学术报告第153期—吴菲阳 唐畴尧 唐畴尧论文投稿报告

时间：2021年11月24日  周三  14:30

地点：326会议室

论文投稿报告

报告人：吴菲阳 研究生

题目：Design and Implement of Control System for HUST Field-Reversed Configuration Device

摘要：

HFRC (HUST Field-Reversed Configuration) device is a complex magnetic confinement fusion research device for studying field-reversed configuration, which is composed of many different subsystems.Compared to Tokamak, HFRC has fewer and simpler subsystems, but raises higher requirements for the flexibility in process control due to the frequent change of the discharge process because it is still under development.

This paper presents a design and implement of the web based HFRC control system, which can orchestrate all the instruments and devices to conduct a successful experiment, as well as collect and archive the scientific data generated during the experiments. HFRC control system adopts the modularized and micro service architecture. The whole system is built as a suite of small services, each running in its own process and is independently deployable. It also adopts the Observer and FSM patterns, which work well in controlling the flow of discharging and handle exceptions. The in-house developed CFET (Control system Framework for Experimental Devices Toolkit) has been selected as the control framework instead of EPICS toolkit, because of its advantages such as simplified framework, transparent protocol, flexible extension. HFRC Control System offers a customizable web based HMI allowing users to design the HMI by simply dragging and dropping widgets in the browser.

HFRC Control System has been initially deployed in daily experiments of HFRC. Moreover, the studies on emerging technologies will provide valuable experiences for future control system design of fusion device.

报告人：唐畴尧 研究生

题目：Real-time measurement of plasma horizontal displacement for J-TEXT based on neural networks

摘要：

Plasma displacement measurement is one of the basic diagnostic tools for evaluating the plasma operating state in a tokamak device. In general, plasma displacement refers to the displacement of the plasma current center. This information can be quickly obtained by equilibrium inversion and then used in the plasma feedback control system. The data needed for inversion comes from the magnetic probe. However, the magnetic flux generated by certain coils can disturb the displacement probe, such as Resonant Magnetic Perturbation (RMP). This paper proposes to use a neural network to design a non-magnetic real-time measurement method of plasma horizontal displacement.

The main content of this paper is divided into two aspects. On the one hand, a fully-connected neural network model is trained. The model is augmented by a special means to reduce the overfitting and improve the robustness. A satisfactory fitting effect is obtained. On the other hand, to apply the neural network to the plasma feedback control system, a real-time application based on J-TEXT Real-Time Framework(JRTF) is quickly developed to deploy the neural network. The actual test results show that this non-magnetic real-time displacement measurement system can calculate the plasma horizontal displacement during the flat-top phase of the J-TEXT plasma discharges.

报告人：黄章盛 研究生

题目：The synergetic effects of three-dimensional magnetic perturbations and finite beta on collisionless trapped electron mode in tokamak plasmas

摘要：

The effects of three-dimensional (3D) magnetic perturbations (MPs) and finite (the ratio of plasma kinetic pressure to magnetic pressure) on the instability of collisionless trapped electron mode (CTEM) have been studied. We have derived a general expression for longitudinal invariant and the corresponding precession drift frequency of trapped electrons, which includes the synergetic effects of MPs and finite. Based on the analytical solution of the dispersion equation of CTEM instability, it is found that 3D effects can either stabilize or destabilize CTEM instability. This depends on the poloidal and toroidal mode numbers as well as the phase of 3D MPs. Specially, for the destabilizing phase of MPs, the stabilizing effect of finite on CTEM [Connor, J. W. et al., Nuclear Fusion 23, 032561 (1978)] can be even reversed when the displacement of magnetic surface exceeds a critical value. Moreover, the synergetic effects of 3D MPs and finite can further reduce the required absolute value of negative magnetic shear to completely stabilize CTEM instability for the stabilizing phase of MPs. This indicates that 3D MPs might be used as an actuator for lowing the level of anomalous electron heat transport, and thus facilitate the formation of electron internal transport barrier (eITB).