Interaction of high temperature deuterium plasma streams and fast ion beams with stainless steels in dense plasma focus device

Abstract

Interaction of deuterium plasma of streams and shock-waves (velocities up to 5 × 10 7 cm s −1 ) and fast ion beams (50-150 keV) generated in a dense plasma focus (DPF) device with low-activated austenitic steel, 25Cr12Mn20W, and ferritic steel, 10Cr9W, specimens positioned in the cathode part of DPF chamber has been investigated. If the power flux density of both types of irradiation is about q = 10 5 -10 7 W cm −2 , then ion implantation into a surface layer of the materials was observed. An increase of this parameter till q = 10 7 -10 8 W cm −2 results in the so-called 'detachment' effect (screening of the specimen surface by a cold plasma cloud). When the power flux density is increased up to q = 10 9 -10 10 W cm −2 , the evaporated plasma cloud becomes of the same temperature as the plasma of the shock-wave, and melting and evaporation of material from the specimen surface appears to be very strong, thus the so-called 'broken-implantation' takes place.

In-line and following-up tests of perspective fusion-reactor materials in plasma focus devices

“…And an extrapolation of the spectroscopic data to the surface and to the impact moment (verified by the data on estimations and numerical simulation for the SP made in [7]) gives us for the pressure of the near-surface plasma a value of about 3 orders of magnitude higher, i.e. circa 109 Pa (~ 10 kbar).…”

“…pinching time, current abruption phenomena, the overall energy balance of the discharge, magneto-hydrodynamic motion of the plasma-current sheath, and the production of a cumulative plasma jet, efficiency of the beams generation, etc. [7,8,12,14]. Additionally, it was found by means of optical diagnostics (see Fig.…”

“…For the determined f values, the estimated q value should be within the range of (1011-1013) W/m 2. Such high q values must produce strong damages: the melting of a surface layer under the irradiation, its sublimation, crack formation, and brittle destruction [1][2][3][4]7]. However, no noticeable melting was observed in our experiments.…”

“…The measured energy spectrum of recoil deuterons was converted into a scattering profile by means of the Rutherford Universal Manipulation Program (RUMP) [7,15]. In order to get the absolute value of the deuteron concentration, use was made of a Fig.…”

“…The samples of the investigated materials might be irradiated within highcurrent short-pulsed accelerators, as the Dense Plasma Focus (DPF) devices, which generate intense plasma streams (PS) and fast ions beams (FIB) of power flux density P considerably higher than that expected within the real MPC reactors, and even higher than in the ICF ones (since they can reach as rauch as almost P ~ 1014Wm -2 [7,8]). In this case one can anticipate a challenge of a much shorter material testing cycle.…”