UKAEA Journals

Showing 1 - 10 of 107 Journals Results
2021
UKAEA-CCFE-PR(21)09
"Density dependence of ion cyclotron emission from deuterium plasmas in the Large Helical Device"

B. C. G. Reman R. O. Dendy T. Akiyama S. C. Chapman J. W. S. Cook H. Igami S. Inagaki K. Saito M.H. Kim S.G. Thatipamula G. S. Yun

Ion cyclotron emission (ICE) driven by perpendicular neutral beam-injected (NBI) deuterons, together with the distinctive ICE driven by tangential NBI, have been observed from heliotron-stellarator plasmas in the Large Helical Device (LHD). Radio frequency radiation in the lower hybrid range has also been observed, with frequency dependent on plasm…

Preprint
2020
UKAEA-CCFE-PR(21)48
"Interpretation of transient bursts of ion cyclotron emission from fusion-born protons in deuterium plasmas in the Large Helical Device"

B. C. G. Reman R. O. Dendy T. Akiyama M. Salewski S.C. Chapman J. W. S. Cook H. Igami S. Inagaki K. Saito R.Seki G. S. Yun

During bursty MHD events, transient ion cyclotron emission (ICE) is observed from deuterium plasmas in the Large Helical Device (LHD) heliotron-stellarator. Unusually, the frequencies of the successive ICE spectral peaks are not close to integer multiples of the local cyclotron frequency of an energetic ion population in the likely emitting region.…

Preprint
2020
UKAEA-CCFE-PR(20)94
"An overview of shared technical challenges for magnetic and inertial fusion power plant development"

Ian 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 Purchase
2019
UKAEA-CCFE-PR(19)64
"Theory and simulation of ion cyclotron emission from energetic ion populations with a spherical shell distribution in velocity-space"

B 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 Published
2019
UKAEA-CCFE-PR(19)24
"Interpreting observations of ion cyclotron emission from Large Helical Device plasmas with beam-injected ion populations"

B 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 conned 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 first present an account of the worldwide exper…

Preprint Published
2019
UKAEA-CCFE-PR(19)08
"Interpretation of suprathermal emission at deuteron cyclotron harmonics from deuterium plasmas heated by neutral beam injection in the KSTAR tokamak"

B 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 Published
2018
UKAEA-CCFE-PR(18)83
"The Dynamics of Magnetism in Fe-Cr Alloys with Cr Precipitation"

J. 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
2018
UKAEA-CCFE-PR(18)76
"UKAEA capabilities to address the challenges on the path to delivering fusion power"

Ian Chapman William Morris

Fusion power could be one of very few sustainable options to replace fossil fuels as the world’s primary energy source. Fusion offers the potential of predictable, safe power with no carbon emissions, and fuel sources lasting for millions of years. However, it is notoriously difficult to achieve in a controlled, steady-state fashion. The most pro…

Preprint Published
2018
UKAEA-CCFE-PR(19)03
"The role of particle, energy and momentum losses in 1D simulations of divertor detachment"

B D Dudson J Allen T Body B Chapman C Lau L Townley D Moulton J Harrison B Lipschultz

A new 1D divertor plasma code, SD1D, has been used to examine the role of recombination, radiation, and momentum exchange in detachment. Neither momentum or power losses by themselves are found to be sufficient to produce target ion flux rollover in detachment; radiative power losses are required to a) limit and reduce the ionization source and …

Preprint Published
2018
UKAEA-CCFE-PR(18)14
"Observations and modelling of ion cyclotron emission observed in JET plasmas using a sub-harmonic arc detection system during ion cyclotron resonance heating"

K. G. McClements A. Brisset B. Chapman S. C. Chapman R. O. Dendy P. Jacquet V. G. Kiptily M. Mantsinen B. C. G. Reman JET Contributors

Measurements are reported of electromagnetic emission close to the cyclotron frequency of energetic ions in JET plasmas heated by waves in the ion cylotron range of frequencies (ICRF). Hydrogen was the majority ion species in all of these plasmas. The measurements were obtained using a sub-harmonic arc detection (SHAD) system in the transmission li…

Preprint Published