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Roedig M.,Julich Research Center | Barabash V.,ITER Organization | Eaton R.,ITER Organization | Hirai T.,ITER Organization | And 5 more authors.
Fusion Science and Technology | Year: 2012

In order to qualify new beryllium grades for ITER, several Russian and Chinese materials were tested in the electron beam facility JUDITH-I and compared to the reference material S65C. In a former campaign, samples from these materials were loaded in thermal shock experiments with single shots and multiple shots. The present work is an extension of this work to other loading scenarios. Four actively cooled mock-ups were produced in Russia and in China (two by each party). These mock-ups consisted of a water-cooled CuCrZr body with four tiles from different beryllium grades. Both parties used their own joining techniques, but each of the mock-ups also contained beryllium tiles from the other party, as well as from S65C. Each tile was loaded by the following scenarios on different surface areas: simulation of vertical displacement events (VDEs) at 40 MJ/m 2, 1 shot, heated area a = 10×10 mm 2, 50-ms ramp-up, 165-ms steady state disruption simulation at 3 MJ/m 2, 1 shot, heated area a = 5 × 5 mm 2, △t = 5 ms repetitive test with 1000 shots at 80 MW/m 2 (2 MJ/ m 2), a = 10× 10 mm 2, △t = 25 ms. This loading condition is similar to one that was proposed by Sandia National Laboratory for the comparison of different beryllium grades. Finally, one mock-up by each party underwent a thermal fatigue test with 1000 cycles at 2 MW/m 2, 15 s heating, and 15 s cooling (heated area: whole sample surface). Heavy melting was observed in the area of the VDE loading, but no detachment of any of the tiles was found. Following the high-heat-flux experiments in the electron beam facility, post-mortem examinations were performed by optical photography and scanning electron microscopy on the surfaces as well as by metallography. From these analyses, no fundamental differences were found for the damage in the different beryllium grades.

Kovalenko D.V.,SRC RF TRINITI | Klimov N.S.,SRC RF TRINITI | Podkovyrov V.L.,SRC RF TRINITI | Muzichenko A.D.,SRC RF TRINITI | And 4 more authors.
Physica Scripta T | Year: 2011

This paper presents preliminary results on the erosion of beryllium under hydrogen plasma flow. Two samples made of two types of beryllium, TGP-56PS and S-65C, were exposed to plasma heat loads up to 1 MJ m -2 and a pulse duration of 0.5 ms at the QSPA-Be facility in Bochvar Institute, Russia. The melting threshold for both beryllium types was experimentally determined to be 0.5 MJ m -2. The dependence of the specific mass loss and erosion rate on pulse number for both beryllium types was measured. The possibility of generating radiation fluxes with parameters corresponding to mitigated ITER disruptions by means of plasma flow shock braking on a solid bar is shown. © 2011 The Royal Swedish Academy of Sciences.

Roedig M.,Julich Research Center | Kupriyanov I.,Bochvar Institute | Linke J.,Julich Research Center | Liu X.,Southwestern Institute of Physics | Wang Z.,CNMC Orient Group Co.
Journal of Nuclear Materials | Year: 2011

In order to simulate transient events on beryllium, thermal shock experiments have been carried out in the electron beam facility JUDITH. Different grades of Chinese and Russian beryllium have been loaded in comparison to the ITER reference grade S65C. The pulse length was 5 ms, and energy densities covered the range from 1.2 to 5 MJ/m2. All tests have been performed at room temperature. In a second series of tests, the influence ELM-like conditions has been investigated. Multiple shot experiments with up to 10,000 cycles on beryllium S65C were carried out at energy densities below the ones for the onset of crack formation in single shot experiments. Most loading parameters were similar to the single shot tests, but in addition the experiments were carried out on hot beryllium surfaces of 250 °C. Post mortem examinations of the samples were carried out by optical microscopy, SEM, metallography and other diagnostic methods. © 2010 Elsevier B.V. All rights reserved.

Klimov N.S.,National Research Nuclear University MEPhI | Putrik A.B.,SRC RF TRINITI | Linke J.,Julich Research Center | Pitts R.A.,Karlsruhe Institute of Technology | And 15 more authors.
Journal of Nuclear Materials | Year: 2015

Abstract PFMs (Plasma-facing materials: ITER grade stainless steel, beryllium, and ferritic-martensitic steels) as well as deposited erosion products of PFCs (Be-like, tungsten, and carbon based) were tested in QSPA under photonic heat loads relevant to those expected from photon radiation during disruptions mitigated by massive gas injection in ITER. Repeated pulses slightly above the melting threshold on the bulk materials eventually lead to a regular, "corrugated" surface, with hills and valleys spaced by 0.2-2 mm. The results indicate that hill growth (growth rate of ∼1 μm per pulse) and sample thinning in the valleys is a result of melt-layer redistribution. The measurements on the 316L(N)-IG indicate that the amount of tritium absorbed by the sample from the gas phase significantly increases with pulse number as well as the modified layer thickness. Repeated pulses significantly below the melting threshold on the deposited erosion products lead to a decrease of hydrogen isotopes trapped during the deposition of the eroded material. © 2014 Published by Elsevier B.V.

Keilin V.E.,RAS Research Center Kurchatov Institute | Kovalev I.A.,RAS Research Center Kurchatov Institute | Kruglov S.L.,National Research Nuclear University | Sherbakov V.I.,RAS Research Center Kurchatov Institute | And 4 more authors.
Superconductor Science and Technology | Year: 2015

In this paper we report our recent research on thermal stabilization of low-temperature superconducting magnets by means of large heat capacity substances (LHCS). Two samples (lengths ∼100 m) of NbTi composite wires with additional internal filaments made from intermetallic compound PrB6 (5.9-7.3 vol.%) were produced and tested. The design of the wires was similar to that of the conventional MRI sc wires, except for their smaller diameter (0.835 mm instead of 1.345 mm). Our final goal was the investigation of the possibility to minimize (or even eliminate completely) the necessity of MRI magnets training before their commissioning. The comparative stability measurements showed a twofold increase of the minimum quench energies (MQEs) of the doped wires against short heat disturbances. The magnetic field corresponding to the first flux jump increased by 50%. In MQE tests, the PrB6 heat capacity was fully utilized over the course of a 1 ms heat pulse. In the thermomagnetic stability measurements, the efficiency of LHCS doping was about 75% due to the fast evolution of the flux jumps. © 2015 IOP Publishing Ltd.

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