TY - JOUR
T1 - Studies of Be migration in the JET tokamak using AMS with 10Be marker
AU - Bykov, I.
AU - Bergsåker, H.
AU - Possnert, G.
AU - Zhou, Y.
AU - Heinola, K.
AU - Pettersson, J.
AU - Conroy, S.
AU - Likonen, Jari
AU - Petersson, P.
AU - Widdowson, A.
PY - 2016/3/15
Y1 - 2016/3/15
N2 - The JET tokamak is operated with beryllium limiter tiles in the main chamber and tungsten coated carbon fiber composite tiles and solid W tiles in the divertor. One important issue is how wall materials are migrating during plasma operation. To study beryllium redistribution in the main chamber and in the divertor, a 10Be enriched limiter tile was installed prior to plasma operations in 2011-2012. Methods to take surface samples have been developed, an abrasive method for bulk Be tiles in the main chamber, which permits reuse of the tiles, and leaching with hot HCl to remove all Be deposited at W coated surfaces in the divertor. Quantitative analysis of the total amount of Be in cm2 sized samples was made with inductively coupled plasma atomic emission spectroscopy (ICP-AES). The 10Be/9Be ratio in the samples was measured with accelerator mass spectrometry (AMS). The experimental setup and methods are described in detail, including sample preparation, measures to eliminate contributions in AMS from the 10B isobar, possible activation due to plasma generated neutrons and effects of diffusive isotope mixing. For the first time marker concentrations are measured in the divertor deposits. They are in the range 0.4-1.2% of the source concentration, with moderate poloidal variation.
AB - The JET tokamak is operated with beryllium limiter tiles in the main chamber and tungsten coated carbon fiber composite tiles and solid W tiles in the divertor. One important issue is how wall materials are migrating during plasma operation. To study beryllium redistribution in the main chamber and in the divertor, a 10Be enriched limiter tile was installed prior to plasma operations in 2011-2012. Methods to take surface samples have been developed, an abrasive method for bulk Be tiles in the main chamber, which permits reuse of the tiles, and leaching with hot HCl to remove all Be deposited at W coated surfaces in the divertor. Quantitative analysis of the total amount of Be in cm2 sized samples was made with inductively coupled plasma atomic emission spectroscopy (ICP-AES). The 10Be/9Be ratio in the samples was measured with accelerator mass spectrometry (AMS). The experimental setup and methods are described in detail, including sample preparation, measures to eliminate contributions in AMS from the 10B isobar, possible activation due to plasma generated neutrons and effects of diffusive isotope mixing. For the first time marker concentrations are measured in the divertor deposits. They are in the range 0.4-1.2% of the source concentration, with moderate poloidal variation.
KW - Accelerator mass spectrometry (AMS)
KW - Beryllium
KW - ITER-like Wall
KW - Materials migration
KW - Nuclear fusion
UR - http://www.scopus.com/inward/record.url?scp=84960348188&partnerID=8YFLogxK
U2 - 10.1016/j.nimb.2015.12.007
DO - 10.1016/j.nimb.2015.12.007
M3 - Article
AN - SCOPUS:84960348188
SN - 0168-583X
VL - 371
SP - 370
EP - 375
JO - Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms
JF - Nuclear Instruments and Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms
ER -