An analysis of experimental data from the RFX (Reversed Field eXperiment) reversed field pinch machine [L. Fellin, P. Kusstatscher and G. Rostagni, Fusion Eng. Des. {\bf 25}, 315 (1995)] is carried out to investigate the possible existence of deterministic chaos in the edge plasma region. The mathematical tools used include Lyapunov exponents, Kaplan-Yorke dimension, minimum embedding dimension estimates and nonlinear forecasting. The whole analysis agrees in ruling out the possibility of low-dimensional chaos: The dimension of the underlying dynamical system is estimated to be $ > 10$. From a critical re-reading of the literature it emerges that the findings of this work are likely to be common to all reversed field pinches.
A recent study [1] about the scaling with the aspect ratio (i.e. the ratio between the major and minor radius of the torus) of the dominant mode in Single Helical (SH) Reverse Field Pinch (RFP) plasmas has shown, at intermediate aspect ratio, that the dominant toroidal mode number in the helical states can be interpreted as the result of a relaxation process. In this work, the theoretical model is compared and validated with the experimental data obtained in the low aspect ratio RELAX device [2]. [1] R. Paccagnella, Phys. of Plasmas 23 (2016) 092512. [2] S. Masamune et al, J. Phys. Soc. Japan …
Two-fluid boundary turbulence simulations in reversed field pinch plasmas
University of Padua（帕多瓦大学）；Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA)（RFX联盟（意大利国家研究委员会、国家新能源研究中心、意大利国家核物理研究所、帕多瓦大学、威尼斯钢铁公司））；Istituto per la Scienza e la Tecnologia dei Plasmi (ISTP), CNR（等离子体科学与技术研究所，意大利国家研究委员会）
The drift wave in the presence of impurity ions was investigated numerically in reversed field pinch (RFP) plasmas, using the gyrokinetic integral eigenmode equation. It was found that in RFP plasmas with hollow density profiles, an increase in $k_θρ_s$ increases the growth rate of the ion temperature gradient (ITG). Comparing the results of regular and hollow plasma density profile shows that the ITG mode under the hollow density profile is much harder to be excited. For the impurities' effects, when the impurities' density gradient is opposite to the primary ions, namely when $L_{ez}$ is neg…
The Multi-region Relaxed MHD (MRxMHD) has been successful in the construction of equilibria in three-dimensional (3D) configurations. In MRxMHD, the plasma is sliced into sub-volumes separated by ideal interfaces, each undergoing relaxation, allowing the formation of islands and chaos. The resulting equilibrium has a stepped pressure profile across sub-volumes. The Stepped Pressure Equilibrium Code (SPEC) [S.R. Hudson et al., Phys. Plasmas 19, 112502 (2012)] was developed to calculate MRxMHD equilibria numerically. In this work, we have extended the SPEC code to compute MRxMHD equilibria with …
Modelling of impurity heating during reconnections in a Reverse Field Pinch device as due to parallel electric field acceleration and chaos-induced thermalization
本文利用TRB流体静电湍流程序研究了RFX-mod反向场箍缩（Reversed Field Pinch，RFP）准单螺旋区离子温度梯度漂移湍流的稳定性。我们的研究结果表明，目前的RFP等离子体对这种湍流是勉强稳定的。的不稳定性的发病可能会设想为密切的未来制度，在存在更热的等离子体与尖锐的内部传输障碍。
现今的反向场箍缩（Reversed Field Pinches，RFPs）的特征是其核心的准层状磁结构，其边界具有尖锐的内部输运势垒，类似于托卡马克和仿星器。磁混沌的减弱导致伴随粒子和热沿漂移磁力线输运的减少。同时，陡峭的温度梯度的增长可能触发漂移微不稳定性。在这项工作中，我们总结了最近在RFP RFX-mod中所做的工作，以评估离子温度梯度（ITG），陷阱电子模式（TEM）和微撕裂模式等静电和电磁微不稳定性的存在和对运输的影响。
Updated electrical design of the Diagnostic Neutral Beam Injector in RFX-mod2
CNR, Istituto per la Scienza e la Tecnologia dei Plasmi (ISTP)（意大利国家研究委员会等离子体科学与技术研究所）；Consorzio RFX（RFX联盟）；Università di Padova（帕多瓦大学）；Università degli Studi di Padova, Centro Ricerche Fusione (CRF)（帕多瓦大学聚变研究中心）
Programmable control of the inductive electric field enables advanced operations of reversed-field pinch (RFP) plasmas in the Madison Symmetric Torus (MST) device and further develops the technical basis for ohmically heated fusion RFP plasmas. MST's poloidal and toroidal magnetic fields ($B_\text{p}$ and $B_\text{t}$) can be sourced by programmable power supplies (PPSs) based on integrated-gate bipolar transistors (IGBT). In order to provide real-time simultaneous control of both $B_\text{p}$ and $B_\text{t}$ circuits, a time-independent integrated model is developed. The actuators considered…
