Study of Kinetic Parameters of Globus-M Plasma by Thomson Scattering Using an Advanced Digital Polychromator


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Abstract

The local measurements of electron density and temperature by Thomson scattering (TS) diagnostics are essential for research of energy confinement, plasma heating, and control at nuclear fusion devices. This paper presents a digital filter polychromator designed for TS spectrum registration. A distinguishing feature of such a digital polychromator is the use of an analog-to-digital converter (ADC) having analog memory with discretization frequency of 5 GHz and 12-bit sampling. The low heat dissipation and compact design of the ADC allow us to integrate the recording and data handling systems in the spectral unit to obtain a standalone device that is totally isolated from other systems and equipment in the voltaic sense. The scattered laser radiation received from the plasma comes to the entrance of the polychromator through a fiber-optic cable, and the processed scattering signals and calculated electron density and temperature are available on a digital interface. The polychromator was tested within the Thomson scattering system at the Globus-M tokamak using two probing lasers: Nd:YAG 1064 nm and Nd:Glass 1055 nm operating with pulse energy up to 2J and FWHM of 4 and 40 ns, respectively. The employed ADCs allowed us to perform superfast signal digitizing in the oscilloscope mode and to demonstrate the possibility of stray signal time separation despite the modest size (~1 m) of the vacuum chamber. The results of measurements performed during the plasma experiment at the Globus-M tokamak are presented, and their comparative analysis with the data obtained at the operating TS system is made.

About the authors

V. V. Solokha

Ioffe Physical-Technical Institute; Peter the Great St. Petersburg Polytechnic University

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021; St. Petersburg, 195251

A. N. Koval

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

A. E. Litvinov

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

S. V. Masyukevich

SpectralTech Ltd.

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194223

A. G. Razdobarin

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

D. S. Samsonov

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

V. V. Semenov

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

V. A. Solovey

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

P. V. Chernakov

SpectralTech Ltd.

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194223

Al. P. Chernakov

SpectralTech Ltd.

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194223

M. M. Kochergin

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

A. M. Dmitriev

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

G. S. Kurskiev

Ioffe Physical-Technical Institute

Author for correspondence.
Email: gleb.kurskiev@gmail.com
Russian Federation, St. Petersburg, 194021

E. E. Mukhin

Ioffe Physical-Technical Institute

Author for correspondence.
Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

S. Yu. Tolstyakov

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

A. N. Bazhenov

Ioffe Physical-Technical Institute; Peter the Great St. Petersburg Polytechnic University

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021; St. Petersburg, 195251

Yu. V. Petrov

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

V. K. Gusev

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

N. V. Sakharov

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

N. A. Babinov

Ioffe Physical-Technical Institute; Peter the Great St. Petersburg Polytechnic University

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021; St. Petersburg, 195251

I. M. Bukreev

Ioffe Physical-Technical Institute

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194021

An. P. Chernakov

SpectralTech Ltd.

Email: E.Mukhin@mail.ioffe.ru
Russian Federation, St. Petersburg, 194223

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