Beryllium Samples under Tritium Irradiation
Experimental Tests of Plasma-Facing Materials Designed for Thermonuclear Fusion Reactors (Be, W, CFC) under Hot Deuterium-Tritium Plasma and Fast Ion Beam Irradiation
Tech Area / Field
- CHE-DAC/Destruction and Conversion/Chemistry
- ENV-EHS/Environmental Health and Safety/Environment
- FUS-ICS/Inertial Confinement Systems/Fusion
- FUS-MCS/Magnetic Confinement Systems/Fusion
- MAT-ALL/High Performance Metals and Alloys/Materials
- MAT-SYN/Materials Synthesis and Processing/Materials
- PHY-SSP/Solid State Physics/Physics
3 Approved without Funding
All-Russian Research Institute of Automatics, Russia, Moscow
- Baykov Metallurgy and Materials Institute, Russia, Moscow
- Sandia National Laboratories, USA, NM, Albuquerque\nNational Institute for Lasers, Plasma and Radiation Physics, Romania, Magurele\nInstitute of Plasma Physics & Laser Microfusion, Poland, Warsaw
Project summaryThe main aim of the Project is to provide experimental tests of the complete number of plasma facing materials adopted for use in contemporary main-stream fusion facilities (FF) with magnetic plasma confinement (MPC) like JET (Culham, UK) and Iter (Cadarache, France) including poison beryllium, as well as tungsten and carbon-fiber composites, plus stainless steels and ceramics. The tests will be provided by irradiation of their specimens with hot (~1 keV) plasma and streams of fast (~100 keV) radioactive tritons, deuterons, and electrons in conditions that are very close to those expected at the chamber wall of the above fusion facilities. Side by side with the experimental tests theoretical explanation and forecast of behavior of the contemporary fusion reactor materials in real operational regimes of FF will be provided.
The methodology of the Project is comprised by 3 factors:
1) Application of the compact sealed chambers of the Dense Plasma Focus (DPF) devices for the tests of the complete number of “plasma-facing materials”, including beryllium, by directed streams of deuterium-tritium (DT) hot plasma and fast ions. These features make the tests relatively cheap, ecologically acceptable and highly representative
2) Development the on-line diagnostic methods of processes of plasma/beams interaction with the samples, having high temporal and spatial resolution, which are necessary to monitor the above procedure in dissimilar conditions
3) Application of contemporary analytical methods for investigation of the irradiated toxic and radioactive samples.
DPF produces relatively short pulses of ion/electron beams and plasma streams (from 100 till 1000 ns). However there are three factors, which make it very productive for the radiation damage tests of materials of FF with MPC:
- Almost all parameters (except pulse durations) of plasma streams, ion/electron beams generated by DPF (plasma elemental contents, its temperature and density, energy of fast ions) as well as X-Rays and neutrons energies are the same as realized in JET or expected in Iter near the chamber walls.
- Primary plasma and beams of fast ions and electrons irradiate a target in DPF during a shorter interval of time (from 100 ns till few microseconds) if compared with transient events taking place in a tokamak (e.g. ELMs) indeed. However secondary plasma produced by these streams at the target’s surface loses its density and temperature during ~ 100 µs. This time interval ensuring heat loads is comparable with the duration of the transient events in tokamaks.
- Discussed in a number of papers a so-called damage factor: F ~ qt 1/2 (where q is power flux density and t – pulse duration of radiation) gave another opportunity: because DPF devices can produce power flux density q on the specimen’s surface at least 2-4 orders of magnitude higher than it is realized in the main-stream FFs at the surfaces of plasma-facing components, the same value of F may be reached at pulse duration of radiation t 4-8 orders of magnitude shorter.
At the same time Dense Plasma Focus device may ideally simulate conditions realized on the first wall in the frontier fusion devices with inertial plasma confinement (IPC) like NIF (Lawrence Livermore National Laboratory, USA).
Being invented in the 50’s DPF is the most well-diagnosed plasma device at present time. To have data on parameters of the fast electron and ion beams, hot plasma streams, soft and hard X-Ray radiation, and neutrons (velocity, spectrum, angular distribution, absolute yields, fluence, power flux density, etc.) the Project’s teams use a number of diagnostics, having about 1-ns temporal, few micrometers spatial, high spectral and angular resolution. The same is true for secondary plasma produced at the surface of the specimens under tests and for the interaction processes.
VNIIA team has a very good and long (more than 20 years) experience in operation of DPF with DT mixture as a working gas, and it was already supported by two ISTC Projects. On the contrary to those Projects in the frame of current Proposal the DP foci will now be prepared by VNIIA team for the first time for irradiation of specimens by plasma and fast ion beams inside the DPF chamber in the course of radiation material science experiments, what excludes an ingress of radio-nuclides into environment. IMET team has a very fruitful experience in radiation material science in general and in fusion material tests with a help of DPF in particular (e.g. in the framework of the successfully completed EU International Project “Copernicus” and the International Atomic Energy Agency Co-ordinated Research Programme “Dense Magnetized Plasma”). IMET will participate in the Project’s activity by analytical investigations of specimens after their irradiation, by modeling experiments with use DPF devices, and in development of numerical simulation of the temperature field evolution within the surface layer of materials at their irradiation for use the results in interpretation of the radiation damages and in forecasts of the radiation material tolerance.
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