E. Rachlew | KTH Royal Institute of Technology (original) (raw)
Papers by E. Rachlew
Nuclear Materials and Energy, 2019
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spectroscopic method to determine changes in the electron
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ABSTRACT. Injection of Lower Hybrid Heating and Current Drive (LHCD) into the current ramp-up pha... more ABSTRACT. Injection of Lower Hybrid Heating and Current Drive (LHCD) into the current ramp-up phase of JET discharges can produce extremely reversed q-profiles characterized by a core region of near zero current density (within Motional Stark Effect diagnostic measurement errors). Non-inductive, off-axis co-current drive induces a back electromotive force inside the non-inductive current radius that drives a negative current in the plasma core. The core current density does not go negative, although current diffusion calculations indicate that there is sufficient LHCD to cause this. The clamping of the core current density near zero is consistent with n=0 reconnection events redistributing the core current soon after it goes negative. This is seen in reduced MHD simulations and in nonlinear resistive MHD simulations which predict that these
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Abstract. Plasma equilibria before and after ELMs in JET are investigated. ELMs could be associat... more Abstract. Plasma equilibria before and after ELMs in JET are investigated. ELMs could be associated with fragile equilibria and separatrix instabilities: previously closed field lines would open up, releasing plasma current and leading to the formation of a new, smaller separatrix. This model could explain experimental observations of sudden jumps and shifts in strike point positions. Novel instability mechanisms are discussed to explain the large transient jumps observed in the strike point position: positive X-point instability, due to positive toroidal current density at the X-point and diamagnetic instability, due to negative inboard toroidal current density. 1. Theoretical background: plasma equilibrium before the ELM Plasma force balance in a magnetic confinement device with closed field lines is given by the equation: j B × =∇pGG (1) where j is the total current density, B the magnetic field and p the pressure. In tokamak equilibrium, the pressure is usually considered as a m...
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Journal of Photochemistry and Photobiology A: Chemistry, 2018
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Plasma Physics and Controlled Fusion, 2016
Three dimensionless scans in the normalized Larmor radius rho*, normalized collisionality nu* and... more Three dimensionless scans in the normalized Larmor radius rho*, normalized collisionality nu* and normalized plasma pressure beta have been performed in JET with the ITER-like wall (JET-ILW). The n ...
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Journal of Physics: Conference Series, 2015
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Physical Review Letters, 1991
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Nuclear Fusion, 2009
Since the last IAEA conference, the scientific programme of JET has focused on the qualification ... more Since the last IAEA conference, the scientific programme of JET has focused on the qualification of the integrated operating scenarios for ITER and on physics issues essential for the consolidation of design choices and the efficient exploitation of ITER. Particular attention has been given to the characterization of the edge plasma, pedestal energy and edge localized modes (ELMs), and their
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Chemical Physics Letters, 1997
ABSTRACT The photoion excitation spectrum of NO has been measured in the 9.26–13.8 eV region usin... more ABSTRACT The photoion excitation spectrum of NO has been measured in the 9.26–13.8 eV region using synchroton light and the isotopic targets 14N16O, 15N16O and 15N18O. The resulting complex spectra have been interpreted using ab initio results based on many-body theory. The ab initio predictions suggest that the structure follows from autoionizations of four repulsive valence states of 2Σ symmetry and interactions between an attractive 2δ valence state and Rydberg series converging to the NO+ ground state.
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Journal of Physics B: Atomic, Molecular and Optical Physics, 2007
Page 1. Lyman and Balmer emission following core excitations in methane and ammonia molecules Thi... more Page 1. Lyman and Balmer emission following core excitations in methane and ammonia molecules This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2007 J. Phys. B: At. Mol. Opt. Phys. 40 1489 ...
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Nuclear Fusion, 2017
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spectroscopic method to determine changes in the electron
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We report the identification of a localized current structure inside the JET plasma. It is a fiel... more We report the identification of a localized current structure inside the JET plasma. It is a field aligned closed helical ribbon, carrying current in the same direction as the background current profile (co-current), rotating toroidally with the ion velocity (co-rotating). It appears to be located at an n=1 rational surface at a flat spot in the plasma pressure profile, at the top of the pedestal, and not in the gradient region. The current structure appears spontaneously in low density, high pedestal temperature, high rotation plasmas, and can last up to 1. s, a time comparable to a local resistive time. It considerably delays the appearance of the first ELM, and regulates transport across the separatrix.
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Journal of Physics C: Solid State Physics, 1975
The Te L1 and L3 X-ray absorption spectra for some GeTe compounds in amorphous and crystalline fo... more The Te L1 and L3 X-ray absorption spectra for some GeTe compounds in amorphous and crystalline form are presented. No shifts of the Te core levels 2s and 2p3/2 were observed between the amorphous and crystalline phases or between the element and the compounds. The L3 but not the L1 spectra showed changes in structure about 5-10 eV above the Fermi level when amorphous GeTe crystallized. This is attributed to states about 6 eV above EF and it is concluded that these largely d-like states are more affected by the order-disorder transformation than the lower sp bands.
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Ambio, 2016
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Physical Review A, 2015
Fragmentation of gas-phase chloro-and bromoacetic acid samples, particularly its dependency on th... more Fragmentation of gas-phase chloro-and bromoacetic acid samples, particularly its dependency on the atomic site of the initial core ionization, was studied in photoelectron-photoion-photoion coincidence (PEPIPICO) measurements. The fragmentation was investigated after ionizing carbon 1s and bromine 3d or chlorine 2p core orbitals. It was observed that the samples had many similar fragmentation pathways and that their relative weights depended strongly on the initial ionization site. Additional Auger PEPIPICO measurements revealed a clear dependence of fragment pair intensities on the kinetic energy of the emitted Auger electrons. The modeled and measured Auger electron spectra indicated that the average internal energy of the molecule was larger following the carbon 1s core-hole decay than after the decay of the halogen core hole. This difference in the internal energies was found to be the source of the site-dependent photofragmentation behavior.
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Nuclear Materials and Energy, 2019
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spectroscopic method to determine changes in the electron
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ABSTRACT. Injection of Lower Hybrid Heating and Current Drive (LHCD) into the current ramp-up pha... more ABSTRACT. Injection of Lower Hybrid Heating and Current Drive (LHCD) into the current ramp-up phase of JET discharges can produce extremely reversed q-profiles characterized by a core region of near zero current density (within Motional Stark Effect diagnostic measurement errors). Non-inductive, off-axis co-current drive induces a back electromotive force inside the non-inductive current radius that drives a negative current in the plasma core. The core current density does not go negative, although current diffusion calculations indicate that there is sufficient LHCD to cause this. The clamping of the core current density near zero is consistent with n=0 reconnection events redistributing the core current soon after it goes negative. This is seen in reduced MHD simulations and in nonlinear resistive MHD simulations which predict that these
Bookmarks Related papers MentionsView impact
Abstract. Plasma equilibria before and after ELMs in JET are investigated. ELMs could be associat... more Abstract. Plasma equilibria before and after ELMs in JET are investigated. ELMs could be associated with fragile equilibria and separatrix instabilities: previously closed field lines would open up, releasing plasma current and leading to the formation of a new, smaller separatrix. This model could explain experimental observations of sudden jumps and shifts in strike point positions. Novel instability mechanisms are discussed to explain the large transient jumps observed in the strike point position: positive X-point instability, due to positive toroidal current density at the X-point and diamagnetic instability, due to negative inboard toroidal current density. 1. Theoretical background: plasma equilibrium before the ELM Plasma force balance in a magnetic confinement device with closed field lines is given by the equation: j B × =∇pGG (1) where j is the total current density, B the magnetic field and p the pressure. In tokamak equilibrium, the pressure is usually considered as a m...
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Journal of Photochemistry and Photobiology A: Chemistry, 2018
Bookmarks Related papers MentionsView impact
Plasma Physics and Controlled Fusion, 2016
Three dimensionless scans in the normalized Larmor radius rho*, normalized collisionality nu* and... more Three dimensionless scans in the normalized Larmor radius rho*, normalized collisionality nu* and normalized plasma pressure beta have been performed in JET with the ITER-like wall (JET-ILW). The n ...
Bookmarks Related papers MentionsView impact
Journal of Physics: Conference Series, 2015
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Physical Review Letters, 1991
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Nuclear Fusion, 2009
Since the last IAEA conference, the scientific programme of JET has focused on the qualification ... more Since the last IAEA conference, the scientific programme of JET has focused on the qualification of the integrated operating scenarios for ITER and on physics issues essential for the consolidation of design choices and the efficient exploitation of ITER. Particular attention has been given to the characterization of the edge plasma, pedestal energy and edge localized modes (ELMs), and their
Bookmarks Related papers MentionsView impact
Chemical Physics Letters, 1997
ABSTRACT The photoion excitation spectrum of NO has been measured in the 9.26–13.8 eV region usin... more ABSTRACT The photoion excitation spectrum of NO has been measured in the 9.26–13.8 eV region using synchroton light and the isotopic targets 14N16O, 15N16O and 15N18O. The resulting complex spectra have been interpreted using ab initio results based on many-body theory. The ab initio predictions suggest that the structure follows from autoionizations of four repulsive valence states of 2Σ symmetry and interactions between an attractive 2δ valence state and Rydberg series converging to the NO+ ground state.
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Journal of Physics B: Atomic, Molecular and Optical Physics, 2007
Page 1. Lyman and Balmer emission following core excitations in methane and ammonia molecules Thi... more Page 1. Lyman and Balmer emission following core excitations in methane and ammonia molecules This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2007 J. Phys. B: At. Mol. Opt. Phys. 40 1489 ...
Bookmarks Related papers MentionsView impact
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Nuclear Fusion, 2017
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spectroscopic method to determine changes in the electron
Bookmarks Related papers MentionsView impact
We report the identification of a localized current structure inside the JET plasma. It is a fiel... more We report the identification of a localized current structure inside the JET plasma. It is a field aligned closed helical ribbon, carrying current in the same direction as the background current profile (co-current), rotating toroidally with the ion velocity (co-rotating). It appears to be located at an n=1 rational surface at a flat spot in the plasma pressure profile, at the top of the pedestal, and not in the gradient region. The current structure appears spontaneously in low density, high pedestal temperature, high rotation plasmas, and can last up to 1. s, a time comparable to a local resistive time. It considerably delays the appearance of the first ELM, and regulates transport across the separatrix.
Bookmarks Related papers MentionsView impact
Journal of Physics C: Solid State Physics, 1975
The Te L1 and L3 X-ray absorption spectra for some GeTe compounds in amorphous and crystalline fo... more The Te L1 and L3 X-ray absorption spectra for some GeTe compounds in amorphous and crystalline form are presented. No shifts of the Te core levels 2s and 2p3/2 were observed between the amorphous and crystalline phases or between the element and the compounds. The L3 but not the L1 spectra showed changes in structure about 5-10 eV above the Fermi level when amorphous GeTe crystallized. This is attributed to states about 6 eV above EF and it is concluded that these largely d-like states are more affected by the order-disorder transformation than the lower sp bands.
Bookmarks Related papers MentionsView impact
Ambio, 2016
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Physical Review A, 2015
Fragmentation of gas-phase chloro-and bromoacetic acid samples, particularly its dependency on th... more Fragmentation of gas-phase chloro-and bromoacetic acid samples, particularly its dependency on the atomic site of the initial core ionization, was studied in photoelectron-photoion-photoion coincidence (PEPIPICO) measurements. The fragmentation was investigated after ionizing carbon 1s and bromine 3d or chlorine 2p core orbitals. It was observed that the samples had many similar fragmentation pathways and that their relative weights depended strongly on the initial ionization site. Additional Auger PEPIPICO measurements revealed a clear dependence of fragment pair intensities on the kinetic energy of the emitted Auger electrons. The modeled and measured Auger electron spectra indicated that the average internal energy of the molecule was larger following the carbon 1s core-hole decay than after the decay of the halogen core hole. This difference in the internal energies was found to be the source of the site-dependent photofragmentation behavior.
Bookmarks Related papers MentionsView impact