Journal of Plasma Physics最新文献

{"title":"Mean-field transport equations and energy theorem for plasma edge turbulent transport","authors":"Reinart Coosemans, Wouter Dekeyser, Martine Baelmans","doi":"10.1017/s0022377824000163","DOIUrl":"https://doi.org/10.1017/s0022377824000163","url":null,"abstract":"This paper establishes a mean-field equation set and an energy theorem to provide a theoretical basis in view of the development of self-consistent, physics-based turbulent transport models for mean-field transport codes. A rigorous averaging procedure identifies the exact form of the perpendicular turbulent fluxes which are modelled by <jats:italic>ad hoc</jats:italic> diffusive terms in mean-field transport codes, next to other closure terms which are not commonly considered. Earlier work suggested that the turbulent <jats:inline-formula> <jats:alternatives> <jats:tex-math>$Etimes B$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377824000163_inline1.png\" /> </jats:alternatives> </jats:inline-formula> particle and heat fluxes, which are thus identified to be important closure terms, can be modelled to reasonable accuracy using the kinetic energy in the <jats:inline-formula> <jats:alternatives> <jats:tex-math>$Etimes B$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377824000163_inline2.png\" /> </jats:alternatives> </jats:inline-formula> velocity fluctuations (<jats:inline-formula> <jats:alternatives> <jats:tex-math>$k_{E}$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377824000163_inline3.png\" /> </jats:alternatives> </jats:inline-formula>). The related enstrophy led to further modelling improvements in an initial study, although further analysis is required. To support this modelling approach, transport equations are derived analytically for both quantities. In particular, an energy theorem is established in which the various source and sink terms of <jats:inline-formula> <jats:alternatives> <jats:tex-math>$k_{E}$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377824000163_inline4.png\" /> </jats:alternatives> </jats:inline-formula> are shown to couple to mean-field and turbulent parallel kinetic energy, kinetic energy in the other perpendicular velocity components, the thermal energy and the magnetic energy. This provides expressions for the interchange, drift-wave and Reynolds stress terms amongst others. Note that most terms in these energy equations are in turn closure terms. It is suggested to evaluate these terms using reference data from detailed turbulence code simulations in future work.","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"23 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140152495","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":"Experimental issues of energy balance in open magnetic trap","authors":"Elena I. Soldatkina, Andrey K. Meyster, Dmitry V. Yakovlev, Peter A. Bagryansky","doi":"10.1017/s0022377824000254","DOIUrl":"https://doi.org/10.1017/s0022377824000254","url":null,"abstract":"<p>The paper presents an overview of experimental results of an investigation of different energy loss channels in the gas dynamic trap (GDT), which is a magnetic mirror plasma confinement device in the Budker Institute of Nuclear Physics. Energy losses along magnetic field lines are considered as well as losses onto radial limiters, which restrict the plasma column radius and provide its magnetohydrodynamic stability via the ‘vortex confinement’ mechanism. The losses along the field lines were measured using a set of pyroelectric bolometers on the plasma absorber and the losses onto the limiters were determined with thermistors from their temperature rise. Additionally, the losses due to charge exchange of fast plasma ions on the residual neutral gas in the GDT were measured using a longitudinal array of pyroelectric bolometers mounted on the wall of the central cell. An attempt was made to draw up the energy balance in the GDT in order to identify the predominant loss channels and reduce those losses in the future.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"109 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140128125","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":"Development of a new magnetic mirror device at the Korea Advanced Institute of Science and Technology","authors":"D. Oh, M. Choe, G. Baek, D. Kim, B. K. Jung, K. J. Chung, I. Kourakis, C. Sung","doi":"10.1017/s0022377824000242","DOIUrl":"https://doi.org/10.1017/s0022377824000242","url":null,"abstract":"<p>A new magnetic mirror machine named KAIMIR (KAIST mirror) has been designed and constructed at the Korea Advanced Institute of Science and Technology (KAIST) to study mirror plasma physics and simulate the boundary regions of magnetic fusion plasmas such as in a tokamak. The purpose of this paper is to introduce the characteristics and initial experimental results of KAIMIR. The cylindrical vacuum chamber has a length of 2.48 m and a diameter of 0.5 m and consists of three sub-chambers, namely the source, centre and expander chambers. A magnetic mirror configuration is achieved by electromagnetic coils with a maximum magnetic field strength of 0.4 T at the mirror nozzles and 0.1 T at the centre. The source plasma is generated by a plasma washer gun installed in the source chamber with a pulse forming network system. The typical discharge time is ~12 ms with a ~6 ms (1–7 ms) steady period. Initial results show that the on-axis electron density at the centre is 10<span>19–20</span> m<span>−3</span> and the electron temperature is 4–7 eV. Two parameters were varied in this initial phase, the source power and the mirror ratio, which is the ratio of highest to lowest magnetic field strength in the mirror-confined region. We observed that the increase of the electron density was mitigated for a source power above 0.2 MW. It was also found that the electron density increases almost linearly with the mirror ratio. Accordingly, the stored electron energy was also linearly proportional to the mirror ratio, similar to the scaling of the gas dynamic trap.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"74 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140107468","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":"Modelling a thrust imparted by a highly ionized magnetic nozzle rf plasma thruster","authors":"Kazunori Takahashi","doi":"10.1017/s0022377824000266","DOIUrl":"https://doi.org/10.1017/s0022377824000266","url":null,"abstract":"<p>Influence of the local-ionization-induced neutral depletion on the thrust imparted by the magnetic nozzle plasma thruster is discussed by simply considering reduction of the neutral density due to the ionization in the thruster model combining the global source model and the one-dimensional magnetic nozzle model. When increasing the rf power, it is shown that the increase rate of the plasma density is reduced, while the electron temperature continues to increase due to a decrease in the neutral density. Since the major components of the thrust are originated from the electron pressures in the source and in the magnetic nozzle, the increase in the electron temperature contributes to the increase in the thrust in addition to the gradual density increase by the rf power. The model qualitatively predicts the reduction of the thruster efficiency by the neutral depletion for the high-power condition, compared with the constant neutral density model.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"142 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140055895","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":"Nonlinear electron scattering by electrostatic waves in collisionless shocks","authors":"Sergei R. Kamaletdinov, Ivan Y. Vasko, Anton V. Artemyev","doi":"10.1017/s0022377824000217","DOIUrl":"https://doi.org/10.1017/s0022377824000217","url":null,"abstract":"<p>We present a theoretical analysis of electron pitch-angle scattering by ion-acoustic electrostatic fluctuations present in the Earth's bow shock and, presumably, collisionless shocks in general. We numerically simulate electron interaction with a single wave packet to demonstrate the scattering through phase bunching and phase trapping and quantify electron pitch-angle scattering in dependence on the wave amplitude and wave normal angle to the local magnetic field. The iterative mapping technique is used to model pitch-angle scattering of electrons by a large number of wave packets, which have been reported in the Earth's bow shock. Assuming that successive electron scatterings are not correlated, we revealed that the long-term dynamics of electrons is diffusive. The diffusion coefficient depends on the ratio <span><span><span data-mathjax-type=\"texmath\"><span>$varPhi _0/W$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240306134914101-0214:S0022377824000217:S0022377824000217_inline1.png\"/></span></span> between the wave packet amplitude and electron energy, <span><span><span data-mathjax-type=\"texmath\"><span>$Dpropto (varPhi _0/W)^{nu }$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240306134914101-0214:S0022377824000217:S0022377824000217_inline2.png\"/></span></span>. A quasi-linear scaling (<span><span><span data-mathjax-type=\"texmath\"><span>$nu approx 2$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240306134914101-0214:S0022377824000217:S0022377824000217_inline3.png\"/></span></span>) is observed for sufficiently small wave amplitudes, <span><span><span data-mathjax-type=\"texmath\"><span>$varPhi _0lesssim 10^{-3}W$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240306134914101-0214:S0022377824000217:S0022377824000217_inline4.png\"/></span></span>, while the diffusion is nonlinear (<span><span><span data-mathjax-type=\"texmath\"><span>$1&lt;nu &lt;2$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240306134914101-0214:S0022377824000217:S0022377824000217_inline5.png\"/></span></span>) above this threshold. We show that pitch-angle diffusion of <span><span><span data-mathjax-type=\"texmath\"><span>${lesssim }1$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240306134914101-0214:S0022377824000217:S0022377824000217_inline6.png\"/></span></span> keV electrons in the Earth's bow shock can be nonlinear. The corresponding diffusion coefficient scales with the intensity <span><span><span data-mathjax-type=\"texmath\"><span>$E_{w}^{2}$<","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"118 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140055974","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":"Modulational instability of the interacting electron whistlers and magnetosonic perturbations","authors":"Jiao-Jiao Cheng, Fang-Ping Wang, Zhong-Zheng Li, Wen-Shan Duan","doi":"10.1017/s002237782400014x","DOIUrl":"https://doi.org/10.1017/s002237782400014x","url":null,"abstract":"A modulational instability of nonlinearly interacting electron whistlers and magnetosonic perturbations is studied in the present paper. For typical parameters, there is no modulational instability. However, modulational instability appears in special cases. For example, when the whistler wavenumber is small enough, there is modulational instability. Its growth rate decreases as the angle between the external magnetic field and the perturbed wave's direction increases, while it increases as the whistler wavenumber increases. It is also found that there is no modulational instability when the whistler wavenumber is larger than a critical value (<jats:inline-formula> <jats:alternatives> <jats:tex-math>$k_0 &gt; 0.05$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S002237782400014X_inline1.png\" /> </jats:alternatives> </jats:inline-formula>), in which the perturbed wave frequency increases as the angle between the external magnetic field and the perturbed wave's direction increases when the angle between the external magnetic field and the perturbed wave's direction is large enough. Whereas, the perturbed wave frequency first increases as the whistler wavenumber increases, reaches a peak value and then decreases as whistler wavenumber increases.","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"1 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140006685","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":"Accelerating self-modulated nonlinear waves in weakly and strongly magnetized relativistic plasmas","authors":"Felipe A. Asenjo","doi":"10.1017/s0022377824000229","DOIUrl":"https://doi.org/10.1017/s0022377824000229","url":null,"abstract":"It is known that a nonlinear Schrödinger equation describes the self-modulation of a large amplitude circularly polarized wave in relativistic electron–positron plasmas in the weakly and strongly magnetized limits. Here, we show that such an equation can be written as a modified second Painlevé equation, producing accelerated propagating wave solutions for those nonlinear plasmas. This solution even allows the plasma wave to reverse its direction of propagation. The acceleration parameter depends on the plasma magnetization. This accelerating solution is different to the usual soliton solution propagating at constant speed.","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"14 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140006793","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":"Magnetic fields with general omnigenity","authors":"Daniel W. Dudt, Alan G. Goodman, Rory Conlin, Dario Panici, Egemen Kolemen","doi":"10.1017/s0022377824000151","DOIUrl":"https://doi.org/10.1017/s0022377824000151","url":null,"abstract":"Omnigenity is a desirable property of toroidal magnetic fields that ensures confinement of trapped particles. Confining charged particles is a basic requirement for any fusion power plant design, but it can be difficult to satisfy with the non-axisymmetric magnetic fields used by the stellarator approach. Every ideal magnetohydrodynamic equilibrium previously found to approximate omnigenity has been either axisymmetric, quasi-symmetric or has poloidally closed contours of magnetic field strength <jats:inline-formula> <jats:alternatives> <jats:tex-math>$B$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377824000151_inline1.png\" /> </jats:alternatives> </jats:inline-formula>. However, general omnigenous equilibria are a much larger design space than these subsets. A new model is presented and employed in the DESC stellarator optimization suite to represent and discover the full parameter space of omnigenous equilibria. Although exact omnigenity aside from quasi-symmetry is impossible, these results reveal that excellent particle confinement can be achieved in practice. Examples far from quasi-symmetry with poloidally, helically and toroidally closed <jats:inline-formula> <jats:alternatives> <jats:tex-math>$B$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377824000151_inline2.png\" /> </jats:alternatives> </jats:inline-formula> contours are attained with DESC and shown to have low neoclassical collisional transport and fast particle losses.","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"28 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140006799","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":"Confinement of transitioning particles in bi-helical Wendelstein-type configurations","authors":"A.V. Tykhyy, Ya.I. Kolesnichenko","doi":"10.1017/s0022377824000023","DOIUrl":"https://doi.org/10.1017/s0022377824000023","url":null,"abstract":"<p>Recently, stochastic motion of 3.5-MeV alpha particles with orbits that vary between locally trapped and locally passing states (transitioning particles) in a Helias reactor was observed numerically. This validated the theoretical predictions that (i) the stochastic diffusion represents a mechanism of considerable delayed loss of fast ions in quasi-isodynamic stellarators and (ii) it is possible to prevent the escape of particles to the wall by closing the separatrix between the locally trapped and passing states. It was concluded that, in principle, the separatrix could be made closed, resulting in a reduction of fast ion losses, by compensating for the effect of the helical component of the magnetic field <span><span><span data-mathjax-type=\"texmath\"><span>$(1, 1)$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240223170730571-0694:S0022377824000023:S0022377824000023_inline1.png\"/></span></span> with an enhanced ‘anti-helical’ harmonic <span><span><span data-mathjax-type=\"texmath\"><span>$(1, -1)$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240223170730571-0694:S0022377824000023:S0022377824000023_inline2.png\"/></span></span>; the enlargement of this harmonic was proposed previously for other reasons. This possibility is explored in this work. Equations of previous relevant works were generalised to include the <span><span><span data-mathjax-type=\"texmath\"><span>$(1, -1)$</span></span><img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20240223170730571-0694:S0022377824000023:S0022377824000023_inline3.png\"/></span></span> harmonic. Calculations were carried out for several magnitudes of the ratio of anti-helical to helical magnetic field harmonics. Positive effects were found already at the smallest anti-helical harmonic considered: when the latter ratio is 0.25, transitioning particles with the smallest and intermediate pitch parameters are confined and, moreover, their fraction decreased. When the ratio is 0.85, almost all transitioning particles are confined and their fraction is minimal; well-confined localised orbits dominate at the smallest pitch parameters.</p>","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"27 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139967515","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":"Turbulence spreading effects on the ELM size and SOL width","authors":"Nami Li, X.Q. Xu, P.H. Diamond, Y.F. Wang, X. Lin, N. Yan, G.S. Xu","doi":"10.1017/s0022377824000199","DOIUrl":"https://doi.org/10.1017/s0022377824000199","url":null,"abstract":"BOUT++ turbulence simulations were performed to investigate the impact of turbulence spreading on the edge localized mode (ELM) size and divertor heat flux width &lt;jats:inline-formula&gt; &lt;jats:alternatives&gt; &lt;jats:tex-math&gt;$({lambda _q})$&lt;/jats:tex-math&gt; &lt;jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377824000199_inline1.png\" /&gt; &lt;/jats:alternatives&gt; &lt;/jats:inline-formula&gt; broadening in small ELM regimes. This study is motivated by EAST experiments. BOUT++ linear simulations of a pedestal radial electric field (&lt;jats:italic&gt;E&lt;jats:sub&gt;r&lt;/jats:sub&gt;&lt;/jats:italic&gt;) scan show that the dominant toroidal number mode (&lt;jats:italic&gt;n&lt;/jats:italic&gt;) shifts from high-&lt;jats:italic&gt;n&lt;/jats:italic&gt; to low-&lt;jats:italic&gt;n&lt;/jats:italic&gt;, with a narrow mode spectrum, and the maximum linear growth rate increases as the pedestal &lt;jats:italic&gt;E&lt;jats:sub&gt;r&lt;/jats:sub&gt;&lt;/jats:italic&gt; well deepens. The nonlinear simulations show that as the net &lt;jats:italic&gt;E&lt;/jats:italic&gt; × &lt;jats:italic&gt;B&lt;/jats:italic&gt; pedestal flow increases, the pressure fluctuation level and its inward penetration beyond the top of the pedestal both increase. This leads to a transition from small ELMs to large ELMs. Both inward and outward turbulence spreading are sensitive to the scrape-off-layer (SOL) plasma profiles. The inward turbulence spreading increases for the steep SOL profiles, leading to increasing pedestal energy loss in the small ELM regime. The SOL width &lt;jats:inline-formula&gt; &lt;jats:alternatives&gt; &lt;jats:tex-math&gt;$({lambda _q})$&lt;/jats:tex-math&gt; &lt;jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377824000199_inline2.png\" /&gt; &lt;/jats:alternatives&gt; &lt;/jats:inline-formula&gt; is significantly broadened progressing from the ELM-free to small ELM regime, due to the onset of strong radial turbulent transport. The extent of the SOL width &lt;jats:inline-formula&gt; &lt;jats:alternatives&gt; &lt;jats:tex-math&gt;$({lambda _q})$&lt;/jats:tex-math&gt; &lt;jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377824000199_inline3.png\" /&gt; &lt;/jats:alternatives&gt; &lt;/jats:inline-formula&gt; broadening depends strongly on outward turbulence spreading. The fluctuation energy intensity flux &lt;jats:inline-formula&gt; &lt;jats:alternatives&gt; &lt;jats:tex-math&gt;${varGamma _varepsilon }$&lt;/jats:tex-math&gt; &lt;jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377824000199_inline4.png\" /&gt; &lt;/jats:alternatives&gt; &lt;/jats:inline-formula&gt; at the separatrix can be enhanced by increasing either pedestal &lt;jats:italic&gt;E&lt;jats:sub&gt;r&lt;/jats:sub&gt;&lt;/jats:italic&gt; flow shear or local SOL pressure gradient. The &lt;jats:inline-formula&gt; &lt;jats:alternatives&gt; &lt;jats:tex-math&gt;${lambda _q}$&lt;/jats:tex-math&gt; &lt;jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0022377824000199_inline5.png\" /&gt; &lt;/jats:alternatives&gt; &lt;/jats:inline-formula&gt; is broadened as the fluctuation ene","PeriodicalId":16846,"journal":{"name":"Journal of Plasma Physics","volume":"1 1","pages":""},"PeriodicalIF":2.5,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139955888","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}