Pub Date : 2025-09-01DOI: 10.1016/j.fpp.2025.100098
J. Biu , R. Jorge
Stellarators are fusion energy devices that confine a plasma using non-axisymmetric magnetic fields. Complex coils with tight construction tolerances are needed to create such fields. To simplify such coils, we use a method here to create filamentary curves bounded to a coil winding surface. This approach bypasses the need to find contours of the current potential in that surface while allowing gradients to be obtained for both the winding surface and the coil shapes. The parameterization of the coil curves allows the modeling of both modular and helical coils. As an application, we optimize a set of coils to reproduce a quasisymmetric stellarator equilibrium. A comparison is performed between coils parameterized in two different winding surfaces, namely an axisymmetric circular toroidal surface and a surface rescaled from the plasma boundary. Finally, an analysis is performed on the optimal distance between the plasma and the coil winding surface.
{"title":"Axisymmetric coil winding surfaces for non-axisymmetric fusion devices","authors":"J. Biu , R. Jorge","doi":"10.1016/j.fpp.2025.100098","DOIUrl":"10.1016/j.fpp.2025.100098","url":null,"abstract":"<div><div>Stellarators are fusion energy devices that confine a plasma using non-axisymmetric magnetic fields. Complex coils with tight construction tolerances are needed to create such fields. To simplify such coils, we use a method here to create filamentary curves bounded to a coil winding surface. This approach bypasses the need to find contours of the current potential in that surface while allowing gradients to be obtained for both the winding surface and the coil shapes. The parameterization of the coil curves allows the modeling of both modular and helical coils. As an application, we optimize a set of coils to reproduce a quasisymmetric stellarator equilibrium. A comparison is performed between coils parameterized in two different winding surfaces, namely an axisymmetric circular toroidal surface and a surface rescaled from the plasma boundary. Finally, an analysis is performed on the optimal distance between the plasma and the coil winding surface.</div></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"15 ","pages":"Article 100098"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145107691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-01DOI: 10.1016/j.fpp.2025.100096
Emilia R. Solano
The recent ITER re-baselining calls for new fusion-relevant research best carried out in a DT-capable tokamak device with similar technical choices. The present paper describes key issues that could be addressed in a Suitably Enhanced DT-capable Tokamak (SET), with tungsten plasma facing components, boronization systems, and 10 MW of ECRH, based on JET’s characteristics and knowledgebase. We discuss hardware options, and show that fusion-relevant operational scenarios could be achieved. Notably, development, validation and testing of fusion and nuclear diagnostics, to be used in next generation devices, would require a DT-capable tokamak as described.
{"title":"Fusion research in a Deuterium-Tritium tokamak","authors":"Emilia R. Solano","doi":"10.1016/j.fpp.2025.100096","DOIUrl":"10.1016/j.fpp.2025.100096","url":null,"abstract":"<div><div>The recent ITER re-baselining calls for new fusion-relevant research best carried out in a DT-capable tokamak device with similar technical choices. The present paper describes key issues that could be addressed in a Suitably Enhanced DT-capable Tokamak (SET), with tungsten plasma facing components, boronization systems, and 10 MW of ECRH, based on JET’s characteristics and knowledgebase. We discuss hardware options, and show that fusion-relevant operational scenarios could be achieved. Notably, development, validation and testing of fusion and nuclear diagnostics, to be used in next generation devices, would require a DT-capable tokamak as described.</div></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"15 ","pages":"Article 100096"},"PeriodicalIF":0.0,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145107732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-29DOI: 10.1016/j.fpp.2025.100092
Keiichiro Takeda , Naoki Sato
We present the noncanonical Hamiltonian structure of the relativistic Euler equations for a perfect fluid in Minkowski spacetime. By identifying the system’s noncanonical Poisson bracket and Hamiltonian, we show that relativistic fluid flows preserve helicity and enstrophy as conserved quantities in three-dimensional and two-dimensional cases, respectively. This holds when the fluid follows a relativistic -barotropic equation of state, which generalizes the classical barotropic condition. Furthermore, we demonstrate that these conserved quantities are Casimir invariants associated with the noncanonical Poisson structure. These findings open new avenues for applying Hamiltonian theory to the study of astrophysical fluids and relativistic plasmas.
{"title":"Revealing noncanonical Hamiltonian structures in relativistic fluid dynamics","authors":"Keiichiro Takeda , Naoki Sato","doi":"10.1016/j.fpp.2025.100092","DOIUrl":"10.1016/j.fpp.2025.100092","url":null,"abstract":"<div><div>We present the noncanonical Hamiltonian structure of the relativistic Euler equations for a perfect fluid in Minkowski spacetime. By identifying the system’s noncanonical Poisson bracket and Hamiltonian, we show that relativistic fluid flows preserve helicity and enstrophy as conserved quantities in three-dimensional and two-dimensional cases, respectively. This holds when the fluid follows a relativistic <span><math><mi>γ</mi></math></span>-barotropic equation of state, which generalizes the classical barotropic condition. Furthermore, we demonstrate that these conserved quantities are Casimir invariants associated with the noncanonical Poisson structure. These findings open new avenues for applying Hamiltonian theory to the study of astrophysical fluids and relativistic plasmas.</div></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"14 ","pages":"Article 100092"},"PeriodicalIF":0.0,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143912896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-13DOI: 10.1016/j.fpp.2025.100088
Anandam Choudhary , Laxman Prasad Goswami , C. Aparajit , Amit D. Lad , Ameya Parab , Yash M. Ved , Trishul Dhalia , Amita Das , G. Ravindra Kumar
The interaction of intense linearly polarized (LP) femtosecond laser pulses with solids is known to generate azimuthal magnetic fields, while circularly polarized (CP) light has been shown to create axial fields. We demonstrate through experiments and particle-in-cell simulations that circularly polarized light can generate both axial and azimuthal fields of comparable magnitude in a plasma created in a solid. Angular distributions of the generated fast electrons at the target front and rear show significant differences between the results for the two polarization states, with circular polarization enforcing more axial confinement. The measurement of the spatial distribution of both types of magnetic fields captures their turbulent evolution.
{"title":"Generation of mega-gauss axial and azimuthal magnetic fields in a solid plasma by ultrahigh intensity, circularly polarized femtosecond laser pulses","authors":"Anandam Choudhary , Laxman Prasad Goswami , C. Aparajit , Amit D. Lad , Ameya Parab , Yash M. Ved , Trishul Dhalia , Amita Das , G. Ravindra Kumar","doi":"10.1016/j.fpp.2025.100088","DOIUrl":"10.1016/j.fpp.2025.100088","url":null,"abstract":"<div><div>The interaction of intense linearly polarized (LP) femtosecond laser pulses with solids is known to generate azimuthal magnetic fields, while circularly polarized (CP) light has been shown to create axial fields. We demonstrate through experiments and particle-in-cell simulations that circularly polarized light can generate both axial and azimuthal fields of comparable magnitude in a plasma created in a solid. Angular distributions of the generated fast electrons at the target front and rear show significant differences between the results for the two polarization states, with circular polarization enforcing more axial confinement. The measurement of the spatial distribution of both types of magnetic fields captures their turbulent evolution.</div></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"14 ","pages":"Article 100088"},"PeriodicalIF":0.0,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143852144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-26DOI: 10.1016/j.fpp.2025.100087
Jonmoni Dutta , Ahmed Atteya , Pralay Kumar Karmakar
The presence of diverse negative ions is well-known to modify different collective waves and instabilities in diverse space and astrophysical environments. We herein investigate the stability dynamics of the spherical nonthermal (kappa-modified) pulsational mode of gravitational collapse (PMGC) excitable in astrophysical dust molecular clouds (DMCs). It primarily explores the impact of the realistic nonthermal negative ionic effects on the PMGC stability features. The high-energetic lighter constituents, such as the electrons, positive ions, and negative ions, are modelled with their respective nonthermal kappa ()-distribution laws. The inertial dust particulates are treated in the viscous fluid fabric. Application of spherical normal mode treatment results in a generalized linear quartic (degree-4) dispersion relation. A computational illustrative platform illuminates the underlying stabilizing and destabilizing factors. It is seen that the cloud size, dust mass, dust charge, nonthermality parameters, equilibrium charged dust number density, and neutral dust viscosity play stabilizing roles. It counters the destabilizing scenarios caused by the equilibrium electron number density, positive ion number density, negative ion number density, neutral dust density, and charged dust viscosity. The fundamental physical mechanisms responsible herein are substantiated and compared in light of the previous predictions. The nontrivial avenues of our study in realizing the Jeans-driven galactic structural unit formation processes, moderated actively with the presence of negative ions in diverse real astronomical circumstances are summarily indicated.
{"title":"Spherical nonthermal pulsational mode stability thermo-statistically moderated with extra-negative ions","authors":"Jonmoni Dutta , Ahmed Atteya , Pralay Kumar Karmakar","doi":"10.1016/j.fpp.2025.100087","DOIUrl":"10.1016/j.fpp.2025.100087","url":null,"abstract":"<div><div>The presence of diverse negative ions is well-known to modify different collective waves and instabilities in diverse space and astrophysical environments. We herein investigate the stability dynamics of the spherical nonthermal (kappa-modified) pulsational mode of gravitational collapse (PMGC) excitable in astrophysical dust molecular clouds (DMCs). It primarily explores the impact of the realistic nonthermal negative ionic effects on the PMGC stability features. The high-energetic lighter constituents, such as the electrons, positive ions, and negative ions, are modelled with their respective nonthermal kappa (<span><math><mi>κ</mi></math></span>)-distribution laws. The inertial dust particulates are treated in the viscous fluid fabric. Application of spherical normal mode treatment results in a generalized linear quartic (degree-4) dispersion relation. A computational illustrative platform illuminates the underlying stabilizing and destabilizing factors. It is seen that the cloud size, dust mass, dust charge, nonthermality parameters, equilibrium charged dust number density, and neutral dust viscosity play stabilizing roles. It counters the destabilizing scenarios caused by the equilibrium electron number density, positive ion number density, negative ion number density, neutral dust density, and charged dust viscosity. The fundamental physical mechanisms responsible herein are substantiated and compared in light of the previous predictions. The nontrivial avenues of our study in realizing the Jeans-driven galactic structural unit formation processes, moderated actively with the presence of negative ions in diverse real astronomical circumstances are summarily indicated.</div></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"14 ","pages":"Article 100087"},"PeriodicalIF":0.0,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143578458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-02DOI: 10.1016/j.fpp.2025.100086
B.N. Breizman , S.E. Sharapov
Instabilities of Alfvén eigenmodes (AEs) are of significant concern because they can enhance the cross-field transport of fusion-born alpha particles beyond the neoclassical level in magnetic fusion plasmas. The threshold value of alpha-particle pressure for exciting AEs depends critically on the damping rate of AEs. The damping mechanisms include kinetic damping due to interactions with thermal particles, continuum damping due to AE frequency crossing Alfvén continuum, and radiative damping due to emitting kinetic Alfvén waves (KAWs). The radiative damping is substantial and can even prevail in high-temperature burning plasmas [1]. We revisit the radiative damping analytic theory for TAE in plasmas with low positive magnetic shear, considering TAE with an eigenfrequency near the bottom of TAE-gap and with poloidal harmonics of the same sign (even TAE). In contrast to earlier papers, we provide the damping calculations in real space rather than Fourier space. This approach is straightforward technically and more enlightening from a physics standpoint for benchmarking numerical calculations of radiative damping. The parametric dependence of the resulting damping rate agrees with that of Refs. [2-5], but it has a smaller numerical factor in front of it.
{"title":"Radiative damping of toroidal Alfvén eigenmode in low-shear plasmas","authors":"B.N. Breizman , S.E. Sharapov","doi":"10.1016/j.fpp.2025.100086","DOIUrl":"10.1016/j.fpp.2025.100086","url":null,"abstract":"<div><div>Instabilities of Alfvén eigenmodes (AEs) are of significant concern because they can enhance the cross-field transport of fusion-born alpha particles beyond the neoclassical level in magnetic fusion plasmas. The threshold value of alpha-particle pressure for exciting AEs depends critically on the damping rate of AEs. The damping mechanisms include kinetic damping due to interactions with thermal particles, continuum damping due to AE frequency crossing Alfvén continuum, and radiative damping due to emitting kinetic Alfvén waves (KAWs). The radiative damping is substantial and can even prevail in high-temperature burning plasmas [1]. We revisit the radiative damping analytic theory for TAE in plasmas with low positive magnetic shear, considering TAE with an eigenfrequency near the bottom of TAE-gap and with poloidal harmonics of the same sign (even TAE). In contrast to earlier papers, we provide the damping calculations in real space rather than Fourier space. This approach is straightforward technically and more enlightening from a physics standpoint for benchmarking numerical calculations of radiative damping. The parametric dependence of the resulting damping rate agrees with that of Refs. [2-5], but it has a smaller numerical factor in front of it.</div></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"13 ","pages":"Article 100086"},"PeriodicalIF":0.0,"publicationDate":"2025-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-03DOI: 10.1016/j.fpp.2025.100085
Soheil Khoshbinfar
The magnetized target fusion (MTF) concept is considered an economic way to harness fusion energy that resides between two ICF and MCF pathways. Here, we have proposed a new DT fuel initial density profile that improves final fusion yield in cylindrical targets in MTF. We have employed the Deira-4 MHD code to investigate the performance of these configurations. The potential advantage of an initial density gradient over a common uniform profile assumption in inertial fusion energy is its higher energy gain at the cost of lower input driver energy. It was shown that its energy gain is higher by a factor of two and reduction in driver input energy by a factor of three for a fixed DT fuel mass regime, mDT∼2.2 mg. The radial density profile of DT fuel also promises to make larger targets that work at a sub-MJ regime which resolves our concern about the Rayleigh-Taylor instability growth rate during the implosion phase. It has also been shown that the best results with a seed axial magnetic field ∼10 T would be achieved for a power-law density profile, ρ∝rn, with an exponent n=3. Moreover, the optimal target geometry attains for initial aspect ratio of ∼15 and ignition threshold reduced from <ρR>DT,th=0.56 g/cm2 in uniform density of DT fuel to the power law density profile of ρ∝r3 to <ρR>DT,th =0.21 g/cm2.
{"title":"High energy gain of ion-driven flux compression in cylindrical target with initial power-law radial density profile","authors":"Soheil Khoshbinfar","doi":"10.1016/j.fpp.2025.100085","DOIUrl":"10.1016/j.fpp.2025.100085","url":null,"abstract":"<div><div>The magnetized target fusion (MTF) concept is considered an economic way to harness fusion energy that resides between two ICF and MCF pathways. Here, we have proposed a new DT fuel initial density profile that improves final fusion yield in cylindrical targets in MTF. We have employed the Deira-4 MHD code to investigate the performance of these configurations. The potential advantage of an initial density gradient over a common uniform profile assumption in inertial fusion energy is its higher energy gain at the cost of lower input driver energy. It was shown that its energy gain is higher by a factor of two and reduction in driver input energy by a factor of three for a fixed DT fuel mass regime, m<sub>DT</sub>∼2.2 mg. The radial density profile of DT fuel also promises to make larger targets that work at a sub-MJ regime which resolves our concern about the Rayleigh-Taylor instability growth rate during the implosion phase. It has also been shown that the best results with a seed axial magnetic field ∼10 T would be achieved for a power-law density profile, ρ∝r<sup>n</sup>, with an exponent n=3. Moreover, the optimal target geometry attains for initial aspect ratio of ∼15 and ignition threshold reduced from <ρR><sub>DT,th</sub>=0.56 g/cm<sup>2</sup> in uniform density of DT fuel to the power law density profile of ρ∝r<sup>3</sup> to <ρR><sub>DT,th</sub> =0.21 g/cm<sup>2</sup>.</div></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"13 ","pages":"Article 100085"},"PeriodicalIF":0.0,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143129831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-02DOI: 10.1016/j.fpp.2025.100084
M. Fitzgerald , B.N. Breizman
The linear response of a plasma to perturbations of arbitrary frequency and wavelength is derived for any axisymmetric magnetized toroidal plasma. An explicit transformation to action-angle coordinates is achieved using orthogonal magnetic coordinates and the Littlejohn Lagrangian, establishing the validity of this result to arbitrary order in normalized Larmor radius. The global resonance condition for compressional modes is clarified in more detail than in previous works, confirming that the poloidal orbit-average of the cyclotron frequency gives the desired result at lowest order in Larmor radius. The global plasma response to the perturbation at each resonance is captured by a poloidal and gyroaverage of the perturbing potential. A “global gyroaveraging” of the potential is a natural by-product of this analysis which takes into account the changing of the magnetic field over an orbit. The resonance condition depends on two arbitrary integers which completely separately capture the effects poloidal non-uniformity and finite Larmor radius in generating sidebands. We learn that poloidal sidebands generated for compressional modes are dominated by the change in gyrofrequency over the orbit, which is very different to shear modes where the gyrofrequency only contributes via a finite Larmor radius effect. This increases the number of bounce harmonics required to compute the linear drive, giving a more complicated resonance map. An example calculation is given comparing resonance of shear and compressional modes in a published DIII-D case.
{"title":"Solution of the linear wave-particle kinetic equation for global modes of arbitrary frequency in a tokamak","authors":"M. Fitzgerald , B.N. Breizman","doi":"10.1016/j.fpp.2025.100084","DOIUrl":"10.1016/j.fpp.2025.100084","url":null,"abstract":"<div><div>The linear response of a plasma to perturbations of arbitrary frequency and wavelength is derived for any axisymmetric magnetized toroidal plasma. An explicit transformation to action-angle coordinates is achieved using orthogonal magnetic coordinates and the Littlejohn Lagrangian, establishing the validity of this result to arbitrary order in normalized Larmor radius. The global resonance condition for compressional modes is clarified in more detail than in previous works, confirming that the poloidal orbit-average of the cyclotron frequency gives the desired result at lowest order in Larmor radius. The global plasma response to the perturbation at each resonance is captured by a poloidal and gyroaverage of the perturbing potential. A “global gyroaveraging” of the potential is a natural by-product of this analysis which takes into account the changing of the magnetic field over an orbit. The resonance condition depends on two arbitrary integers which completely separately capture the effects poloidal non-uniformity and finite Larmor radius in generating sidebands. We learn that poloidal sidebands generated for compressional modes are dominated by the change in gyrofrequency over the orbit, which is very different to shear modes where the gyrofrequency only contributes via a finite Larmor radius effect. This increases the number of bounce harmonics required to compute the linear drive, giving a more complicated resonance map. An example calculation is given comparing resonance of shear and compressional modes in a published DIII-D case.</div></div>","PeriodicalId":100558,"journal":{"name":"Fundamental Plasma Physics","volume":"13 ","pages":"Article 100084"},"PeriodicalIF":0.0,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143129830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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