A protection system for the JET ITER-like wall based on imaging diagnosticsa) Rev. Sci. Instrum. 83, 10D727 (2012); 10.1063/1.4738742Disentangling fluxes of energy and matter in plasma-surface interactions: Effect of process parametersThe knowledge of the effective energy deposited onto a surface by the reactive particles ͑ions, electrons, metastables, photons, etc.͒ in plasma processes such as thin-film deposition, sputtering, etching, etc., is of high interest to understand the basic mechanisms of energy transfer. In this article, a diagnostic is developed to directly measure the global energy transferred to surfaces ͑reactor walls, substrates, material to be modified, etc.͒ immerged in low-pressure plasmas. The diagnostic is based on a commercial HFM7-Vattel® microsensor, confined in a temperature-controlled substrate holder. The manufacturer calibration specifications are only given for atmospheric pressure. They cannot be used in low-pressure plasma conditions ͑typically 0.1-20 Pa͒. Thus, for this particular application, a calibration of the microsensor is required. It is performed at various pressures, between vacuum and the ambient, according to the NIST protocol and using a homemade blackbody ͑BB͒. It is shown that only curves obtained in vacuum or pressures below 0.1 Pa are valuable for a true calibration of the sensor. The others are perturbed by the heating of the gas in the BB surroundings. Measurements carried out in a typical transformer coupled plasma reactor in argon gas are presented. Typically the values are of the order of tens or hundreds of mW/ cm 2 in our experimental conditions. They are consistent with an estimation of the energy transferred by charged particles ͑ions and electrons͒ performed from Langmuir probe characterization of the plasma.

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Thermal properties of two types of porous silicon are studied using the pulsed-photothermal method (PPT). This method is based on a pulsed-laser source in the nanosecond regime. A 1D analytical model is coupled with the PPT technique in order to determinate thermal properties of the studied samples (thermal conductivity and volumetric heat capacity). At rst, a bulk single crystal silicon sample and a titanium thin lm deposited on a single crystal silicon substrate are studied in order to validate the PPT method. Porous silicon samples are elaborated with two dierent techniques, the sintering technique for macroporous silicon and electrochemical etching method for mesoporous silicon. Metallic thin lms are deposited on these two substrates by magnetron sputtering. Finally, the thermal properties of macroporous (30% of porosity and pores diameter between 100 nm and 1000 nm) and mesoporous silicon (30% and 15% of porosity and pores diameter between 5 nm and 10 nm) are determined in this work and it is found that thermal conductivity of macroporous (73 W.m-1 .K-1) and mesoporous (between 80 and 50 W.m-1 .K-1) silicon is two times lower than the single crystal silicon (140 W.m-1 .K-1).

Energy exchanges due to chemical reactions between a silicon surface and a SF 6 plasma were directly measured using a heat flux microsensor. The energy flux evolution was compared with those obtained when only few reactions occur at the surface to show the part of chemical reactions. At 800 W, the measured energy flux due to chemical reactions is estimated at about 7 W.cm -2 against 0.4 W.cm -2 for ion bombardment and other contributions. Time evolution of the HFM signal is also studied. The molar enthalpy of the reaction giving SiF 4 molecules was evaluated and is consistent with values given in literature.a)

International audienceThe ablation threshold and Laser-induced periodic surface structure (LIPSS) formation on copper thin film were investigated using a picosecond laser (Nd:YAG laser: 266 nm, 42 ps, 10 Hz). We show that the ablation threshold varies with respect to the number of laser shots (N) on two different substrates. The single-shot ablation threshold was estimated to be close to 170 ± 20 mJ/cm2. The incubation coefficient was estimated to be 0.68 ± 0.03 for copper thin films on silicon and glass substrates. In addition, morphology changes of the ablated regions, in the same spot area, were studied as a function of fluence and number of laser shots. An intermediate structure occurred with a mix of low spatial frequency LIPSS (LSFL), high spatial frequency LIPSS (HSFL) and regular spikes at a fluence F \ 250 mJ/cm2 and 1,000 \ N B 10.000 shots. LSFL was observed with a spatial period close to the irradiation wavelength and an orientation perpendicular to the laser polarization, and HSFL with a spatial period of *120 nm and a parallel orientation. Lastly, the global relationship between the laser parameters (i.e. fluence and number of shots) and LIPSS formation was established in the form of a 2D map

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