Comparative experiments of co- and counter-helicity merging in the compact toroid merging device TS-4

Tsuruda, Mayuko; Ono, Yasushi; Katsurai, Makoto

doi:10.1541/ieejfms.122.840

Cited by 7 publications

(3 citation statements)

References 9 publications

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“…The plasma guns can create left- or right-handed spheromaks by switching the polarity on the stuffing field magnet, and so the polarity of the poloidal magnetic field, allowing the study of same helicity or opposite helicity merging flux tubes (see, e.g., Yamada et al. 1997; Tsuruda, Ono & Katsurai 2002).…”

Section: Understanding the Onset Problem: A Common Goal Of Astrophysimentioning

confidence: 99%

“…Once generated at the ends of a vacuum chamber, the two opposite magnetic field polarity spheromaks can be translated in to the region in the centre where the experiment takes place (Yamada et al 1997;Kornack 2001). The plasma guns can create left-or right-handed spheromaks by switching the polarity on the stuffing field magnet, and so the polarity of the poloidal magnetic field, allowing the study of same helicity or opposite helicity merging flux tubes (see, e.g., Yamada et al 1997;Tsuruda, Ono & Katsurai 2002).…”

Section: Reconnection In Laboratory Plasmas: Mrx and Merging Spheromaksmentioning

confidence: 99%

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Onset of fast magnetic reconnection and particle energization in laboratory and space plasmas

et al. 2020

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The onset of magnetic reconnection in space, astrophysical and laboratory plasmas is reviewed discussing results from theory, numerical simulations and observations. After a brief introduction on magnetic reconnection and approach to the question of onset, we first discuss recent theoretical models and numerical simulations, followed by observations of reconnection and its effects in space and astrophysical plasmas from satellites and ground-based detectors, as well as measurements of reconnection in laboratory plasma experiments. Mechanisms allowing reconnection spanning from collisional resistivity to kinetic effects as well as partial ionization are described, providing a description valid over a wide range of plasma parameters, and therefore applicable in principle to many different astrophysical and laboratory environments. Finally, we summarize the implications of reconnection onset physics for plasma dynamics throughout the Universe and illustrate how capturing the dynamics correctly is important to understanding particle acceleration. The goal of this review is to give a view on the present status of this topic and future interesting investigations, offering a unified approach.

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Section: Understanding the Onset Problem: A Common Goal Of Astrophysimentioning

confidence: 99%

Section: Reconnection In Laboratory Plasmas: Mrx and Merging Spheromaksmentioning

confidence: 99%

Onset of fast magnetic reconnection and particle energization in laboratory and space plasmas

et al. 2020

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“…Thus, the RFP in the TS-4 device will be referred to as a compact RFP here. The details of the TS-4 device are explained elsewhere [4,5].…”

Section: Experimental Apparatusmentioning

confidence: 99%

Comparative studies on magnetic flux relaxations of varied spherical toroids produced by co‐helicity merging

Tsuruda

Ono

Katsurai

2005

Electrical Engineering Japan

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SUMMARYThe co-helicity merging operations of compact toroid (CT) and spherical tokamak (ST) have been performed with external toroidal fields in the CT/ST merging device TS-4. The low-q (safety factor) CT merging as the compact RFP merging and the spheromak merging show the flux conversion from toroidal to poloidal in the course of the reconstruction of the Taylor force free state. The relaxation to the Taylor state proceeds through the following three states: (1) axisymmetric merging with increasing toroidal flux; (2) increase in the poloidal flux Ψ; and (3) relaxation to the Taylor state. The high-q ST merging shows different relaxation process from those of the compact RFP and the spheromak mergings. Increases in Ψ were not clearly observed in the ST merging. The measured eigenvalues λ show that ST's, especially high-q ST's, approach a unique intrinsic equilibrium state that has a λ proportional to Ψ with a longer lifetime than that of CT's. When external toroidal field is set in a certain range between the low-q operation and the high-q operation for ST's, an abnormal phenomenon was found in the ST formation, namely, a drastic decrease in the plasma lifetime. This phenomenon is characterized by very weak poloidal flux generations during the initial plasma production phase and the subsequent plasma separation phase when the plasma starts detaching from the flux core.

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Influence of Non-Axisymmetric n=1 Toroidal Mode Instabilities on Reconstruction Measurements of Magnetic Surfaces for Compact Torus Plasmas

Tsuruda

Katsurai

2003

IEEJ Trans. FM

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The influence of non-axisymmetric instabilities, specifically the n=1 toroidal mode, was studied on the magnetic flux contours that are numerically reconstructed by use of magnetic field profiles measured in Proto-TS-4 device. The device has a cylindrical vacuum vessel with a couple of coaxial magnetized plasma guns at both ends and a magnetic flux conserver with a side axial length of 600mm and a diameter of 940mm. The main measurement system consists of a 2-dimensional magnetic probe array on the poloidal plane(r-z plane) with two components, B z and B t (total 84 channel pickup coils). The B z field data are used to reconstruct the poloidal magnetic surfaces(Ψ) on the assumption that plasma configuration has axisymmetry. In this study, deformation of the reconstructed flux contours has been studied particularly when the plasma configurations were subjected to a macroscopic instability, specifically n=1 toroidal mode instability. The influence of this component on the reconstructed contours was analytically calculated and the results were qualitatively compared with the contours experimentally observed. Types of n=1 error, namely, shift or tilt, on the reconstructed magnetic surface were also qualitatively discussed.

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Comparative experiments of co- and counter-helicity merging in the compact toroid merging device TS-4

Cited by 7 publications

References 9 publications

Onset of fast magnetic reconnection and particle energization in laboratory and space plasmas

Onset of fast magnetic reconnection and particle energization in laboratory and space plasmas

Comparative studies on magnetic flux relaxations of varied spherical toroids produced by co‐helicity merging

Influence of Non-Axisymmetric n=1 Toroidal Mode Instabilities on Reconstruction Measurements of Magnetic Surfaces for Compact Torus Plasmas

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