Plasma Surface Engineering Laboratory

He depth profile measurements on Plasma Facing Components for fusion applications


- National Institute for Lasers Plasma and Radiation Physics, Plasma Physics and Nuclear Fusion Dept. (Project responsible Dr. Eduard GRIGORE)

- Institut de Recherche sur la Fusion par confinement Magnétique, IRFM (Project responsible Dr. Mehdi FIRDAOUS)


The aim of the project is to increase the capability of the GDOES (Glow Discharge Optical Emission Spectrometry) equipment in order to be used as a complementary analysis instrument for assess the helium content within the PFC (Plasma Facing Components) exposed to fusion plasma. In this way the erosion/deposition or retention phenomena of the materials exposed to fusion plasma can be evaluated in a broad manner. A second possible project output will be the production of reference samples (with known He content) that can be used for LIBS (Laser Induced Breakdown Spectrometry) measurements.

In order to address the main objective of the project the following steps will be addressed:

a. Production of He reference samples. The references will be produced in the form of thin films (coatings) with a suitable thickness. The coatings will be deposited by CMSII (Combined Magnetron Sputtering and Ion Implantation) method using a specific technology developed to produce nanoporous coatings. This technology is able to produce nanopores of 10-20 nm within the coatings. Another technology based on HIPIMS (High Impulse Magnetron Sputtering) process will be tested as well in order to produce coatings with high He content. The production of reliable calibration samples will represent the milestone 1 of the project.

b. Measurement of He content by using different analysis methods. Samples with high He content measured and optimized by TDS will be sent to other laboratories for an accurate determination of He content. These measurements will supply the concentrations values of He that will be use in the process of GDOES calibration.

c. Set-up the GDOES analysis method for elemental depth profiling. This phase will imply the identification of the most suitable emission line of He that will be used in the process of the measurement and the setting up the analysis methods. The GDOES analysis implies a glow discharge performed in Ar with the sample to be measured playing the role of the cathode. The elemental analyze is performed by measuring the specific emission line of the element of interest by using a series of photomultipliers positioned in precise positions. For He measurement a monochoromator settled at the wavelength of interest and integrated measurement chain of the spectrometer will be used. In this respect cross checking of the measurements with other technique (NRA and ToF-ERDA) will be very helpful. The calibration of the GDOES equipment for He depth profile will represent the second milestone of the project.

d. Testing of the GDOES method for He quantification in assessment the He profile across tiles subjected to fusion plasma (the third milestone of the project). Tiles subjected to fusion plasma depending on the position inside the fusion reactor and operating regimes are subjected to erosion or deposition phenomena. In the case of erosion tiles. After the calibration process of the GDOES equipment, He containing samples produced by CMSII will be analyzed. The He profile across the coatings will be measured. A special attention will be paid to the measurement of samples (W coated graphite samples) cored from tiles retrieved from WEST. The developed method, with some adjustments can be applied to bulk materials (W, Inconell alloy) subjected to fusion plasma and retrieved from different WEST areas. A specific GDOES method will be developed for W coated CuCrZr tiles.

According to the project workplan in the present stage of the project, the synthesis and characterization of He containing coatings were planned and carried out.


W+He coatings were obtained and their ability to retain He has been measured. The coatings have been deposited by using the CMSII technique by adjusting the deposition parameters in order to get a nanoporous coatings structure. A mixture consisting of Ar+He was used as deposition atmosphere. The compositions of the coatings have been determined by GDOES measurements. The coating thickness was ~ 6 µm.

Further works

Next year activties will continues with the production of He containing coatings by using HIPIMS deposition method. The coatings will be subjected to an optimization programm aimed to increase the retained He content. The optimization will be performed by using TDS measurements. At the end, the best deposition method will be selected in order to produce coatings with high He content, that will be used in the calibration process of the GDOES equipment.