Thomson scattering of the core edge and divertor plasma regions of a tokamak with reactor technologies is discussed. The rationale and choice of technical solutions are given, the composition of the ...Thomson scattering diagnostic complex is discussed, as well as an estimate of the accuracy of measuring both electron temperature and density. Particular attention is paid to ensuring the functionality of the proposed diagnostics in the reactor mode of the tokamak operation and the results of testing diagnostic equipment in the experiments on Globus-M2 tokamak.
The results of measuring the electron temperature and density spatial distributions in plasma of the Globus-M2 tokamak using the Thomson scattering diagnostics are presented. The diagnostics provides ...measurements throughout the entire tokamak discharge, starting from time of gas breakdown. The Thomson scattering data were analyzed in order to determine the positions of the last closed flux surface, the plasma magnetic axis, and the radius of inversion during the saw-tooth oscillations. The results of measurements performed during the internal reconnection of magnetic field lines are presents, as well as the dynamics of spatial distributions of electron temperature, density and pressure during the plasma transition to the H-mode. The results of measuring the electron temperature distribution in the scrape-off layer using the Thomson scattering diagnostics are also presented for distances up to 4 cm outside the last closed flux surface.
Divertor Thomson Scattering on Globus-M2 Ermakov, N. V.; Zhiltsov, N. S.; Kurskiev, G. S. ...
Plasma physics reports,
12/2023, Letnik:
49, Številka:
12
Journal Article
Recenzirano
We present the first Thomson scattering (TS) measurements of electron temperature in the lower divertor of the Globus-M2 tokamak. The divertor TS diagnostics is designed for local measurements of the
...T
e
(
z
,
t
) in the range of 1–100 eV and
n
e
(
z
,
t
) in the range of
m
–3
. Parameters of the probing Nd:YAG laser are as follows 1064 nm/2 J/100 Hz/3 ns. The probing chord is launched vertically at
R
= 24 cm and covers areas of the inner leg, vicinity of separatrix and private flux region. Along probing chord of 110 mm, 9 spatial points were realized. Advanced filter polychromators were used to analyze Thomson scattering spectra.
Digital filter polychromator for Thomson scattering applications Kurskiev, G.S.; Chernakov, Al.P.; Solovey, V.A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2020, Letnik:
963
Journal Article
Recenzirano
The paper describes the digital filter polychromator developed for Thomson scattering (TS) diagnostics. The device having ultra-low noise, high-speed detection system and up to 7 spectral channels is ...equipped with digitizer and single board computer for system control and data processing. The data acquisition system is capable to detect very short laser pulses of few ns width with low magnitude. This feature opens up new possibilities for the TS diagnostics design in modern fusion devices, which includes: operation with high background illumination, measurement of very low electron temperature and density at the plasma edge and scrape-off layer (SOL), separation of the TS signal and the stray light coming with a delay of several ns. The analysis of the TS signal waveform also gives a possibility to distinguish the TS and Mie scattering from the dust particles that is important for measurements in SOL. Owing to compactness and ultra-low energy consumption both optical and data processing units interfaced with optical Gigabit Ethernet were combined in a stand-alone device. Such all-in-one design with optical fiber input and optical digital output provides enhanced resistance to electromagnetic disturbances and simplify operation. A set of such polychromators can be mounted in a standard 19” rack and can be integrated with outer CODAC (Control, Data Access and Communication) system. Testing of the polychromators at the Globus-M2 tokamak has shown excellent performance of the developed serial devices.
This work describes the real-time application of the Thomson scattering diagnostics. The upgraded data acquisition system of the Globus-M2 spherical tokamak provides real-time data processing with ...the delay
<
2
.
4 ms for 128 scattering signals from 11 spatial points. The achieved processing performance meets the requirements for Thomson scattering diagnostics of modern thermonuclear facilities and ITER in particular. The paper demonstrates the possibility of plasma electron density control, using Thomson scattering data in the feedback loop.
diagnostics of the plasma electron component by the metho d of Thomson scattering
T
e
(
R
,
t
) of laser radiation makes it possible to reliably measure the spatial distributions of the electron ...temperature and density. One of the obstacles to the implementation of TS diagnostics in thermonuclear reactors is the distortion of the spectral characteristics of the optical system due to radiation-induced absorption and contamination of optical elements with erosion products of the first wall. As a consequence, the reliability of measurements by the TS method will decrease over time. The paper describes the method of multi-laser Thomson scattering, which will solve this problem. The results of the first experiments on the Globus-M2 tokamak are also presented.
This note is devoted to a filter polychromator combining built-in optical, data acquisition and processing subsystems designed for electron temperature and density measurements in fusion plasma by ...Thomson scattering (TS). Special attention is paid to assessing the accuracy of TS signals measured in the polychromator spectral channels. The potential for estimating TS error caused by background emission is demonstrated using high-pass signal. The recent polychromator tests have shown APD gain stabilization better than ±0.5% over the ambient temperature range from 17.5 °C to 35 °C
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.
Renewable energy sources provide an unstable energy flow to the units of an autonomous energy complex. Therefore, in order to use the electrolyzer as an element of the considered complex, it is ...necessary to determine the optimal range of changes in the current density and evaluate the effect of operating characteristics of the electrolysis process on the evolution of H2 (O2) when the electrolyzer power supply is disconnected for 13 seconds against the background of a continuous base current level. Purpose. The main purpose of the research is to determine the rational range of changes in the current density supplied to a monopolar membrane-free high-pressure electrolyzer, as well as to determine the effect of a discrete current supply on electrochemical reactions during electrolysis. Methodology. Comprehensive studies on the electrochemical processes of water decomposition in alkaline electrolyte with the formation of hydrogen and oxygen in an experimental construction make it possible to cyclically supply power to the electrolyzer with visual control of the considered processes. Findings. The technology of cyclic generation of hydrogen and oxygen, which eliminates the need to use separating ion-exchange membranes, is considered. A rational range of changes in the current density on a membrane-free monopolar high-pressure electrolyzer with the usage of electrodes made of metals with variable valence is established. The influence of the discrete supply of electrical energy to the electrolysis cell is determined depending on the electrochemical reactions occurring on the active iron electrode. Theoretical values of the voltage of the oxidation and reduction of the iron electrode active mass, as well as the voltage on the half-cycle of hydrogen evolution during the electrolysis of water, are calculated. Originality. An increase in the blackout time from 1 to 3 s leads to a corresponding increase in time of the oxidation process on the hydrogen half-cycle by a factor of 2.4. In addition, the total amount of hydrogen (oxygen) released during the corresponding half-cycles remains unchanged and amounts to Practical value. The optimal range of current density for the operation of a membrane-free high-pressure electrolyzer is in the range of 200400 A/m2. Under such conditions, an intense redox process of the iron electrode active mass occurs. Electrical energy consumption in this case is in the range of 3.94.1 kW h/m3. An experimental study on the electrolyzer discrete power supply effect on its ability to generate gas is carried out. This makes it possible to supply electrical energy to the electrolysis cell directly from the primary energy source (sun, wind) as part of the energy technology complex.
Вщновлюваш джерела енергп забезпечують нестабшьний полк енергп до установок автономного енергетичного комплексу. Тому, щоб використовувати електролшер в якосл елемента комплексу, що розглядаеться, ...необидно визначити оптимальний дшпазон змши густини струму та оцшити вплив робочих характеристик процесу електролшу на видшення газу Н2 (О2), коли електроживлення електролНера вимкнено на 1-3 секунди на mí безперервного базового риня струму. Мета. Основною метою дослщжень е визначення рацiонального дiапазону змши густини струму, що подаеться на монополярний безмембранний електролiзер високого тиску, а також визначення впливу дискретно!' подачi струму при електролш на електрохiмiчнi реакцп. Методика. Комплекснi дослщження електрохшшних процешв розкладання води в лужному електролiтi з утворенням водню та кисню в експериментальнш установщ, що дозволяе циклiчно подавати електричне живлення на електролiзер з вшуальним контролем зазначених процешв. Результати. Розглянута технологи циклiчного генерування водню й кисню, що виключае необхiднiсть використання роздшових iонообмiнних мембран. Встановлено рацюнальний дiапазон змiни щiльностi струму на безмембранному монополярному електролiзерi високого тиску з використанням електродш, виготовлених О метали зi змiнною валентшстю. Визначено вплив дискретно! подачi електрично! енергп' на електролiзну комiрку в залежностi вщ електрохiмiчних реакцш, що протiкають на активному залшному електродi. Розрахованi теоретичнi значения напруги пролкання реакцiй окислювання й врдновлення активно! маси залiзного електрода, а також напруга на нашвци^ видшення водню у процеш електролНу води. Наукова новизна. Збiльшения перюду вщключення живлення з 1 до 3 с призводить до вщповщного збшьшення часу процесу окислення на напiвциклi видшення водню у 2,4 рази. Але загальна кшьюсть водню (кисню), що видшяеться на в!дпов!дних напiвциклах, залишаеться незмшною i становить VH = 15 мл(^ = 7.5 мл). Практична значимтсть. Оптимальний дiапазон щшьносл струму для роботи безмембранного електролНера високого тиску знаходиться в межах 200-400 А/м2. За таких умов вщбуваеться найактившший окислювальновщновлювальний процес активно! маси залiзного електрода. Споживання електроенергй' в цьому випадку знаходиться в межах 3,9-4,1 кВт * год/м3. За цих умов споживання енергп стандартними мембранними електроль зерами (у залежносл в(д температури та тиску процесу, якостi електродш i ряду iнших факторiв) варшеться вщ 4,3 до 5,2 кВт * год/м3 водню. Проведено експериментальне вивчення впливу дискретного живлення електролНера на його здатшсть до газоутворення. Це дае можливiсть поставляти електричну енергiю на електролшну комiрку безпосередньо вщ первинного джерела енергп (сонце, вгтер) у складi енерготехиологiчного комплексу.
PDF
