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Surface analysis

The Surface Analysis Laboratory at IFP is mainly devoted to the study of plasma-wall interaction within nuclear reactors.

In this area, the most common phenomena are erosion, re-deposition, morphological variation, and variation in the chemical state of the surface of the first wall.

Through XPS and SIMS analysis it is possible to investigate the surface and the bulk of the elements on the surface and their chemical status (oxidation, hydration, boronization, lithography, etc...

XPS
Impianto per la spettroscopia di foto-elettroni. Caratteristiche tecniche: dual anode (Al, Mg), risoluzione 0.8 ev, range di temperature da 100 K to 1300 K.Diagnostiche installate: AES, EELS, LEIS (A, Ne, He), UPS, LEED.<br />

 

SIMS
Impianto per la spettrometira di massa di ioni secondari. Caratteristiche tecniche: AMU 1-300, 1-50 AMU ad alta sensibilità, risoluzione 1 AMU. Diagnostiche installate: Secondary Ion Mass Spettrometry (SIMS) e spettroscopia per desorbimento termico (TDS) fino a T=1300 K.<br />

The laboratory also provides support activities to other sample analysis laboratories, such as thin film deposited to provide surface functionality or nanostructured surfaces.

In the following figures, sample analyses are performed using XPS and SIMS devices.

XPS Spectra
Spettri ad alta risoluzione ottenuti da misure con XPS su un campione di mattonella della parete del reattore RFX.
SIMS_Profiles
SIMS depth profiles of C, O, BO, B, BH and H ions of a tile of RFX Reactor.
Recent publications:
  • F. Ghezzi et Al. “XPS, SIMS and FTIR-ATR characterization of boronized graphite from the thermonuclear plasma device RFX-mod”, Applied Surface Science 354 (2015) 408-419.
  • E. Vassallo, F. Ghezzi et al., “Characterization of Poly(3-Methylthiophene)-like Films Produced by Plasma Polymerization”, Plasma Processes and Polymers” 2007, 4, S801–S805.
  • R. Caniello F. Ghezzi et al., “Erosion yield and W surface enrichment of Fe-W model system exposed to low flux deuterium plasma in the linear device GyM“, Nuclear Material and Energy 10 (2017) 9-16.
  • A. Hakkola, F. Ghezzi et al., “Plasma-wall interaction studies in the full W ASDEX upgrade during helium plasma discharges”, Nuclear Fusion 57 (2017) 066015.

Spectroscopy

Another very useful surface analysis technique is the low power ion reflection spectroscopy (LEIS). It can be presently considered the most sensitive surface analysis technique as it is sensitive to the surface monolayer. Therefore, for example, it is used in catalysis studies, investigations of any unintended superficial deposition induced by superficial erosion or enrichment as in the case below.

LEIS_Spectra
LEIS spectra on two different FeW layers. The spectra were acquired using 1 keV Ne with 45 deg incidence angle and 90 deg scattering angle.

A highly used technique for the study of gas trapping in atomic vacancies and induced by irradiation in samples exposed to fusion plasmas is the programmed desorption spectroscopy (TDS). The example illustrated in the following figure shows the case of He trapped in W-porous structures formed on the surface of a W sample due to He-plasma high flow exposures. Helium desorption was performed with the TDS implemented in the SIMS laboratory at IFP.

TDS Data
Misura del rilascio di elio (He) da un campione di tungsteno (W), ottenuta tramite diagnostica TDS.

In the laboratory there is also a small PCVD plant dedicated to the study of diamonds growth and carbon-oriented structures for the development of neutron sensors.

Diamond structure 1
Diamond structures deposition at 1020 °C and 200 Torr.
Diamond structures 2
Diamond structures deposition at 1020 °C and 200 Torr (detail).
HOPG vs CVD
Misura della perdita di energia per HOPG e CVD. L'energia del fascio di e;ettroni primari è pari a 2070.5 eV.

Recent publications:

  • F.Ghezzi, et al., “Carbon Structures Grown by Direct Current Microplasma: Diamonds, Single-Wall Nanotubes, and Graphene”, Journal of Physical Chemistry. C, 2014, 118 (42), pp 24714–24722.

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