scholarly journals Измерение мощности радиационных потерь и эффективного заряда плазмы на токамаке Глобус-М2

2021 ◽  
Vol 47 (2) ◽  
pp. 9
Author(s):  
Е.А. Тюхменева ◽  
Н.Н. Бахарев ◽  
В.И. Варфоломеев ◽  
В.К. Гусев ◽  
Н.С. Жильцов ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Density ◽  
Central Region ◽  
Input Power ◽  
Toroidal Magnetic Field ◽  
Plasma Current ◽  
Radiation Losses ◽  
Radiated Power ◽  
Wide Range ◽  
Measurement Results

This paper presents the measurement results of the radiated power Prad and the effective ion charge Zeff in a toroidal magnetic field of up to 0.7 T and a plasma current of up to 300 kA for a wide range of electron density, which were first obtained on the Globus-M2 tokamak. An analysis of the results demonstrated that the content of radiation losses relative to the input power decreased in the Globus-M2 tokamak compared to the Globus-M tokamak, and the measured profiles of Prad had a strong dip in the central region. In addition, a decrease of the effective ion charge Zeff with increasing electron density was observed.

THE DIFFUSION OF A HIGHLY IONIZED PLASMA ACROSS A MAGNETIC FIELD

1965 ◽  
Vol 43 (5) ◽  
pp. 855-871 ◽  
Author(s):  
O. D. Olson ◽  
H. M. Skarsgard
Keyword(s):  
Magnetic Field ◽  
Electron Density ◽  
Inhomogeneous Magnetic Field ◽  
Experimental Conditions ◽  
Degree Of Ionization ◽  
Coulomb Collisions ◽  
Wide Range ◽  
Small Collection ◽  
Toroidal Chamber ◽  
Good Agreement

The decay of electron density and temperature has been measured in a low-pressure helium afterglow by means of double floating probes of very small collection area. The plasma was contained in a glass toroidal chamber; initial gas pressures were in the vicinity of 0.030 Torr. Magnetic confining fields from 0.004 to 0.0860 Wb/m2 were used and the degree of ionization was such that coulomb collisions were dominant. Strict criteria were adopted to ensure reliable operation of the double probes. A theory of diffusion is presented which includes interactions between all species of particles. Drift effects due to the inhomogeneous magnetic field are important at the higher field strengths and are taken into account. Reasonably good agreement is found between the theoretical and observed time constants for electron-density decay over a wide range of experimental conditions.

scholarly journals Comparison of 6 Diode and 6 Transistor Mixers Based on Analysis and Measurement

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
J. Ladvánszky ◽  
K. M. Osbáth
Keyword(s):  
Field Effect Transistors ◽  
Input Power ◽  
Bipolar Transistors ◽  
Large Signal ◽  
Design Environment ◽  
Third Order ◽  
The Third ◽  
Wide Range ◽  
Measurement Results ◽  
Versus Input

Our goal is to overview semiconductor mixers designed for good large signal performance. Twelve different mixers were compared utilizing pn diodes, bipolar transistors, and/or junction field effect transistors. The main aspect of comparison is the third-order intercept point (IP3), and both circuit analysis and measurement results have been considered. IP3 has been analyzed by the program AWR (NI AWR Design Environment) and measured by two-tone test (Keysight Technologies). We provide three ways of improvement of large signal performance: application of a diplexer at the RF port, reduction of DC currents, and exploiting a region of RF input power with infinite IP3. In addition to that, our contributions are several modifications of existing mixers and a new mixer circuit (as illustrated in the figures). It is widely believed that the slope of the third-order intermodulation product versus input power is always greater than that of the first-order product. However, measurement and analysis revealed (as illustrated in the figures) that the two lines may be parallel over a broad range of input power, thus resulting in infinite IP3. Mixer knowledge may be useful for a wide range of readers because almost every radio contains at least one mixer.

Development of a novel spiral antenna system for low loop voltage current start up atSteady State Superconducting Tokamak(SST-1).

2021 ◽  
Author(s):  
Debjyoti Basu ◽  
D Raju ◽  
Raj Singh ◽  
Aparajita Mukherjee ◽  
Manoj Patel ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Antenna System ◽  
Toroidal Magnetic Field ◽  
Vacuum Vessel ◽  
Plasma Current ◽  
Test Results ◽  
Spiral Antenna ◽  
Start Up ◽  
Superconducting Tokamak

Abstract In general, superconducting tokamaks require low loop voltage current start up for the safety purpose of its poloidal field coils. The loop voltage inside the vacuum vessel of Steady-state Superconducting Tokamak (SST-1) is low in nature since its central solenoid is located outside the cryostat. The low loop voltage current start up of the SST-1 is routinely performed by Electron Cyclotron Resonance (ECR) method at the toroidal magnetic field Bt=1.5T(first harmonic) and 0.75T(second harmonic). Recently, an alternative RF based plasma current start up system had been planned for operating the machine specially for higher toroidal magnetic field regime 1.5T ≤ Bt ≤3T. The system is already developed based on an antenna system, made of series combinations of two at spiral antenna, to assist plasma current start up at lower inductive electric field. It is already tested and installed in SST-1 chamber. The system testing had been performed without background magnetic field within frequency regime 35-60MHz at present. The test results show that it can produce electron density ne ≈1016m-3 measured by the Langmuir probe in expense of 500W RF power. The spectroscopy results indicate that its capability to produce plasma density higher than 1013 m-3 and electron temperature Te = 2 -6eV. In addition, it also shows that the presence of turbulent electric field of the order of 106V/m at antenna center and finite anomalous temperature of neutral particles. Calculations show that the obtained density is enough for SST-1 low loop voltage plasma breakdown. The antenna system is also capable to produce plasma at higher frequencies. This article will discuss the development of the prototype and the installed antenna system along with their test results in detail.

Experimental observation of hot tail runaway electron generation in TEXTOR disruptions

2015 ◽  
Vol 81 (4) ◽  
Author(s):  
L. Zeng ◽  
H. R. Koslowski ◽  
Y. Liang ◽  
A. Lvovskiy ◽  
M. Lehnen ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Experimental Evidence ◽  
Electron Density ◽  
Experimental Observation ◽  
Runaway Electron ◽  
Toroidal Magnetic Field ◽  
Electron Generation ◽  
Higher Temperature ◽  
Density Threshold

Experimental evidence supporting the theory of hot tail runaway electron (RE) generation has been identified in TEXTOR disruptions. With higher temperature, more REs are generated during the thermal quench. Increasing the RE generation by increasing the temperature, an obvious RE plateau is observed even with low toroidal magnetic field (1.7 T). These results explain the previously found electron density threshold for RE generation.

scholarly journals Simultaneous feedback control of toroidal magnetic field and plasma current on MST using advanced programmable power supplies

2020 ◽  
Vol 2 (3) ◽  
pp. 035012
Author(s):  
I R Goumiri ◽  
K J McCollam ◽  
A A Squitieri ◽  
D J Holly ◽  
J S Sarff ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Feedback Control ◽  
Toroidal Magnetic Field ◽  
Power Supplies ◽  
Plasma Current

scholarly journals Runaway dynamics in the DT phase of ITER operations in the presence of massive material injection

2020 ◽  
Vol 86 (4) ◽  
Author(s):  
O. Vallhagen ◽  
O. Embreus ◽  
I. Pusztai ◽  
L. Hesslow ◽  
T. Fülöp
Keyword(s):  
Electric Fields ◽  
Ohmic Heating ◽  
Noble Gas ◽  
Temperature Evolution ◽  
Plasma Current ◽  
High Current ◽  
Radiation Losses ◽  
Initial Plasma ◽  
Wide Range ◽  
Avalanche Generation

A runaway avalanche can result in a conversion of the initial plasma current into a relativistic electron beam in high-current tokamak disruptions. We investigate the effect of massive material injection of deuterium–noble gas mixtures on the coupled dynamics of runaway generation, resistive diffusion of the electric field and temperature evolution during disruptions in the deuterium–tritium phase of ITER operations. We explore the dynamics over a wide range of injected concentrations and find substantial runaway currents, unless the current quench time is intolerably long. The reason is that the cooling associated with the injected material leads to high induced electric fields that, in combination with a significant recombination of hydrogen isotopes, leads to a large avalanche generation. Balancing Ohmic heating and radiation losses provides qualitative insights into the dynamics; however, an accurate modelling of the temperature evolution based on energy balance appears crucial for quantitative predictions.

First neutral-beam heating experiments in JET

1987 ◽  
Vol 322 (1563) ◽  
pp. 109-123 ◽  
Keyword(s):  
Power Input ◽  
Input Power ◽  
Confinement Time ◽  
Plasma Parameters ◽  
Energy Confinement ◽  
Energy Confinement Time ◽  
Radiated Power ◽  
Total Input ◽  
Wide Range ◽  
Beam Heating

Hydrogen beams at particle energies of up to 65 keV, total beam powers of up to 5.5 MW , and beam-pulse durations of up to 7 s have been injected into deuterium plasmas. Experiments were performed over a wide range of plasma parameters with limiter plasmas and inner-wall plasmas. The operational regime was extended by 70% over the current ohmic density limit. In medium density experiments, ion temperatures of ca . 6.5 keV were reached with electron temperatures of 4.8 keV. The expected degradation of energy confinement with additional heating was observed. At 4 MA plasma current and 8 MW total input power, the global energy confinement time is ca. 0.4 s. The metallic impurity concentration and Zeff drop with the rise of plasm a density during beam pulses. The rise of radiated power closely follows that of the density. In most cases, the highest value of the radiated power stays below 50 % of the power input, with very low radiation from the centre of the plasma.

scholarly journals Faraday rotation effects for diagnosing magnetism in bubble environments

2014 ◽  
Vol 1 ◽  
pp. 1-5 ◽  
Author(s):  
R. Ignace
Keyword(s):  
Magnetic Field ◽  
Electron Density ◽  
Faraday Rotation ◽  
Faraday Effect ◽  
Polarized Light ◽  
Position Angle ◽  
Toroidal Magnetic Field ◽  
Line Of Sight ◽  
Linearly Polarized ◽  
The Magnetic Field

Abstract. Faraday rotation is a process by which the position angle (PA) of background linearly polarized light is rotated when passing through an ionized and magnetized medium. The effect is sensitive to the line-of-sight magnetic field in conjunction with the electron density. This contribution highlights diagnostic possibilities of inferring the magnetic field (or absence thereof) in and around wind-blown bubbles from the Faraday effect. Three cases are described as illustrations: a stellar toroidal magnetic field, a shocked interstellar magnetic field, and an interstellar magnetic field within an ionized bubble.

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