Jacob Chapman Pui-Wai Ma Sergei Dudarev
Fundamental flaws in the Heisenberg Hamiltonian are highlighted in the context of its application to BCC Fe, including the particular issues arising when modelling lattice defects. Exchange integrals are evaluated using the magnetic force theorem. The bilinear exchange coupling constants are calculated for all the interacting pairs of atomic ma…
PublishedB Chapman R O Dendy S C Chapman K G McClements R Ochoukov
Observations have recently been made of ion cyclotron emission (ICE) that originates from the core plasma in the DIII-D and ASDEX-Upgrade tokamaks. In some of these cases, the ICE spectral peaks correspond to the local cyclotron harmonic frequencies of fusion-born ions close to the magnetic axis. This is in contrast to the hitherto usual spatial lo…
PreprintIan Chapman Nick Walkden
Fusion energy is an area of active development and innovation worldwide, with many design concepts exhibiting a range of technical challenges. A significant portion of technical challenges will be unique for a given design concept, however there are several overarching challenges that any design must address to some degree. These include: Tritiu…
Preprint PublishedR O Dendy B Chapman G S Yun S C Chapman K G McClements S G Thatipamula M H Kim A Zalzali
Intense suprathermal radiation, with spectral peaks at multiple harmonics of the deuteron cyclotron frequency, is detected from the outer midplane edge of KSTAR deuterium plasmas that are heated by tangential neutral beam injection (NBI) of 100keV deuterons. We identify how this deuterium ion cyclotron emission (ICE) is generated, and distinguish t…
Preprint PublishedR O Dendy B Chapman S C Chapman K G McClements G S Yun S G Thatipamula M H Kim
During ELM crashes in deuterium plasmas in the KSTAR tokamak, the emitted electromagnetic radiation includes features with sharp spectral structure in the frequency range up to ~900MHz. Cases where the spectral peaks below ~500MHz correspond to proton cyclotron harmonics at the outer midplane edge are explained (B Chapman et al., Nucl.…
Preprint PublishedB Chapman R O Dendy S C Chapman L Holland S W A Irvine and B C G Reman
Observations have recently been made of ion cyclotron emission (ICE) that originates from the core plasma in the DIII-D [1, 2] and ASDEX-Upgrade [3, 4] tokamaks. The ICE spectral peaks correspond to the local cyclotron harmonic frequencies of fusion-born ions close to the magnetic axis, in contrast to the hitherto usual spatial localisation of …
Preprint PublishedB C G Reman R O Dendy T Akiyama S C Chapman J W S Cook H Igami S Inagaki K Saito G S Yun
Ion cyclotron emission (ICE) is detected from all large toroidal magnetically con ned fusion (MCF) plasmas. It is a form of spontaneous suprathermal radiation, whose spectral peak frequencies correspond to sequential cyclotron harmonics of energetic ion species, evaluated at the emission location. We fi rst present an account of the worldwide exper…
Preprint PublishedB Chapman R O Dendy S C Chapman K G McClements G S Yun S G Thatipamula M H Kim
Intense bursts of suprathermal radiation, with spectral peaks at frequencies corresponding to the deuteron cyclotron frequency in the outer midplane edge region, are often detected from deuterium plasmas in the KSTAR tokamak that are heated by tangential neutral beam injection (NBI) of deuterons at 100 keV. Identifying the physical process by wh…
Preprint PublishedJames Harrison RJ Akers SY Allan JS Allcock JO Allen L Appel M Barnes N Ben Ayed W Boeglin C Bowman J Bradley P Browning P Bryant M Carr M Cecconello CD Challis S Chapman IT Chapman GJ Colyer S Conroy NJ Conway M Cox G Cunningham RO Dendy W Dorland BD Dudson L Easy SD Elmore T Farley X Feng AR Field A Fil GM Fishpool M Fitzgerald
Recent results from MAST address key physics issues for ITER operations and the design of future devices, by advancing our understanding of through analysis of high-resolution data and numerical modelling. Modelling of the interaction between filaments with BOUT++ indicates filaments separated by more than 5x their width move independently, and …
Preprint PublishedJ. Chapman Pui-Wai Ma S. L. Dudarev
Magnetic plasma confinement is a key element of fusion tokamak power plant design, yet changes in magnetic properties of alloys and steels occurring under neutron irradiation are often overlooked. We perform a quantitative study exploring how irradiation-induced precipitation affects magnetic properties of Fe-Cr alloys. Magnetic properties are simu…
Preprint Published