Whistler waves have been studied for many years in relation to turbulence and particle heating, and observations show that they are crucial to magnetic reconnection. Recent research has revealed a close relationship between magnetic reconnection and turbulence. The current work investigates the whistler turbulence caused by the energetic electron beam in the magnetic reconnection sites of magnetopause and also due to dynamic evolution of magnetic islands. For this, we develop a model based upon the two-fluid approximation to study whistler dynamics, propagating in the medium with the pre-existing chain of magnetic islands and under the influence of background density perturbation originating from ponderomotive nonlinearity of wave. Dynamics of nonlinear whistler have been solved with pseudo-spectral approach and a finite difference method with a modified predictor–corrector method and a Runge Kutta method for the semianalytical model. In the current research, we study how the nonlinear whistler wave contributes to the significant space phenomenon, i.e., turbulence, localization, and magnetic reconnection. We have also investigated the formation of a current sheet in a magnetopause region of the order of few-electron inertial length. We analyzed the power spectrum at the magnetopause when the system reached a quasi-steady condition. Our new approach to study whistler turbulence by an energetic electron beam at the magnetic reconnection sites has extensive applications to space plasmas, shedding a new light on the study of magnetic reconnection in nature.
{"title":"Localization of beam generated whistler wave and turbulence generation in reconnection region of magnetopause","authors":"Jyoti, Suresh C. Sharma, R. P. Sharma","doi":"10.1063/5.0169397","DOIUrl":"https://doi.org/10.1063/5.0169397","url":null,"abstract":"Whistler waves have been studied for many years in relation to turbulence and particle heating, and observations show that they are crucial to magnetic reconnection. Recent research has revealed a close relationship between magnetic reconnection and turbulence. The current work investigates the whistler turbulence caused by the energetic electron beam in the magnetic reconnection sites of magnetopause and also due to dynamic evolution of magnetic islands. For this, we develop a model based upon the two-fluid approximation to study whistler dynamics, propagating in the medium with the pre-existing chain of magnetic islands and under the influence of background density perturbation originating from ponderomotive nonlinearity of wave. Dynamics of nonlinear whistler have been solved with pseudo-spectral approach and a finite difference method with a modified predictor–corrector method and a Runge Kutta method for the semianalytical model. In the current research, we study how the nonlinear whistler wave contributes to the significant space phenomenon, i.e., turbulence, localization, and magnetic reconnection. We have also investigated the formation of a current sheet in a magnetopause region of the order of few-electron inertial length. We analyzed the power spectrum at the magnetopause when the system reached a quasi-steady condition. Our new approach to study whistler turbulence by an energetic electron beam at the magnetic reconnection sites has extensive applications to space plasmas, shedding a new light on the study of magnetic reconnection in nature.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"189 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139821512","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}
R. Perillo, J. Boedo, C. Lasnier, A. McLean, I. Bykov, C. Marini, D. Rudakov, J. Watkins
Small/type-II edge-localized-modes (ELMs), carrying 1% of the plasma stored energy, are found to deposit only 45 ± 5% of the ELM power near the strike point, and the remaining 55 ± 5% to the far scrape-off-layer (SOL). Small ELMs spread their power over a larger area compared to type-I ELMs, where such a ratio is about 60% and 40% for near- and far-SOL regions, respectively. The larger spread is reflected in the heat flux width (λq) in the SOL for the intra-small ELMs profile of 6.0 mm, almost a factor 2 larger than that of type-I ELMs of 3.15 mm, for similar plasma conditions and magnetic configuration. At the ELM peak, the small ELMs λq is found to be up to 4 times larger than for the type-I ELMs, going from 2 to 7.9 mm, indicating enhanced radial transport in the neon-seeded small ELM scenario. Inter-ELM λqs have been also calculated at the secondary outer divertor in quasi-double-null (QDN) discharges. It is found that, on average, λq is 2.2 times larger in the high-separatrix-density small ELM regime, compared to a reference type-I ELM one. These findings are supported by small ELMs radial velocity profiles, measured at the outer midplane with a fast reciprocating probe, showing a decay length (λvr) in the SOL of 12.8 cm, which is 3.3 times larger than that for the type-I ELMs of 3.9 cm. This analysis shows that small ELMs, although attractive for future machines due to low peak heat flux and large λq, might be of concern for the larger flux to the outer wall.
研究发现，携带 1%等离子体存储能量的小型/II 型边缘定位模式（ELM）仅将 45 ± 5% 的 ELM 功率沉积在撞击点附近，其余 55 ± 5% 的功率沉积在远刮擦层（SOL）。与 I 型电致发光器相比，小型电致发光器的功率分布面积更大，在近 SOL 和远 SOL 区域，这一比例分别约为 60% 和 40%。在类似等离子体条件和磁场配置下，小型ELM内部剖面在SOL中的热通量宽度（λq）为6.0毫米，几乎比I型ELM的3.15毫米大2倍。在ELM峰值，小型ELM的λq比I型ELM的λq大4倍，从2毫米到7.9毫米，表明在氖种子小型ELM情况下径向传输增强。在准双空（QDN）放电中，还计算了次级外分流器的 ELM 间 λq。结果发现，与参考的 I 型 ELM 相比，在高分离基质密度的小型 ELM 系统中，λq 平均要大 2.2 倍。用快速往复探头在外侧中平面测量的小型 ELM 径向速度剖面图支持了这些发现，该剖面图显示 SOL 的衰减长度（λvr）为 12.8 厘米，比 I 型 ELM 的 3.9 厘米大 3.3 倍。这一分析表明，虽然小型 ELM 因峰值热通量低和 λq 大而对未来的机器具有吸引力，但可能会因外壁的通量较大而引起关注。
{"title":"Experimental evidence of enhanced radial transport in small ELM regimes at DIII-D","authors":"R. Perillo, J. Boedo, C. Lasnier, A. McLean, I. Bykov, C. Marini, D. Rudakov, J. Watkins","doi":"10.1063/5.0181309","DOIUrl":"https://doi.org/10.1063/5.0181309","url":null,"abstract":"Small/type-II edge-localized-modes (ELMs), carrying 1% of the plasma stored energy, are found to deposit only 45 ± 5% of the ELM power near the strike point, and the remaining 55 ± 5% to the far scrape-off-layer (SOL). Small ELMs spread their power over a larger area compared to type-I ELMs, where such a ratio is about 60% and 40% for near- and far-SOL regions, respectively. The larger spread is reflected in the heat flux width (λq) in the SOL for the intra-small ELMs profile of 6.0 mm, almost a factor 2 larger than that of type-I ELMs of 3.15 mm, for similar plasma conditions and magnetic configuration. At the ELM peak, the small ELMs λq is found to be up to 4 times larger than for the type-I ELMs, going from 2 to 7.9 mm, indicating enhanced radial transport in the neon-seeded small ELM scenario. Inter-ELM λqs have been also calculated at the secondary outer divertor in quasi-double-null (QDN) discharges. It is found that, on average, λq is 2.2 times larger in the high-separatrix-density small ELM regime, compared to a reference type-I ELM one. These findings are supported by small ELMs radial velocity profiles, measured at the outer midplane with a fast reciprocating probe, showing a decay length (λvr) in the SOL of 12.8 cm, which is 3.3 times larger than that for the type-I ELMs of 3.9 cm. This analysis shows that small ELMs, although attractive for future machines due to low peak heat flux and large λq, might be of concern for the larger flux to the outer wall.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"5 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139873780","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}
D. Silvagni, M. Dunne, T. Luda, A. Bock, A. Burckhart, R. Fischer, M. Griener, R. M. McDermott, U. Plank, T. Pütterich, M. Reisner, J. Stober, B. Tal, G. Tardini, H. Zohm
Over previous campaigns, an intense experimental program on advanced tokamak (AT) scenarios, has been carried out at the ASDEX Upgrade tokamak with full-tungsten wall. These discharges have been executed shortly after the boronization of the first wall to reduce the density and the impurity influx. The confinement level of such AT discharges was found to vary considerably, even when discharges with similar, if not identical, engineering parameters were carried out. This work investigates the causes of such confinement variations. Among all plasma quantities analyzed, confinement quality of AT scenarios correlates best with divertor neutral pressure, highlighting the key role of edge and scrape-off layer physics in determining global plasma confinement. In particular, it is found that the main cause of confinement degradation is the reduction of pedestal stability, which is in turn caused by the outward shift of the maximum density gradient position typically observed when the divertor neutral pressure increases. Owing to the low density of AT discharges under analysis, the movement of the maximum density gradient position can be caused entirely by changes in deuterium outgassing from the wall, which is strongly influenced by the boron layer deposited on the plasma-facing components and by the deuterium wall inventory. Finally, the predictive capability of confinement quality with the integrated model IMEP [Luda et al., Nucl. Fusion 60, 036023 (2020)] is tested on these discharges and shows promising results.
在以往的活动中，ASDEX 升级版全钨壁托卡马克已经开展了一项针对先进托卡马克（AT）方案的密集实验计划。这些放电是在第一壁硼化后不久进行的，目的是降低密度和杂质流入。研究发现，即使在工程参数相似（甚至不完全相同）的情况下进行放电，这种 AT 放电的约束水平也会有很大差异。这项工作研究了造成这种约束变化的原因。在分析的所有等离子体量中，AT 方案的束缚质量与分流器中性压力的相关性最好，突出了边缘和刮除层物理在决定全局等离子体束缚中的关键作用。特别是，研究发现，约束性下降的主要原因是基座稳定性的降低，而基座稳定性的降低又是由最大密度梯度位置的外移造成的，而最大密度梯度位置的外移通常是在分流器中性压力增加时观察到的。由于所分析的 AT 放电密度较低，最大密度梯度位置的移动可能完全是由壁面氘排出量的变化引起的，而氘排出量受沉积在面向等离子体部件上的硼层和壁面氘存量的影响很大。最后，利用综合模型 IMEP [Luda 等人，Nucl. Fusion 60, 036023 (2020)]对约束质量的预测能力在这些放电中进行了测试，结果很有希望。
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Whistler waves have been studied for many years in relation to turbulence and particle heating, and observations show that they are crucial to magnetic reconnection. Recent research has revealed a close relationship between magnetic reconnection and turbulence. The current work investigates the whistler turbulence caused by the energetic electron beam in the magnetic reconnection sites of magnetopause and also due to dynamic evolution of magnetic islands. For this, we develop a model based upon the two-fluid approximation to study whistler dynamics, propagating in the medium with the pre-existing chain of magnetic islands and under the influence of background density perturbation originating from ponderomotive nonlinearity of wave. Dynamics of nonlinear whistler have been solved with pseudo-spectral approach and a finite difference method with a modified predictor–corrector method and a Runge Kutta method for the semianalytical model. In the current research, we study how the nonlinear whistler wave contributes to the significant space phenomenon, i.e., turbulence, localization, and magnetic reconnection. We have also investigated the formation of a current sheet in a magnetopause region of the order of few-electron inertial length. We analyzed the power spectrum at the magnetopause when the system reached a quasi-steady condition. Our new approach to study whistler turbulence by an energetic electron beam at the magnetic reconnection sites has extensive applications to space plasmas, shedding a new light on the study of magnetic reconnection in nature.
{"title":"Localization of beam generated whistler wave and turbulence generation in reconnection region of magnetopause","authors":"Jyoti, Suresh C. Sharma, R. P. Sharma","doi":"10.1063/5.0169397","DOIUrl":"https://doi.org/10.1063/5.0169397","url":null,"abstract":"Whistler waves have been studied for many years in relation to turbulence and particle heating, and observations show that they are crucial to magnetic reconnection. Recent research has revealed a close relationship between magnetic reconnection and turbulence. The current work investigates the whistler turbulence caused by the energetic electron beam in the magnetic reconnection sites of magnetopause and also due to dynamic evolution of magnetic islands. For this, we develop a model based upon the two-fluid approximation to study whistler dynamics, propagating in the medium with the pre-existing chain of magnetic islands and under the influence of background density perturbation originating from ponderomotive nonlinearity of wave. Dynamics of nonlinear whistler have been solved with pseudo-spectral approach and a finite difference method with a modified predictor–corrector method and a Runge Kutta method for the semianalytical model. In the current research, we study how the nonlinear whistler wave contributes to the significant space phenomenon, i.e., turbulence, localization, and magnetic reconnection. We have also investigated the formation of a current sheet in a magnetopause region of the order of few-electron inertial length. We analyzed the power spectrum at the magnetopause when the system reached a quasi-steady condition. Our new approach to study whistler turbulence by an energetic electron beam at the magnetic reconnection sites has extensive applications to space plasmas, shedding a new light on the study of magnetic reconnection in nature.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"19 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139881242","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}
R. Perillo, J. Boedo, C. Lasnier, A. McLean, I. Bykov, C. Marini, D. Rudakov, J. Watkins
Small/type-II edge-localized-modes (ELMs), carrying 1% of the plasma stored energy, are found to deposit only 45 ± 5% of the ELM power near the strike point, and the remaining 55 ± 5% to the far scrape-off-layer (SOL). Small ELMs spread their power over a larger area compared to type-I ELMs, where such a ratio is about 60% and 40% for near- and far-SOL regions, respectively. The larger spread is reflected in the heat flux width (λq) in the SOL for the intra-small ELMs profile of 6.0 mm, almost a factor 2 larger than that of type-I ELMs of 3.15 mm, for similar plasma conditions and magnetic configuration. At the ELM peak, the small ELMs λq is found to be up to 4 times larger than for the type-I ELMs, going from 2 to 7.9 mm, indicating enhanced radial transport in the neon-seeded small ELM scenario. Inter-ELM λqs have been also calculated at the secondary outer divertor in quasi-double-null (QDN) discharges. It is found that, on average, λq is 2.2 times larger in the high-separatrix-density small ELM regime, compared to a reference type-I ELM one. These findings are supported by small ELMs radial velocity profiles, measured at the outer midplane with a fast reciprocating probe, showing a decay length (λvr) in the SOL of 12.8 cm, which is 3.3 times larger than that for the type-I ELMs of 3.9 cm. This analysis shows that small ELMs, although attractive for future machines due to low peak heat flux and large λq, might be of concern for the larger flux to the outer wall.
研究发现，携带 1%等离子体存储能量的小型/II 型边缘定位模式（ELM）仅将 45 ± 5% 的 ELM 功率沉积在撞击点附近，其余 55 ± 5% 的功率沉积在远刮擦层（SOL）。与 I 型电致发光器相比，小型电致发光器的功率分布面积更大，在近 SOL 和远 SOL 区域，这一比例分别约为 60% 和 40%。在类似等离子体条件和磁场配置下，小型ELM内部剖面在SOL中的热通量宽度（λq）为6.0毫米，几乎比I型ELM的3.15毫米大2倍。在ELM峰值，小型ELM的λq比I型ELM的λq大4倍，从2毫米到7.9毫米，表明在氖种子小型ELM情况下径向传输增强。在准双空（QDN）放电中，还计算了次级外分流器的 ELM 间 λq。结果发现，与参考的 I 型 ELM 相比，在高分离基质密度的小型 ELM 系统中，λq 平均要大 2.2 倍。用快速往复探头在外侧中平面测量的小型 ELM 径向速度剖面图支持了这些发现，该剖面图显示 SOL 的衰减长度（λvr）为 12.8 厘米，比 I 型 ELM 的 3.9 厘米大 3.3 倍。这一分析表明，虽然小型 ELM 因峰值热通量低和 λq 大而对未来的机器具有吸引力，但可能会因外壁的通量较大而引起关注。
{"title":"Experimental evidence of enhanced radial transport in small ELM regimes at DIII-D","authors":"R. Perillo, J. Boedo, C. Lasnier, A. McLean, I. Bykov, C. Marini, D. Rudakov, J. Watkins","doi":"10.1063/5.0181309","DOIUrl":"https://doi.org/10.1063/5.0181309","url":null,"abstract":"Small/type-II edge-localized-modes (ELMs), carrying 1% of the plasma stored energy, are found to deposit only 45 ± 5% of the ELM power near the strike point, and the remaining 55 ± 5% to the far scrape-off-layer (SOL). Small ELMs spread their power over a larger area compared to type-I ELMs, where such a ratio is about 60% and 40% for near- and far-SOL regions, respectively. The larger spread is reflected in the heat flux width (λq) in the SOL for the intra-small ELMs profile of 6.0 mm, almost a factor 2 larger than that of type-I ELMs of 3.15 mm, for similar plasma conditions and magnetic configuration. At the ELM peak, the small ELMs λq is found to be up to 4 times larger than for the type-I ELMs, going from 2 to 7.9 mm, indicating enhanced radial transport in the neon-seeded small ELM scenario. Inter-ELM λqs have been also calculated at the secondary outer divertor in quasi-double-null (QDN) discharges. It is found that, on average, λq is 2.2 times larger in the high-separatrix-density small ELM regime, compared to a reference type-I ELM one. These findings are supported by small ELMs radial velocity profiles, measured at the outer midplane with a fast reciprocating probe, showing a decay length (λvr) in the SOL of 12.8 cm, which is 3.3 times larger than that for the type-I ELMs of 3.9 cm. This analysis shows that small ELMs, although attractive for future machines due to low peak heat flux and large λq, might be of concern for the larger flux to the outer wall.","PeriodicalId":510396,"journal":{"name":"Physics of Plasmas","volume":"56 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139814001","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}
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