Construction and Preliminary Results of Huazhong Field Reversed Configuration Device

Summary

This document introduces the construction and preliminary experimental results of the Huazhong Field Reversed Configuration (HFRC) device at Huazhong University of Science and Technology. It outlines the research focus on FRC formation optimization, magnetic compression, and instability control, utilizing multi-channel optical fiber interferometry and UV photodiode diagnostics to monitor plasma evolution.

Title and Author Information

Bo Rao¹, Ming Zhang¹, Yong Yang¹, Zhipeng Chen¹, Wei Zheng¹, Zhijiang Wang¹, Li Gao¹, Zhifeng Cheng¹, Xuan Sun², Wei Jiang³, Yonghua Ding¹, Kexun Yu¹, Yuan Pan¹

¹ International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics (IFPP), State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China ² Department of Plasma Physics and Fusion Engineering, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, People’s Republic of China ³ School of Physics, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China

Introduction and HFRC Device Overview

Field reversed configuration (FRC), first been discovered in theta pinch plasma researches in 1960s, has now gained more and more attention for its several advantages [1-3]. In the past two or three decades, many people begin to explore new methods to obtain nuclear fusion energy in a simpler and cheaper way. Because FRC has a very high beta (ratio of plasma thermal pressure and magnetic pressure), and relatively good plasma confinement performance, it is usually considered as a steady plasma carrier or a target for compression. FRC is taken as basic magnetic configuration and driven by neutral beams, and has set new record of plasma lifetime and reached 30ms in C-2 series devices [4-5]. FRC is also adopted as initial target for solid liner compression (known as magnetized target fusion (MTF) [6] or magneto-inertia fusion [7]), magnetic compression [8], and plasma jet compression (known as plasma jet magnetic inertia fusion (PJMIF) [9]). FRC is now even being considered as initial target plasma in Z pinch [10].

A large field reversed configuration (FRC) research device named as HFRC has been constructed in Huazhong University of Science and Technology (HUST) in Wuhan. In HFRC, on optimization of FRC formation methods and magnetic compression will be mainly focused. Multi-coil field reversed theta pinch is usually adopted to form and accelerate the FRC [5]. In this method, proper and accurate sequential coordination is a crucial issue for a high performance FRC. On HFRC, an axial multi-channel optical fiber interferometer has been equipped in the formation region to measure the electron density evolution during the fast FRC formation process. Besides, a photodiode array for detecting 200nm ~ 400nm ultra-violet emission from core region is also used to optimize the time coordination of the pulsed power supply. Preliminary results of the density evolution during the dynamic formation and its impacts on formed FRC will be given in the conference.

Magnetic Compression and Instability Control

Compression is thought very useful to improve plasma temperature and density substantially. Among typical plasma compression methods, magnetic compression has several advantages. The compression magnetic field is generated by external coils and current, which can easily be controlled accurately, and make magnetic compression more repeatable and controllable. The limited strength and rising rate of the compression field and interchange instabilities are main challenges. On HFRC, new method of controlling instabilities will be investigated.

Figure 1 Photo of a HFRC discharge

Reference

[1] Tuszewski M 1988 Nucl. Fusion 28 2033 [2] Steinhauer L C 2011 Phys. Plasmas 18 070501 [3] Liao H 2022 Plasma Sci. Technol. 24 095103 [4] Guo H Y et al. 2015 Nature Communications 6 6897 [5] Gota H et al 2021 Nucl. Fusion 61 106039 [6] Barnes D C 1997 Comments on Plasma Physics and Controlled Fusion 18 71 [7] Degnan J H et al 2013 Nucl. Fusion 53 093003 [8] Slough J, Votroubek G and Pih C 2011 Nucl. Fusion 51 053008 [9] Francis Thio Y C et al 2019 Fusion Science and Technology 75 581 [10] Brendan Sporer Z Fundamental Science Program Workshop, 03-05 August 2022