andrea gaetano chiariello | Università della Campania Luigi Vanvitelli (original) (raw)
Papers by andrea gaetano chiariello
IEEE transactions on plasma science, 2024
Inevitable inaccuracies in both manufacturing and assembly of magnetic field coils cause discrepa... more Inevitable inaccuracies in both manufacturing and assembly of magnetic field coils cause discrepancies between actual and nominal field in the plasma region, then generating error fields (EFs). This article examines the possibility to take advantage from the degrees of freedom (DoFs) of the assembly procedure to reduce the EFs due to a previously assembled part of the magnetic system in a tokamak. It is part of a broader vision that places the assembly phase within an optimization process able to take into account a full set of plasma scenarios. The effectiveness of the procedure is shown for the magnetic system of the divertor tokamak test (DTT) facility, currently under construction in Frascati, Italy.
Applied Computational Electromagnetics Society Journal, 2016
─ This paper presents fast computational techniques applied to modelling the RFX-mod fusion devic... more ─ This paper presents fast computational techniques applied to modelling the RFX-mod fusion device. An integral equation model is derived for the current distribution on the active coils of the conducting structures, and the input-output transfer functions are computed. Speed-up factors of about 200 can be obtained on hybrid CPU-GPU parallelization against uniprocessor computation. Index Terms ─ Fusion plasma devices, GPUs, HPC, integral formulation, parallelism.
Nuclear Fusion, 2019
Alfvén eigenmodes driven by energetic particles are routinely observed in tokamak plasmas. These ... more Alfvén eigenmodes driven by energetic particles are routinely observed in tokamak plasmas. These modes consist of poloidal harmonics of shear Alfvén waves coupled by inhomogeneity in the magnetic field. Further coupling is introduced by 3D inhomogeneities in the ion density during the assimilation of injected pellets. This additional coupling modifies the Alfvén continuum and discrete eigenmode spectrum. The frequencies of Alfvén eigenmodes drop dramatically when a pellet is injected in JET. From these observations, information about the changes in the ion density caused by a pellet can be inferred. To use Alfvén eigenmodes for MHD spectroscopy of pellet injected plasmas, the 3D MHD codes Stellgap and AE3D were generalised to incorporate 3D density profiles. A model for the expansion of the ionised pellet plasmoid along a magnetic field line was derived from the fluid equations. Thereby, the time evolution of the Alfvén eigenfrequency is reproduced. By comparing the numerical frequency drop of a toroidal Alfvén eigenmode (TAE) to experimental observations, the initial ion density of a cigar-shaped ablation region of length 4cm is estimated to be n * = 6.8×10 22 m −3 at the TAE location (r/a ≈ 0.75). The frequency sweeping of an Alfvén eigenmode ends when the ion density homogenises poloidally. Modelling suggests that the time for poloidal homogenisation of the ion density at the TAE position is τ h = 18 ± 4 ms for inboard pellet injection, and τ h = 26 ± 2 ms for outboard pellet injection. By reproducing the frequency evolution of the elliptical Alfvén eigenmode (EAE), the initial ion density at the EAE location (r/a ≈ 0.9) can be estimated to be n * = 4.8 × 10 22 m −3. Poloidal homogenisation of the ion density takes 2.7 times longer at the EAE location than at the TAE location for both inboard and outboard pellet injection. MHD spectroscopy, Alfvén eigenmodes, pellet injection ‡ See the author list of "Overview of the JET preparation for Deuterium-Tritium Operation" by E.
Nuclear Fusion, 2019
The present paper offers an overview of the potential of ion cyclotron resonance heating (ICRH) o... more The present paper offers an overview of the potential of ion cyclotron resonance heating (ICRH) or radio frequency heating for the DEMO machine. It is found that various suitable heating schemes are available. Similar to ITER and in view of the limited bandwidth of about 10 MHz that can be achieved to ensure optimal functioning of the launcher, it is proposed to make core second harmonic tritium heating the key ion heating scheme, assisted by fundamental cyclotron heating 3 He in the early phase of the discharge; for the present design of DEMO-with a static magnetic field strength of B o = 5.855 T-that places the T and 3 He layers in the core for f = 60 MHz and suggests centering the bandwidth around that main operating frequency. In line with earlier studies for hot, dense plasmas in large-size magnetic confinement machines, it is shown that good single pass absorption is achieved but that the size as well as the operating density and temperature of the machine cause the electrons to absorb a non-negligible fraction of the power away from the core when core ion heating is aimed at. Current drive and alternative heating options are briefly discussed and a dedicated computation is done for the traveling wave antenna, proposed for DEMO in view of its compatibility with substantial antenna-plasma distances. The various tasks that ICRH can fulfill are briefly listed. Finally, the impact of transport and the sensitivity of the obtained results to changes in the machine parameters is commented on.
Proceedings - 2011 International Conference on Electromagnetics in Advanced Applications, ICEAA'11, 2011
Abstract This paper provides a transmission line (TL) model for the propagation of electric signa... more Abstract This paper provides a transmission line (TL) model for the propagation of electric signals along multiwall carbon nanotube (MWCNT) interconnects in the low frequency regime where interband transitions are forbidden. The electrical parameters of the TL ...
… , 2009. IEEE-NANO 2009. …, 2009
I. INTRODUCTION Packaging will play a crucial role in enabling future nanoelectronics, by providi... more I. INTRODUCTION Packaging will play a crucial role in enabling future nanoelectronics, by providing the effective capability of complementing the nanometric device features to the circuit boards. Interconnecting the nanometric devices will be a major problem for technologies ...
The estimation of the unknown magnetic sources in Fusion devices by external measurements is a cr... more The estimation of the unknown magnetic sources in Fusion devices by external measurements is a critical task due to its impact on several actions, including the assessment of the magnetic diagnostic system. Suitably treating the modelling of ferromagnetic materials, a linear model can be used also in presence of iron, based on the use of equivalent magnetizing currents. The several available numerical approaches provide quite different solutions while all preserving a good representation capability.
International Journal of Numerical Modelling-electronic Networks Devices and Fields, Feb 14, 2013
The temperature effects on the electrical performance of a large area multicrystalline silicon so... more The temperature effects on the electrical performance of a large area multicrystalline silicon solar cell with back-contact technology have been studied in a desert area under ambient conditions using the current shunt measuring technique. Therefore, most of the problems encountered with traditional measuring techniques are avoided. The temperature dependency of the current shunt from 5ºC up to 50ºC has been investigated. Its temperature coefficient proves to be negligible which means that the temperature dependency of the solar cell is completely independent of the current shunt. The solar module installed in a tilted position at the optimum angle of the location, has been tested in two different seasons (winter and summer). The obtained solar cell short circuit current, open circuit voltage and output power are correlated with the measured incident radiation in both seasons and all results are discussed.
Fusion Engineering and Design
Fusion Engineering and Design
The Divertor Tokamak Test (DTT) facility, construction starting at Frascati, Italy, is designed t... more The Divertor Tokamak Test (DTT) facility, construction starting at Frascati, Italy, is designed to test different solutions for divertor in view of DEMO. A preliminary analysis of the error fields (EFs) assumed a simplified model of rigid and independent displacements and rotations. A methodology based on the first order truncated Taylor expansion has been applied, linking the displacement parameters and the EFs within the required accuracies. A system of in-vessel copper coils has been designed to counteract EFs and the ampere-turns necessary to force them back within the request limits has been calculated. Here, the details of the analysis have been provided.
2017 Computing and Electromagnetics International Workshop (CEM), 2017
This paper presents some innovative numerical techniques for the efficient treatment of non-linea... more This paper presents some innovative numerical techniques for the efficient treatment of non-linear magnetic materials in the evolution of plasma in thermonuclear fusion devices.
Fusion Engineering and Design, 2021
Abstract Due to the critical impact on the plasma control, the reliability of the magnetic diagno... more Abstract Due to the critical impact on the plasma control, the reliability of the magnetic diagnostic system in a tokamak should be continuously supervised. A new procedure based on a robust estimation of the expected field in the probe region and its comparison with the actual measurement has been recently proposed and assessed on several devices. The application of the procedure in the case of the Divertor Tokamak Test facility is here discussed.
IEEE Transactions on Magnetics, 2018
The information coming from the diagnostic system is of vital importance for the correct function... more The information coming from the diagnostic system is of vital importance for the correct functioning of many electromagnetic devices. In particular, for nuclear fusion devices, the magnetic measurements are used for a number of fundamental identification tasks such as equilibrium analysis and plasma boundary reconstruction. The quality and the reliability of the measurements strongly impact the final results; therefore, proper techniques able to detect faulty probes and to assess their effectiveness are very beneficial. When calibration and other self-consistency tools fail to detect loss of reliability, numerical approaches can help in detecting and eventually correcting information from the malfunctioning channels. This paper proposes a general approach for the fast identification of broken probes based on suitable reconstruction procedures. The approach is tested in Tokamak reactors, but it is quite general and it can be easily extended to other application fields.
2016 URSI International Symposium on Electromagnetic Theory (EMTS), 2016
We presents fast computational techniques applied to modelling the RFX-mod fusion device. We deri... more We presents fast computational techniques applied to modelling the RFX-mod fusion device. We derive an integral equation model for estimating the current distribution in the conducting structures, and we compute the input-output transfer functions. By using hybrid CPU-GPU parallelization, speed-up factors of about 200 can be obtained against uniprocessor computation.
IEEE Transactions on Magnetics, 2016
This paper introduces an analytical approach for an effective evaluation of the variation of the ... more This paper introduces an analytical approach for an effective evaluation of the variation of the magnetic field generated by complex coils due to deformations with respect to the nominal configuration. The coils are described with a set of synthetic design parameters, and the deformations can be described as variations of such parameters. This paper proposes a method to evaluate the derivatives of the magnetic field with respect to the design parameters by splitting them into a magnetic factor and a geometrical factor. A comparison with the classical finite-differences approach is carried out. This paper focuses on the context of sensitivity analysis, but the methodology is quite general and can easily be extended in other fields.
IEEE Transactions on Magnetics, 2015
ABSTRACT (c) 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be ... more ABSTRACT (c) 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.
IEEE Transactions on Magnetics, 2015
2011 IEEE Electrical Design of Advanced Packaging and Systems Symposium, EDAPS 2011, 2011
IEEE transactions on plasma science, 2024
Inevitable inaccuracies in both manufacturing and assembly of magnetic field coils cause discrepa... more Inevitable inaccuracies in both manufacturing and assembly of magnetic field coils cause discrepancies between actual and nominal field in the plasma region, then generating error fields (EFs). This article examines the possibility to take advantage from the degrees of freedom (DoFs) of the assembly procedure to reduce the EFs due to a previously assembled part of the magnetic system in a tokamak. It is part of a broader vision that places the assembly phase within an optimization process able to take into account a full set of plasma scenarios. The effectiveness of the procedure is shown for the magnetic system of the divertor tokamak test (DTT) facility, currently under construction in Frascati, Italy.
Applied Computational Electromagnetics Society Journal, 2016
─ This paper presents fast computational techniques applied to modelling the RFX-mod fusion devic... more ─ This paper presents fast computational techniques applied to modelling the RFX-mod fusion device. An integral equation model is derived for the current distribution on the active coils of the conducting structures, and the input-output transfer functions are computed. Speed-up factors of about 200 can be obtained on hybrid CPU-GPU parallelization against uniprocessor computation. Index Terms ─ Fusion plasma devices, GPUs, HPC, integral formulation, parallelism.
Nuclear Fusion, 2019
Alfvén eigenmodes driven by energetic particles are routinely observed in tokamak plasmas. These ... more Alfvén eigenmodes driven by energetic particles are routinely observed in tokamak plasmas. These modes consist of poloidal harmonics of shear Alfvén waves coupled by inhomogeneity in the magnetic field. Further coupling is introduced by 3D inhomogeneities in the ion density during the assimilation of injected pellets. This additional coupling modifies the Alfvén continuum and discrete eigenmode spectrum. The frequencies of Alfvén eigenmodes drop dramatically when a pellet is injected in JET. From these observations, information about the changes in the ion density caused by a pellet can be inferred. To use Alfvén eigenmodes for MHD spectroscopy of pellet injected plasmas, the 3D MHD codes Stellgap and AE3D were generalised to incorporate 3D density profiles. A model for the expansion of the ionised pellet plasmoid along a magnetic field line was derived from the fluid equations. Thereby, the time evolution of the Alfvén eigenfrequency is reproduced. By comparing the numerical frequency drop of a toroidal Alfvén eigenmode (TAE) to experimental observations, the initial ion density of a cigar-shaped ablation region of length 4cm is estimated to be n * = 6.8×10 22 m −3 at the TAE location (r/a ≈ 0.75). The frequency sweeping of an Alfvén eigenmode ends when the ion density homogenises poloidally. Modelling suggests that the time for poloidal homogenisation of the ion density at the TAE position is τ h = 18 ± 4 ms for inboard pellet injection, and τ h = 26 ± 2 ms for outboard pellet injection. By reproducing the frequency evolution of the elliptical Alfvén eigenmode (EAE), the initial ion density at the EAE location (r/a ≈ 0.9) can be estimated to be n * = 4.8 × 10 22 m −3. Poloidal homogenisation of the ion density takes 2.7 times longer at the EAE location than at the TAE location for both inboard and outboard pellet injection. MHD spectroscopy, Alfvén eigenmodes, pellet injection ‡ See the author list of "Overview of the JET preparation for Deuterium-Tritium Operation" by E.
Nuclear Fusion, 2019
The present paper offers an overview of the potential of ion cyclotron resonance heating (ICRH) o... more The present paper offers an overview of the potential of ion cyclotron resonance heating (ICRH) or radio frequency heating for the DEMO machine. It is found that various suitable heating schemes are available. Similar to ITER and in view of the limited bandwidth of about 10 MHz that can be achieved to ensure optimal functioning of the launcher, it is proposed to make core second harmonic tritium heating the key ion heating scheme, assisted by fundamental cyclotron heating 3 He in the early phase of the discharge; for the present design of DEMO-with a static magnetic field strength of B o = 5.855 T-that places the T and 3 He layers in the core for f = 60 MHz and suggests centering the bandwidth around that main operating frequency. In line with earlier studies for hot, dense plasmas in large-size magnetic confinement machines, it is shown that good single pass absorption is achieved but that the size as well as the operating density and temperature of the machine cause the electrons to absorb a non-negligible fraction of the power away from the core when core ion heating is aimed at. Current drive and alternative heating options are briefly discussed and a dedicated computation is done for the traveling wave antenna, proposed for DEMO in view of its compatibility with substantial antenna-plasma distances. The various tasks that ICRH can fulfill are briefly listed. Finally, the impact of transport and the sensitivity of the obtained results to changes in the machine parameters is commented on.
Proceedings - 2011 International Conference on Electromagnetics in Advanced Applications, ICEAA'11, 2011
Abstract This paper provides a transmission line (TL) model for the propagation of electric signa... more Abstract This paper provides a transmission line (TL) model for the propagation of electric signals along multiwall carbon nanotube (MWCNT) interconnects in the low frequency regime where interband transitions are forbidden. The electrical parameters of the TL ...
… , 2009. IEEE-NANO 2009. …, 2009
I. INTRODUCTION Packaging will play a crucial role in enabling future nanoelectronics, by providi... more I. INTRODUCTION Packaging will play a crucial role in enabling future nanoelectronics, by providing the effective capability of complementing the nanometric device features to the circuit boards. Interconnecting the nanometric devices will be a major problem for technologies ...
The estimation of the unknown magnetic sources in Fusion devices by external measurements is a cr... more The estimation of the unknown magnetic sources in Fusion devices by external measurements is a critical task due to its impact on several actions, including the assessment of the magnetic diagnostic system. Suitably treating the modelling of ferromagnetic materials, a linear model can be used also in presence of iron, based on the use of equivalent magnetizing currents. The several available numerical approaches provide quite different solutions while all preserving a good representation capability.
International Journal of Numerical Modelling-electronic Networks Devices and Fields, Feb 14, 2013
The temperature effects on the electrical performance of a large area multicrystalline silicon so... more The temperature effects on the electrical performance of a large area multicrystalline silicon solar cell with back-contact technology have been studied in a desert area under ambient conditions using the current shunt measuring technique. Therefore, most of the problems encountered with traditional measuring techniques are avoided. The temperature dependency of the current shunt from 5ºC up to 50ºC has been investigated. Its temperature coefficient proves to be negligible which means that the temperature dependency of the solar cell is completely independent of the current shunt. The solar module installed in a tilted position at the optimum angle of the location, has been tested in two different seasons (winter and summer). The obtained solar cell short circuit current, open circuit voltage and output power are correlated with the measured incident radiation in both seasons and all results are discussed.
Fusion Engineering and Design
Fusion Engineering and Design
The Divertor Tokamak Test (DTT) facility, construction starting at Frascati, Italy, is designed t... more The Divertor Tokamak Test (DTT) facility, construction starting at Frascati, Italy, is designed to test different solutions for divertor in view of DEMO. A preliminary analysis of the error fields (EFs) assumed a simplified model of rigid and independent displacements and rotations. A methodology based on the first order truncated Taylor expansion has been applied, linking the displacement parameters and the EFs within the required accuracies. A system of in-vessel copper coils has been designed to counteract EFs and the ampere-turns necessary to force them back within the request limits has been calculated. Here, the details of the analysis have been provided.
2017 Computing and Electromagnetics International Workshop (CEM), 2017
This paper presents some innovative numerical techniques for the efficient treatment of non-linea... more This paper presents some innovative numerical techniques for the efficient treatment of non-linear magnetic materials in the evolution of plasma in thermonuclear fusion devices.
Fusion Engineering and Design, 2021
Abstract Due to the critical impact on the plasma control, the reliability of the magnetic diagno... more Abstract Due to the critical impact on the plasma control, the reliability of the magnetic diagnostic system in a tokamak should be continuously supervised. A new procedure based on a robust estimation of the expected field in the probe region and its comparison with the actual measurement has been recently proposed and assessed on several devices. The application of the procedure in the case of the Divertor Tokamak Test facility is here discussed.
IEEE Transactions on Magnetics, 2018
The information coming from the diagnostic system is of vital importance for the correct function... more The information coming from the diagnostic system is of vital importance for the correct functioning of many electromagnetic devices. In particular, for nuclear fusion devices, the magnetic measurements are used for a number of fundamental identification tasks such as equilibrium analysis and plasma boundary reconstruction. The quality and the reliability of the measurements strongly impact the final results; therefore, proper techniques able to detect faulty probes and to assess their effectiveness are very beneficial. When calibration and other self-consistency tools fail to detect loss of reliability, numerical approaches can help in detecting and eventually correcting information from the malfunctioning channels. This paper proposes a general approach for the fast identification of broken probes based on suitable reconstruction procedures. The approach is tested in Tokamak reactors, but it is quite general and it can be easily extended to other application fields.
2016 URSI International Symposium on Electromagnetic Theory (EMTS), 2016
We presents fast computational techniques applied to modelling the RFX-mod fusion device. We deri... more We presents fast computational techniques applied to modelling the RFX-mod fusion device. We derive an integral equation model for estimating the current distribution in the conducting structures, and we compute the input-output transfer functions. By using hybrid CPU-GPU parallelization, speed-up factors of about 200 can be obtained against uniprocessor computation.
IEEE Transactions on Magnetics, 2016
This paper introduces an analytical approach for an effective evaluation of the variation of the ... more This paper introduces an analytical approach for an effective evaluation of the variation of the magnetic field generated by complex coils due to deformations with respect to the nominal configuration. The coils are described with a set of synthetic design parameters, and the deformations can be described as variations of such parameters. This paper proposes a method to evaluate the derivatives of the magnetic field with respect to the design parameters by splitting them into a magnetic factor and a geometrical factor. A comparison with the classical finite-differences approach is carried out. This paper focuses on the context of sensitivity analysis, but the methodology is quite general and can easily be extended in other fields.
IEEE Transactions on Magnetics, 2015
ABSTRACT (c) 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be ... more ABSTRACT (c) 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.
IEEE Transactions on Magnetics, 2015
2011 IEEE Electrical Design of Advanced Packaging and Systems Symposium, EDAPS 2011, 2011