F. Castelli, S. Cialdi, G. Costantini, R. Ferragut, M. Giammarchi, G. Gittini, M. Leone, G. Maero, S. Olivares, M. Romé, A. Simonetto, V. Toso
{"title":"Loss and revival of coherence in the interaction between a positron beam and a photon field","authors":"F. Castelli, S. Cialdi, G. Costantini, R. Ferragut, M. Giammarchi, G. Gittini, M. Leone, G. Maero, S. Olivares, M. Romé, A. Simonetto, V. Toso","doi":"10.1017/s0022377823001319","DOIUrl":"https://doi.org/10.1017/s0022377823001319","url":null,"abstract":"We study the interaction between a positron beam in the single-particle regime in an interferometric configuration and a microwave electromagnetic field. We discuss the conditions under which quantum interference can be affected by the field and we outline its possible experimental study in the framework of QUantum interferometry and gravitation with Positrons and LASers (QUPLAS) experiment.","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139053412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Deller, C.W. Rogge, S. Desopo, E.V. Stenson, J.R. Danielson, M.R. Stoneking, C. Hugenschmidt, T. Sunn Pedersen, C.M. Surko
{"title":"A buffer-gas trap for the NEPOMUC positron beam: optimization studies with electrons","authors":"A. Deller, C.W. Rogge, S. Desopo, E.V. Stenson, J.R. Danielson, M.R. Stoneking, C. Hugenschmidt, T. Sunn Pedersen, C.M. Surko","doi":"10.1017/s0022377823001241","DOIUrl":"https://doi.org/10.1017/s0022377823001241","url":null,"abstract":"<p>Buffer-gas traps (BGTs) use inelastic interactions with nitrogen molecules to capture positrons from a continuous beam. These devices are invaluable for high-resolution studies of matter–antimatter interactions, antihydrogen research and positronium laser spectroscopy. We present a new project with the goal of producing a non-neutral plasma containing <span><span><span data-mathjax-type=\"texmath\"><span>${sim }10^8$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231220092024360-0938:S0022377823001241:S0022377823001241_inline1.png\"/></span></span> low-energy positrons by installing a BGT on the NEPOMUC (NEutron induced POsitron source MUniCh) high-intensity positron beam. Details of the BGT are outlined and results are presented from experiments in which an electron beam, with a similar intensity and energy spread to the remoderated NEPOMUC beam, was used to create pulses of non-neutral electron plasma. The device is a vital component of the APEX (A Positron Electron eXperiment) project, which aims to create a low-temperature electron–positron pair plasma.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138826081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aduragbemi A.T. Jibodu, Arnaud M. Ballande, Mark A. Cappelli
{"title":"Quadruple Langmuir probe characterization of different fuel gases in a plasma deflagration accelerator","authors":"Aduragbemi A.T. Jibodu, Arnaud M. Ballande, Mark A. Cappelli","doi":"10.1017/s0022377823001381","DOIUrl":"https://doi.org/10.1017/s0022377823001381","url":null,"abstract":"<p>Astrophysical flows may be studied by reproducing similar conditions using a coaxial plasma accelerator operating in the deflagration regime (or plasma deflagration accelerator). This allows for the recreation and investigation of dynamics present in complex highly coupled plasma systems at the laboratory scale. We report on measurements of the plasma density, temperature, plasma potential and velocity found using a quadruple Langmuir probe (QLP) on such a deflagration accelerator in the form of the Stanford Coaxial High ENerGy (CHENG) device operating with multiple gases – specifically argon, nitrogen and hydrogen. Experiments show a general decrease in bulk plasma velocity with gas atomic mass from upwards of <span><span><span data-mathjax-type=\"texmath\"><span>$120 {rm km} {rm s}^{-1}$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231219053848574-0922:S0022377823001381:S0022377823001381_inline1.png\"/></span></span> with hydrogen to less than <span><span><span data-mathjax-type=\"texmath\"><span>$30 {rm km} {rm s}^{-1}$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231219053848574-0922:S0022377823001381:S0022377823001381_inline2.png\"/></span></span> with argon. There was an accompanying increase in peak plasma density with increasing atomic mass from <span><span><span data-mathjax-type=\"texmath\"><span>${sim }3times 10^{20} {rm m}^{-3}$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231219053848574-0922:S0022377823001381:S0022377823001381_inline3.png\"/></span></span> with hydrogen to <span><span><span data-mathjax-type=\"texmath\"><span>${sim }1.5 times 10^{21} {rm m}^{-3}$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231219053848574-0922:S0022377823001381:S0022377823001381_inline4.png\"/></span></span> with argon. It was found that the momentum flux and internal energy density also generally increase with atomic mass while the particle flux is constant between shots. Further investigation is needed to understand these correlations and the underlying physics. Lastly, comparisons with scaling laws show that while the CHENG device may be operated in such a way as to simulate the effects of bulk solar wind movement, it may not properly capture the thermal effects.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138821844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Helicity of the magnetic axes of quasi-isodynamic stellarators","authors":"Katia Camacho Mata, Gabriel G. Plunk","doi":"10.1017/s0022377823001204","DOIUrl":"https://doi.org/10.1017/s0022377823001204","url":null,"abstract":"<p>In this study, we explore the influence of the helicity of the magnetic axis – defined as the self-linking number of the curve – on the quality of quasi-isodynamic stellarator-symmetric configurations constructed using the near-axis expansion method (Plunk <span>et al.</span>, <span>J. Plasma Phys.</span>, vol. 85, 2019, 905850602; Camacho Mata <span>et al.</span>, <span>J. Plasma Phys.</span>, vol. 88, 2022, 905880503). A class of magnetic axes previously unexplored within this formalism is identified when analysing the axis shape of the QIPC configuration (Subbotin <span>et al.</span>, <span>Nucl. Fusion</span>, vol. 46, 2006, p. 921): the case of half-helicity (per field period). We show that these shapes are compatible with the near-axis formalism and how they can be used to construct near-axis stellarators with up to five field periods, <span><span><span data-mathjax-type=\"texmath\"><span>$defiotaslash{{require{HTML} style{display: inline-block; transform: rotate(-13deg)}{iota}}kern-7pt{require{HTML} style{display: inline-block; transform: rotate(-25deg)}{-}}}{epsilon _{mathrm {eff}}} approx 1.3,%$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231215155329581-0753:S0022377823001204:S0022377823001204_inline1.png\"/></span></span>, and similar rotational transform to existing conventionally optimized designs, without the need of a plasma boundary optimization.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138716817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D.J. Murtagh, C. Amsler, H. Breuker, M. Bumbar, S. Chesnevskaya, G. Costantini, R. Ferragut, M. Giammarchi, A. Gligorova, G. Gosta, H. Higaki, E.D. Hunter, C. Killian, V. Kraxberger, N. Kuroda, A. Lanz, M. Leali, G. Maero, C. Malbrunot, V. Mascagna, Y. Matsuda, V. Mäckel, S. Migliorati, A. Nanda, L. Nowak, F. Parnefjord Gustafsson, S. Rheinfrank, M. Romé, M.C. Simon, M. Tajima, V. Toso, S. Ulmer, L. Venturelli, A. Weiser, E. Widmann, T. Wolz, Y. Yamazaki, J. Zmeskal
{"title":"Slow positron production and storage for the ASACUSA-Cusp experiment","authors":"D.J. Murtagh, C. Amsler, H. Breuker, M. Bumbar, S. Chesnevskaya, G. Costantini, R. Ferragut, M. Giammarchi, A. Gligorova, G. Gosta, H. Higaki, E.D. Hunter, C. Killian, V. Kraxberger, N. Kuroda, A. Lanz, M. Leali, G. Maero, C. Malbrunot, V. Mascagna, Y. Matsuda, V. Mäckel, S. Migliorati, A. Nanda, L. Nowak, F. Parnefjord Gustafsson, S. Rheinfrank, M. Romé, M.C. Simon, M. Tajima, V. Toso, S. Ulmer, L. Venturelli, A. Weiser, E. Widmann, T. Wolz, Y. Yamazaki, J. Zmeskal","doi":"10.1017/s0022377823001034","DOIUrl":"https://doi.org/10.1017/s0022377823001034","url":null,"abstract":"<p>The ASACUSA (atomic spectroscopy and collisions using slow antiprotons) Cusp experiment requires the production of dense positron plasmas with a high repetition rate to produce a beam of antihydrogen. In this work, details of the positron production apparatus used for the first observation of the antihydrogen beam, and subsequent measurements, are described in detail. This apparatus replaced the previous compact trap design resulting in an improvement in the positron accumulation rate by a factor of <span><span><span data-mathjax-type=\"texmath\"><span>$52pm 3$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231215104706423-0809:S0022377823001034:S0022377823001034_inline4.png\"/></span></span>.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138716691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mohamad Shalaby, Timon Thomas, Christoph Pfrommer, Rouven Lemmerz, Virginia Bresci
{"title":"Deciphering the physical basis of the intermediate-scale instability","authors":"Mohamad Shalaby, Timon Thomas, Christoph Pfrommer, Rouven Lemmerz, Virginia Bresci","doi":"10.1017/s0022377823001289","DOIUrl":"https://doi.org/10.1017/s0022377823001289","url":null,"abstract":"<p>We study the underlying physics of cosmic ray (CR)-driven instabilities that play a crucial role for CR transport across a wide range of scales, from interstellar to galaxy cluster environments. By examining the linear dispersion relation of CR-driven instabilities in a magnetised electron–ion background plasma, we establish that both the intermediate and gyroscale instabilities have a resonant origin, and show that these resonances can be understood via a simple graphical interpretation. These instabilities destabilise wave modes parallel to the large-scale background magnetic field at significantly distinct scales and with very different phase speeds. Furthermore, we show that approximating the electron–ion background plasma with either magnetohydrodynamics (MHD) or Hall-MHD fails to capture the fastest-growing instability in the linear regime, namely the intermediate-scale instability. This finding highlights the importance of accurately characterising the background plasma for resolving the most unstable wave modes. Finally, we discuss the implications of the different phase speeds of unstable modes on particle–wave scattering. Further work is needed to investigate the relative importance of these two instabilities in the nonlinear, saturated regime and to develop a physical understanding of the effective CR transport coefficients in large-scale CR hydrodynamics theories.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138572080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The nonlinear evolution of whistler-mode chorus: modulation instability as the source of tones","authors":"Daniel J. Ratliff, Oliver Allanson","doi":"10.1017/s0022377823001265","DOIUrl":"https://doi.org/10.1017/s0022377823001265","url":null,"abstract":"<p>We review the modulation stability of parallel-propagating/field-aligned whistler-mode chorus (WMC) waves propagating in a warm plasma from a formal perspective with a focus on wave–particle interactions via ponderomotive forces. The modulation instability criteria are characterised by the group velocity dispersion, <span><span><span data-mathjax-type=\"texmath\"><span>$d c_g/dk$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231209135147911-0331:S0022377823001265:S0022377823001265_inline1.png\"/></span></span>, for whistler-mode waves and a condition on the ratio between the group velocity <span><span><span data-mathjax-type=\"texmath\"><span>$c_g$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231209135147911-0331:S0022377823001265:S0022377823001265_inline2.png\"/></span></span> and the electron sound speed <span><span><span data-mathjax-type=\"texmath\"><span>$c_{s,e}$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231209135147911-0331:S0022377823001265:S0022377823001265_inline3.png\"/></span></span>. We also demonstrate that in order to investigate the spatiotemporal evolution of the envelope and the formation of packets (according to this mechanism), one necessarily needs to account for the motion of ions within the system, leading to an ionic influence on the modulation instability threshold determined by the ion fraction of the plasma. Finally, we demonstrate that chirping may be captured when higher-order effects are included within the spatiotemporal evolution of the amplitude. This yields not only an explicit expression for the sweep rate but also identifies a possible origin for the power band gap that occurs at half the electron gyrofrequency. Numerical validation demonstrates that the interaction between wave packets is a source for the emergence of tones observed within mission data, and such interactions may be a major source of the electron energisation which WMC are responsible for.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138574954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Hall magnetohydrodynamics in a relativistically strong mean magnetic field","authors":"Y. Kawazura","doi":"10.1017/s0022377823001228","DOIUrl":"https://doi.org/10.1017/s0022377823001228","url":null,"abstract":"<p>This paper presents a magnetohydrodynamic model that describes the small-amplitude fluctuations with wavelengths comparable to ion inertial length in the presence of a relativistically strong mean magnetic field. The set of derived equations is virtually identical to the non-relativistic Hall reduced magnetohydrodynamics (Schekochihin <span>et al.</span>, <span>J. Plasma Phys.</span>, vol. 85, 2019, 905850303), differing only by a few constants that take into account the relativistic corrections. This means that all the properties of kinetic Alfvén turbulence and ion cyclotron turbulence inherent in the non-relativistic Hall regime persist unchanged even in a magnetically dominated regime.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138572173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Axel Brandenburg, Ramkishor Sharma, Tanmay Vachaspati
{"title":"Inverse cascading for initial magnetohydrodynamic turbulence spectra between Saffman and Batchelor","authors":"Axel Brandenburg, Ramkishor Sharma, Tanmay Vachaspati","doi":"10.1017/s0022377823001253","DOIUrl":"https://doi.org/10.1017/s0022377823001253","url":null,"abstract":"In decaying magnetohydrodynamic (MHD) turbulence with a strong magnetic field, the spectral magnetic energy density is known to increase with time at small wavenumbers <jats:inline-formula> <jats:alternatives> <jats:tex-math>$k$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377823001253_inline1.png\" /> </jats:alternatives> </jats:inline-formula>, provided the spectrum at low <jats:inline-formula> <jats:alternatives> <jats:tex-math>$k$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377823001253_inline2.png\" /> </jats:alternatives> </jats:inline-formula> is sufficiently steep. This process is called inverse cascading and occurs for an initial Batchelor spectrum, where the magnetic energy per linear wavenumber interval increases like <jats:inline-formula> <jats:alternatives> <jats:tex-math>$k^4$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377823001253_inline3.png\" /> </jats:alternatives> </jats:inline-formula>. For an initial Saffman spectrum that is proportional to <jats:inline-formula> <jats:alternatives> <jats:tex-math>$k^2$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377823001253_inline4.png\" /> </jats:alternatives> </jats:inline-formula>, however, inverse cascading has not been found in the past. We study here the case of an intermediate <jats:inline-formula> <jats:alternatives> <jats:tex-math>$k^3$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377823001253_inline5.png\" /> </jats:alternatives> </jats:inline-formula> spectrum, which may be relevant for magnetogenesis in the early Universe during the electroweak epoch. This case is not well understood in view of the standard Taylor expansion of the magnetic energy spectrum for small <jats:inline-formula> <jats:alternatives> <jats:tex-math>$k$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377823001253_inline6.png\" /> </jats:alternatives> </jats:inline-formula>. Using high resolution MHD simulations, we show that, also in this case, there is inverse cascading with a strength just as expected from the conservation of the Hosking integral, which governs the decay of an initial Batchelor spectrum. Even for shallower <jats:inline-formula> <jats:alternatives> <jats:tex-math>$k^alpha$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377823001253_inline7.png\" /> </jats:alternatives> </jats:inline-formula> spectra with spectral index <jats:inline-formula> <jats:alternatives> <jats:tex-math>$alpha >3/2$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377823","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138525248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L.A. Leppin, T. Görler, M. Cavedon, M.G. Dunne, E. Wolfrum, F. Jenko, the ASDEX Upgrade Team
{"title":"Complex structure of turbulence across the ASDEX Upgrade pedestal","authors":"L.A. Leppin, T. Görler, M. Cavedon, M.G. Dunne, E. Wolfrum, F. Jenko, the ASDEX Upgrade Team","doi":"10.1017/s0022377823001101","DOIUrl":"https://doi.org/10.1017/s0022377823001101","url":null,"abstract":"<p>The theoretical investigation of relevant turbulent transport mechanisms in H-mode pedestals is a great scientific and numerical challenge. In this study, we address this challenge by global, nonlinear gyrokinetic simulations of a full pedestal up to the separatrix, supported by a detailed characterisation of gyrokinetic instabilities from just inside the pedestal top to the pedestal centre and foot. We present ASDEX Upgrade pedestal simulations using an upgraded version of the gyrokinetic, Eulerian, delta-f code GENE (genecode.org) that enables stable global simulations at experimental plasma <span><span><span data-mathjax-type=\"texmath\"><span>$beta$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231130170906058-0085:S0022377823001101:S0022377823001101_inline1.png\"/></span></span> values. The turbulent transport is found to exhibit a multi-channel, multi-scale character throughout the pedestal with the dominant contribution transitioning from ion-scale trapped electron modes/micro-tearing modes at the pedestal top to electron-scale electron temperature gradient modes in the steep gradient region. Consequently, the turbulent electron heat flux changes from ion to electron scales and the ion heat flux reduces to almost neoclassic values in the pedestal centre. <span><span><span data-mathjax-type=\"texmath\"><span>$Etimes B$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20231130170906058-0085:S0022377823001101:S0022377823001101_inline2.png\"/></span></span> shear is found to strongly reduce heat flux levels in all channels (electron, ion, electrostatic, electromagnetic) and the interplay of magnetic shear and pressure gradient is found to locally stabilise ion-scale instabilities.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138525245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}