frequency CCP Open
Monitoring and investigating the fusion plasma in ITER will be crucial to pave the way to a fusion power plant. However, the harsh conditions in the vacuum vessel are detrimental for the optical diagnostics systems. Replacing the element w…
View article: Understanding tungsten erosion during inter/intra-ELM periods in He-dominated JET-ILW plasmas
Understanding tungsten erosion during inter/intra-ELM periods in He-dominated JET-ILW plasmas Open
Tungsten erosion was quantified during inter/intra-ELM periods in He-dominated JET-ILW plasmas by optical emission spectroscopy. The intra-ELM tungsten sputtering in helium plasmas, which dominates the total W source, prevails by a factor …
View article: Erosion and screening of tungsten during inter/intra-ELM periods in the JET-ILW divertor
Erosion and screening of tungsten during inter/intra-ELM periods in the JET-ILW divertor Open
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 decr…
View article: Monitoring Removal of W Layer from Ag Substrate Using Balmer-α Emission of Backscattered Hydrogen Atoms in Low Density Gas Discharge
Monitoring Removal of W Layer from Ag Substrate Using Balmer-α Emission of Backscattered Hydrogen Atoms in Low Density Gas Discharge Open
The Doppler-Shifted Reflectance Measurements diagnostic is applied for in-situ measurements of a total spectral reflectance of the sample during the transition phase induced by physical sputtering of a layer of tungsten (W) from an silver …
View article: Peculiarity of highly radiating multi-impurity seeded <i>H</i>-mode plasmas on JET with ITER-like wall
Peculiarity of highly radiating multi-impurity seeded <i>H</i>-mode plasmas on JET with ITER-like wall Open
| openaire: EC/H2020/633053/EU//EUROfusion
View article: Emission of Fast Hydrogen Atoms in a Low Density Gas Discharge—The Most “Natural” Mirror Laboratory
Emission of Fast Hydrogen Atoms in a Low Density Gas Discharge—The Most “Natural” Mirror Laboratory Open
In this work, we present a new application for the line shapes of emission induced by reflected hydrogen atoms. Optical properties of the solids in contact with the plasma could be effectively measured at the wavelength of Balmer lines: ti…
View article: Polarization by light reflection at metallic surfaces observed in the shape of the Balmer-<i>α</i> line of low density plasmas
Polarization by light reflection at metallic surfaces observed in the shape of the Balmer-<i>α</i> line of low density plasmas Open
The degree of linear polarization of light reflected at metallic surfaces is obtained from the shape of the Balmer-α line measured in a low density plasma. The measurements of the polarization properties of metallic surfaces utilize only t…
View article: The software and hardware architecture of the real-time protection of in-vessel components in JET-ILW
The software and hardware architecture of the real-time protection of in-vessel components in JET-ILW Open
For the first time, the JET operation in deuterium-tritium (D-T) plasma, which is scheduled to take place on JET in 2020, will be performed in the ITER mix of plasma-facing component materials. In view of the preparation of the DT campaign…
View article: Determination of tungsten sources in the JET-ILW divertor by spectroscopic imaging in the presence of a strong plasma continuum
Determination of tungsten sources in the JET-ILW divertor by spectroscopic imaging in the presence of a strong plasma continuum Open
The identification of the sources of atomic tungsten and the measurement of their radiation distribution in front of all plasma-facing components has been performed in JET with the help of two digital cameras with the same two-dimensional …
View article: Real-time protection of the JET ITER-like wall based on near infrared imaging diagnostic systems
Real-time protection of the JET ITER-like wall based on near infrared imaging diagnostic systems Open
| openaire: EC/H2020/633053/EU//EUROfusion
View article: <i>In situ</i> measurements of the spectral reflectance of metallic mirrors at the <i>H</i> <i>α</i> line in a low density Ar–H plasma
<i>In situ</i> measurements of the spectral reflectance of metallic mirrors at the <i>H</i> <i>α</i> line in a low density Ar–H plasma Open
The efficient and reliable control and monitoring of the quality of the optical properties of mirrors is an open problem in laboratory plasmas. Until now, the measurement of the reflectance of the first mirrors was based on the methods tha…
View article: The near infrared imaging system for the real-time protection of the JET ITER-like wall
The near infrared imaging system for the real-time protection of the JET ITER-like wall Open
This paper describes the design, implementation and operation of the near infrared (NIR) imaging diagnostic system of the JET ITER-like wall (JET-ILW) plasma experiment and its integration into the existing JET protection architecture. The…
View article: The effect of the isotope on the H-mode density limit
The effect of the isotope on the H-mode density limit Open
In order to understand the mechanisms for the H-mode density limit in machines with fully metallic walls, systematic investigations of H-mode density limit plasmas in experiments with deuterium and hydrogen external gas fuelling have been …
View article: Mechanical pre-dimensioning and pre-optimization of the tokamaks’ toroidal coils featuring the winding pack layout
Mechanical pre-dimensioning and pre-optimization of the tokamaks’ toroidal coils featuring the winding pack layout Open
The structural integrity of superconducting magnets that are key elements of a fusion reactor must be ensured. At an early design stage relatively simple calculation tools can greatly facilitate design optimization. The main objective of t…
View article: Response of the imaging cameras to hard radiation during JET operation
Response of the imaging cameras to hard radiation during JET operation Open
The analysis of the radiation damage of imaging systems is based on all different types-of aiialoiue/digital cameras with uncooled as well as actively cooled image sensors in the VIS/NIR/MWIR spectral ranges. The Monte Carlo N-Particle (MC…
View article: JUVIL: A new innovative software framework for data analysis of JET imaging systems intended for the study of plasma physics and machine operational safety
JUVIL: A new innovative software framework for data analysis of JET imaging systems intended for the study of plasma physics and machine operational safety Open
A new powerful software framework JUVIL (JET Users Video Imaging Library) has been developed and successfully installed at JET for fast data visualization and advanced analysis of all types of imaging data. The JUVIL framework is based on …
View article: Publisher’s Note: “In-vessel calibration of the imaging diagnostics for the real-time protection of the JET ITER-like wall” [Rev. Sci. Instrum. 87, 11D430 (2016)]
Publisher’s Note: “In-vessel calibration of the imaging diagnostics for the real-time protection of the JET ITER-like wall” [Rev. Sci. Instrum. 87, 11D430 (2016)] Open
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View article: Approaches to Analyze Structural Issues of the European DEMO Toroidal Field Coil System at an Early Design Stage
Approaches to Analyze Structural Issues of the European DEMO Toroidal Field Coil System at an Early Design Stage Open
Because of its ambitious goals, the DEMO project faces many technical challenges. The mechanical performance of the superconducting toroidal field coil (TFC) system is mostly determined by the high electromagnetic forces. A structural eval…
View article: Optical Coatings as Mirrors for Optical Diagnostics
Optical Coatings as Mirrors for Optical Diagnostics Open
The aim of this work was to provide a comprehensive insight concerning coated films which might be used for first mirrors in ITER. The influence of the mirror crystallite size has been addressed as well as the coating techniques to provide…
View article: Modeling of crack formation after pulse heat load in ITER-grade tungsten
Modeling of crack formation after pulse heat load in ITER-grade tungsten Open
The one-dimensional numerical simulations of the deformation during and after the pulsed heat load are carried out for tungsten manufactured according to ITER specifications. The calculations for stress-relieved tungsten demonstrated the c…