Implantation of Deuterium and Helium Ions into a Tungsten-Coated Composite Structures

Abstract

The capture, retention, and thermal desorption of deuterium and helium ions with medium energies implanted into tungsten-coated multilayer functional structures and the formation of corresponding radiation-induced damages in the crystal lattice of the tungsten coatings of those structures have been studied making use of the thermal desorption spectroscopy and electron microscopy methods. The behavior of deuterium and helium in the examined materials and its dependence on the post-implantation heating temperature, the dose of irradiation with D+ and He+ ions, and the irradiation condition – separate (making use of ions of only one kind) or sequential (making use of ions of both kinds) – are analyzed. A classification of radiation-induced defects and mechanisms of their annealing are proposed.

Investigation of the Processes of Retention and Release of Implanted Deuterium and Helium Ions for Tungsten and Tantalum Coatings

“…For hydrogen in bulk tungsten at 500 K, the recombination rate coefficients 10 -29 -10 -31 m 4 /s have been determined by many researchers. In the described below works [10,14,27,28,36,37,[39][40][41][42][43][44][45][46][47][48][49][50][51] much attention has been paid to the processes of retention and release of hydrogen isotopes in tungsten coatings proposed as protect for components facing the plasma (the first wall, divertor, antenna mirrors).…”

“…The authors of this work studied tungsten and tantalum coatings deposited by the MS method on stainless steel. The deposition technique was described in details in [35][36][37]. Coatings were prepared by sputtering W or Ta targets in Ar atmosphere at the pressure of 1.0 Pa.…”

“…This work authors Bobkov at al. studied tungsten coatings of different thicknesses deposited on stainless steel substrates [36,37,[45][46][47][48][49]. The stainless steel substrate 0.8 mm thick had the following composition (at %): 20 Cr, 70 Fe, 8.5 Ni, and 1.5 Ti.…”

“…The copper sublayer reduced internal compressive stresses. In the listed works [36,37,[45][46][47][48][49], the authors studied the types of formed radiation defects, their relationship with defects in the tungsten crystal lattice, mechanisms of their migration and annealing, including release of implanted deuterium from the sample into vacuum. Spectra of deuterium thermal desorption were analyzed and temperature intervals for the release of D2 from the coatings into vacuum were cleared.…”

“…Changes in the microstructure of the W coatings and the morphology of their surface in the result of ion irradiation and subsequent heating were observed. To clarify the radiation stability of the system "W-film-implanted deuterium", we studied the influence of coating thickness [45,46,48], the type of composite system (determined by the multilayer nature of the substrate) [45,46], fluences of D + ions irradiation [46,47,49] and sample temperature during bombardment [36,37] on the above parameters, characteristics, physical and structural properties of the coatings.…”