D. Moseev
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View article: Velocity-space tomography of MeV-range fast-ion distributions in JET using wave–particle interaction priors
Velocity-space tomography of MeV-range fast-ion distributions in JET using wave–particle interaction priors Open
The fast-ion distribution function in fusion plasmas can only be measured indirectly by solving an ill-posed inverse problem. The inversion being ill-posed necessitates regularisation of the problem to ensure that the reconstruction of the…
View article: Orbit-space sensitivity of two-step reaction gamma-ray spectroscopy
Orbit-space sensitivity of two-step reaction gamma-ray spectroscopy Open
We calculate the orbit-space sensitivity of two-step reaction gamma-ray spectroscopy diagnostics in toroidally symmetric magnetic equilibria, using the reaction between alpha particles and beryllium-9 as an example. To reduce the computati…
View article: Using ASCOT to encode neoclassical collisional physics as prior in fast-ion distribution reconstructions
Using ASCOT to encode neoclassical collisional physics as prior in fast-ion distribution reconstructions Open
Measuring 3D or 4D fast-ion distribution function relies on using prior information in some form due to the ill-conditioned nature of the underlying inverse problem. Here we present a method to encode the correlations between phase-space e…
View article: Velocity-space tomography of an MeV fast-ion tail generated by three-ion scheme ICRF heating at JET
Velocity-space tomography of an MeV fast-ion tail generated by three-ion scheme ICRF heating at JET Open
Recently-developed methods are used successfully to reconstruct the two-dimensional velocity-space distribution of the energetic minority MeV ion tail created by heating in the ion cyclotron range of frequencies (ICRFs) in the D–D – 3…
View article: Fast-ion phase-space tomography with wave–particle interactions in the ion cyclotron frequency range as prior
Fast-ion phase-space tomography with wave–particle interactions in the ion cyclotron frequency range as prior Open
The fast-ion distribution function in fusion plasmas can be inferred by inverting Doppler-shifted measurements from fast-ion diagnostics. The full fast-ion distribution function can be parametrised by three constants of motion with the add…
View article: Energetic particle physics: Chapter 7 of the special issue: on the path to tokamak burning plasma operation
Energetic particle physics: Chapter 7 of the special issue: on the path to tokamak burning plasma operation Open
We review the physics of energetic particles (EPs) in magnetically confined burning fusion plasmas with focus on advances since the last update of the ITER Physics Basis (Fasoli et al 2007 Nucl. Fusion 47 S264). Topics include basic EP phy…
View article: Generation of energetic electrons during X2 ECRH start up
Generation of energetic electrons during X2 ECRH start up Open
In the initial stages of plasma initiation in the Wendelstein7-X stellarator with electron-cyclotron-resonance heating, a downshifted electron cyclotron emission signal is observed. Due to the absence of a corresponding upshifted signal, t…
View article: An analytical model for two-step reaction gamma-ray spectroscopy in magnetized plasmas
An analytical model for two-step reaction gamma-ray spectroscopy in magnetized plasmas Open
We present a method to analytically compute gamma-ray spectra generated via two-step fusion reactions, where a gamma-ray is emitted from the excited nucleus generated in the first step of the reaction. If one reactant is energetic and the …
View article: A model for analytical calculations of synthetic neutron energy spectra from beam-target reactions
A model for analytical calculations of synthetic neutron energy spectra from beam-target reactions Open
We present a fully analytical model for calculating energy spectra of neutrons generated by fusion reactions involving a fast ion, or beam, and a stationary ion, or target, in magnetic fusion plasmas. For neutrons moving along the line-of-…
View article: Reconstruction of the fast-ion deuterium distribution in a tritium-rich plasma in the JET DTE2 campaign
Reconstruction of the fast-ion deuterium distribution in a tritium-rich plasma in the JET DTE2 campaign Open
An important step on the way to future fusion power plants was the 2021 deuterium–tritium experimental campaign (DTE2) at the Joint European Torus (JET), in which crucial DT physics was investigated. In this study, we have reconstructed th…
View article: Experimental and numerical investigation of the Doppler-shifted resonance condition for high frequency Alfvén eigenmodes on ASDEX Upgrade
Experimental and numerical investigation of the Doppler-shifted resonance condition for high frequency Alfvén eigenmodes on ASDEX Upgrade Open
The Doppler-shifted resonance condition for high frequency Alfvénic eigenmodes has been extensively studied on ASDEX Upgrade in the presence of one or a combination of two neutral beam injected (NBI) fast ion populations. In general, only …
View article: Optimization of fast-ion diagnostic sets in tokamaks and stellarators using diagnostic weight functions
Optimization of fast-ion diagnostic sets in tokamaks and stellarators using diagnostic weight functions Open
The fast-ion phase-space distribution function in the magnetic fusion devices is always underdiagnosed, and every new fast-ion diagnostic should be carefully assessed before installation to minimize redundancies in measurements and maximiz…
View article: Overview of Large Helical Device experiments of basic plasma physics for solving crucial issues in reaching burning plasma conditions
Overview of Large Helical Device experiments of basic plasma physics for solving crucial issues in reaching burning plasma conditions Open
Recently, experiments on basic plasma physics issues for solving future problems in fusion energy have been performed on a Large Helical Device. There are several problems to be solved in future devices for fusion energy. Emerging issues i…
View article: Orbit tomography in constants-of-motion phase-space
Orbit tomography in constants-of-motion phase-space Open
Tomographic reconstructions of a 3D fast-ion constants-of-motion phase-space distribution function are computed by inverting synthetic signals based on projected velocities of the fast ions along the diagnostic lines of sight. A spectrum o…
View article: Influence of sawtooth oscillations on fast ions in a stellarator
Influence of sawtooth oscillations on fast ions in a stellarator Open
Sawtooth oscillations in tokamaks frequently lead to the redistribution of energetic ions, mainly on passing orbits, causing their expulsion from the core. This paper discusses the first measurements of the interaction of fast ions and saw…
View article: Predicting ion cyclotron emission from neutral beam heated plasmas in Wendelstein7-X stellarator
Predicting ion cyclotron emission from neutral beam heated plasmas in Wendelstein7-X stellarator Open
Measurements of ion cyclotron emission (ICE) are planned for magnetically confined fusion plasmas heated by neutral beam injection (NBI) in the Wendelstein 7-X stellarator (W7-X). Freshly injected NBI ions in the edge region, whose velocit…
View article: Commissioning and first results of the 174 GHz collective Thomson scattering diagnostic at Wendelstein 7-X
Commissioning and first results of the 174 GHz collective Thomson scattering diagnostic at Wendelstein 7-X Open
Collective Thomson Scattering (CTS) diagnostics measure the scattering spectrum of monochromatic incident radiation off collective fluctuations in the plasma. In this contribution, we present the first results from the upgraded CTS diagnos…
View article: Diagnostic weight functions in constants-of-motion phase-space
Diagnostic weight functions in constants-of-motion phase-space Open
The fast-ion phase-space distribution function in axisymmetric tokamak plasmas is completely described by the three constants of motion: energy, magnetic moment and toroidal canonical angular momentum. In this work, the observable regions …
View article: Development of the 174 GHz collective Thomson scattering diagnostics at Wendelstein 7-X
Development of the 174 GHz collective Thomson scattering diagnostics at Wendelstein 7-X Open
In this paper, we present the design and commissioning results of the upgraded collective Thomson scattering diagnostic at the Wendelstein 7-X stellarator. The diagnostic has a new radiometer designed to operate between the second and thir…
View article: Interpretation of ion cyclotron emission from sub-Alfvénic beam-injected ions heated plasmas soon after L-H mode transition in EAST
Interpretation of ion cyclotron emission from sub-Alfvénic beam-injected ions heated plasmas soon after L-H mode transition in EAST Open
Ion cyclotron emission (ICE) at deuterium ion cyclotron harmonics, driven by sub-Alfvénic beam-injected deuterium ions, has been observed by the high-frequency B-dot probe in the EAST tokamak. The origin of ICE shifts from the plasma core …
View article: 4D and 5D phase-space tomography using slowing-down physics regularization
4D and 5D phase-space tomography using slowing-down physics regularization Open
We compute reconstructions of 4D and 5D fast-ion phase-space distribution functions in fusion plasmas from synthetic projections of these functions. The fast-ion phase-space distribution functions originating from neutral beam injection (N…
View article: Analysis of high frequency Alfvén eigenmodes observed in ASDEX Upgrade plasmas in the presence of RF-accelerated NBI ions
Analysis of high frequency Alfvén eigenmodes observed in ASDEX Upgrade plasmas in the presence of RF-accelerated NBI ions Open
High frequency Alfvén eigenmodes in the ion cyclotron frequency range are actively researched on the ASDEX Upgrade tokamak (AUG). The general properties of this particular mode type are: ( a ) the mode is beam-driven and, if excited, can p…
View article: MISTRAL campaign in support of W7-X long pulse operation
MISTRAL campaign in support of W7-X long pulse operation Open
Following two initial campaigns [1], Stellarator Wendelstein 7-X (W7-X) has now completed the construction phase by installation of active cooling of all plasma facing components. The machine is presently commissioned for the next campaign…
View article: The ECRH-Power Upgrade at the Wendelstein 7-X Stellarator
The ECRH-Power Upgrade at the Wendelstein 7-X Stellarator Open
The existing ECRH system at W7-X consists of 10 gyrotrons, with output power levels ranging from 0.6 MW up to 1.0 MW each at a frequency of 140 GHz, quasi-optical transmission lines and microwave launchers at the plasma vessel. Compared to…
View article: Overview of plasma emissions observed in the ion cyclotron frequency range on ASDEX upgrade
Overview of plasma emissions observed in the ion cyclotron frequency range on ASDEX upgrade Open
In this work we present an overview of ion cyclotron emission (ICE) signals observed on ASDEX Upgrade (AUG) with a B-dot probe array [1]. The array was recently augmented with an 8 channel digitizer (up to 250 MHz sampling rate) that makes…
View article: Characterization of correlations of fast-ion H-alpha measurement volumes in Wendelstein 7-X by particle tracking
Characterization of correlations of fast-ion H-alpha measurement volumes in Wendelstein 7-X by particle tracking Open
This paper characterizes the correlation of simultaneous measurements with different fast-ion H-alpha (FIDA) spectroscopy sightlines on Wendelstein 7-X. Using a collisionless guiding-center code, it is shown that, for two investigated volu…