The European Roadmap to the realisation of fusion energy presents a long-term perspective on fusion. The roadmap covers three periods: The short term which is roughly until 2030, the medium term until 2040 and the long term.
ITER is the key facility of the roadmap as it is expected to achieve most of the important milestones on the path to fusion power. Thus, the vast majority of resources...
The paper presents an overview of the design status of the ITER Radial Neutron Camera. The main role of this system is to provide, through reconstruction techniques applied to the line-integrated neutron fluxes, the time resolved measurement of the neutron and α-source profile (i.e. Neutron Emissivity, neutrons emitted per unit time and volume) in ITER. The RNC is composed of two subsystems –...
Deuterium-tritium fuel isotope composition monitoring is essential for effective plasma burning in a tokamak-reactor. This is the primary task for the Neutral Particle Diagnostic Complex, which is now being developed for the ITER tokamak. The complex comprises several diagnostics led by two Neutral Particle Analyzers (NPA) - HENPA and LENPA. The HENPA, High Energy NPA, provides registration of...
The plan for ITER is to have a comprehensive suite of diagnostics for machine protection, basic machine control, advanced plasma control, and physics studies. This includes measurements typically seen on present day fusion devices, however ITER is unlike any device presently operating. In particular the high fusion production rate and large plasma size combined with the high density and...
A short historical overview of modern systems and control theory is given. Basic systems and control concepts are introduced, with special emphasis on their relevance for Nuclear Fusion research.
Control parameters and associated processes for present-day fusion experiments are identified and classified. The state-of-the-art fusion plasma control for these categories will be presented. The...
Runaway electrons (RE) in a tokamak can deposit a significant quantity of energy onto the plasma facing components and therefore represent a threat to ITER. This paper presents the Runaway Electron Imaging Spectroscopy (REIS) diagnostic, designed to collect spectra and images produced by the RE synchrotron radiation emission. The system is composed by spectrometers covering the range from 0.4...
The spherical tokamak Globus-M was upgraded in 2018. The upgraded facility was renamed to Globus-M2 [1]. The upgrade was aimed to get the experimental conditions closer to the compact spherical tokamak-based fusion neutron source, used as a driver in a hybrid fusion-fission reactor [2]. Due to the modernization the following parameters have already been achieved: Ip = 0.4 MA, BT = 0.8 T for...
A multi-channels poloidal interferometer/polarimeter is under development for the Divertor Tokamak Test (DTT) facility, a new tokamak device whose construction is starting in Italy [1]. The aim of the diagnostics is the simultaneous measurement of the line integrated electron density, Faraday rotation and Cotton Mouton effect. The measurement of two polarimetric signals together with the...
A LIDAR Thomson scattering diagnostic is under development for the measurement of the spatial profiles of electron temperature Te and density ne of the core plasma in the DTT experiment [1]. After the first implementation in JET, a LIDAR TS diagnostic has never been replicated because its capabilities in terms of spatial resolution and repetition rate were soon surpassed by the conventional...
Bayesian inference proves to be a robust tool for the fitting of parametric models on experimental datasets. In the case of electron kinetics, it can help the identification of non-thermal components in electron population and their relation with plasma parameters and dynamics.
We present here a tool for electron distribution reconstruction based on MCMC (Monte Carlo Markov Chain) based...
The Fiber-Optic Current Sensor (FOCS) will be used in ITER to measure the total plasma current using Faraday effect. Sensing spun fibers will be placed around the Vacuum Vessel (VV) on a poloidal loop in two different VV sectors. To link the loop fibers with the reading instruments, placed several tens of meters away in electrical cabinets, a fiber bundle link is needed. This fiber bundle...
Several optical diagnostics in the ITER fusion reactor make use of big mirrors which are placed within the ITER vacuum vessel (VV), and therefore cannot have high accessibility. Deposition of dust on these mirrors may hinder the reflectivity of the mirror themselves, requiring a remote cleaning operation. The radio-frequency (RF) discharge mirror cleaning service operates a plasma discharge in...
Nuclear fusion Breeding-Blanket (BB) concepts employ attractive solid and liquid breeder materials in the form of lithium/lithium-containing compounds like Li, Pb-16Li, Li2O, LiAlO2, Li4SiO4, Li2SiO3, Li2TiO3 and Li2ZrO3. Out of these candidate materials, eutectic lead-lithium (Pb-16Li; hereafter referred to as PbLi) has gained immense focus owing to its various advantages including a high...
The future DEMO tokamak will be equipped with a multi-line of sight diagnostics which will operate as sensors to monitor and control the position and operation parameters of the DT plasma. Among the suite of sensors, an integrated neutron and gamma-ray diagnostic system is also studied to verify its capability and performance in detecting possible DEMO plasma position variations and contribute...
Fusion reactions in magnetic confinement systems generate MeV range particles, both charged and uncharged, which are key to qualify the fusion process. 14 MeV neutrons from the d+t → alpha + n fusion reaction in deuterium-tritium plasmas carry information on the fusion power and its profile, as well as on the kinematic properties of the fuel ions. 3.5 MeV alpha particles are responsible for...
Microwave diagnostics are particularly important in that they do not, in general, perturb the plasma being measured, have relatively modest access requirements, and excellent spatial and temporal resolution. Fundamental measurements include: electron temperature (ECE radiometry), electron density (interferometry, polarimetry, and reflectometry), thermal, energetic, fuel, ash, and impurity ion...
High-performance data acquisition is an essential part of plasma fusion diagnostics instruments. Typically, the measurement is conducted using a pulsed laser that generates repeated pulses that are shone into the plasma. Some of the laser light is scattered of free electrons in the plasma resulting in spectral expansion. Digitizers enable measurements of the scattered photons in a time domain...
The nuclear fusion reaction between deuterium and tritium, D(T,n)4He is the main source of energy in future thermonuclear reactors. Charged fusion products of this reaction, α-particles (4He-ions), are born with an average energy of 3.5 MeV. They transfer energy to the thermal plasma during their slowing down, providing the self-sustained deuterium-tritium plasma burn. Adequate confinement of...
JET next campaigns foresee various scans in the fuel mixture, full T operation and a 50-50 D-T campaign called DTE2 scheduled at the beginning of next decade. The main scientific objectives include the assessment of the isotopic effects on various plasma aspects: mainly on confinement, on the threshold to access the H mode and on ELM behaviour. Another very important subject of investigation...
Thomson scattering (TS) is a proven diagnostic technique that will be implemented in ITER in three independent systems. The Edge TS will measure electron temperature Te and electron density ne profiles at high resolution in the region with r/a>0.8 (with “a” the minor radius). The Core TS will cover the region r/a<0.85 and shall be able to measure electron temperatures up to 40 keV. The...
In magnetically confined fusion reactors, energetic ions must be kept well confined until they slow down to the plasma bulk through Coulomb collisions. Energetic ions are, however, subject to a wide variety of cross-field transport due to their large velocities, long mean free path and slowing down times. Indeed, a broad spectrum of magnetohydrodynamic (MHD) fluctuations have been observed to...
ITER will be equipped with a five channel combined toroidal interferometer and polarimeter (TIP) system to provide line-integrated density for feedback control and density profile reconstruction as well measurements of instability-induced core density fluctuations. In the current design, two-color vibration compensated interferometry is carried out at 10.59 μm and 4.6 μm using a CO2 and...
The Divertor Tokamak Test (DTT) facility [1], whose construction is starting in Frascati, will require robust and reliable diagnostics for the correct operation of the machine and the characterization of the plasma discharge.
For this purpose, we are studying a common-path dispersion interferometer/polarimeter for the detection of plasma electron density and magnetic field in 2 different...
The development of MITICA, the prototype for a neutral beam injector for ITER, drives the interest in investigating HV insulation in vacuum. The High Voltage Padova Test Facility (HVPTF) is an experimental device which has the double aim of studying the physical phenomena underlying the voltage holding in vacuum and testing technical solutions to increase the breakdown threshold. HVPTF...
The inaugural Deuterium acceleration campaign in the SPIDER negative ion source facility in Padua has recently taken place. The first neutrons generated by Deuterium-Deuterium fusion reactions (2.5 MeV) have been recorded, occurring from the collision of accelerated Deuterium with Deuterium absorbed by the beam dump of SPIDER. A neutron detector based on a novel EJ276 plastic scintillator has...
On preliminary considerations towards development of radiated power and SXR diagnostics for DEMO
M. Chernyshova, K. Malinowski, S. Jabłoński, T. Fornal, K. Mikszuta-Michalik, T. Czarski, K. Tomaszewski
Institute of Plasma Physics and Laser Microfusion, Hery 23, 01-497 Warsaw, Poland
maryna.chernyshova@ipplm.pl
Currently, a new X-ray detection technology is required for...
A new neutron time-of-flight spectrometer (TOF-X) is proposed for simultaneous measurement of the 2.5 and 14-MeV neutron emission groups such as due to the d+d->τ+n reaction and triton burn-up reaction tdd+d->α+n. The aim of the instrument is to provide data for the study of the slowing-down and confinement of 1-MeV tritons in D plasmas that can serve as proxy for the same information on...
Interferometry has to this day been an essential diagnostic on any medium to large scale fusion experiment, primarily due to its resilience and “simplicity”. These properties are quintessential for the diagnostic principle’s success and establish it as the primary density control diagnostic on most fusion machines so far. Polarimetry is a natural extension to the interferometer concept, which...
Among other effects of interest for the optimisation of fusion plasma machines, plasma-wall interaction is one of the most investigated. Through plasma-wall interaction, the first wall material may be eroded and impurities enter into the plasma, where they can produce soft X-rays (SXR) from 5 to 20 keV. To study the rate and energy of such SXR emission it is necessary to develop adequate SRX...
Four ITER diagnostics are being developed in China, namely Neutron Flux Monitors (NFM), Radial X-Ray Camera (RXC), Equatorial Port 12 (EP#12) Integration, and Divertor Langmuir Probes (DLP). Based on functional specifications, China Domestic Agency (CNDA) performs the design of the diagnostic system besides delivering the diagnostic components. NFMs, located in equatorial port 1, 7, 8, 17,...
ITER Japan domestic agency (JADA) procures five diagnostics for the ITER project; micro fission chamber (MFC), edge Thomson scattering diagnostics (ETS), poloidal polarimeter (PoPola), divertor impurity monitor (DIM) and divertor infrared thermography (IRTh). JADA has designed each individual diagnostic system taking into account the following: (1) high radiation heat (<1 MW/m2) and high...
Specifically designed to test power exhaust solutions, DTT will represent in the near future the closest approximation to ITER and DEMO, with its magnetic field (6T ), plasma current ( 5.5 MA), high power density (45 MW, R= 2.19, m a= 0.7 m, k=1.7), actively cooled first wall components and superconducting coils. A series of diagnostics, system is being designed to cover all the important...
Diagnostic systems are essential to perform machine operation and physics understanding for magnetic fusion experiments. The 14th experimental campaign from Korea Superconducting Tokamak Advanced Research (KSTAR) device has passed since the first experimental campaign was carried out successfully in 2008. The basic diagnostic systems such as magnetic diagnostics, interferometer, inspection...
Between the various compact diagnostics systems, the hybrid CMOS-based and gas electron multiplier (GEM) detectors of multiple sizes, types, and combinations can offer a real “swiss-knife” solution for the experimental investigation of ionizing radiation. They were used, for many years, by the LabNIXT group of ENEA Frascati on many experimental setups (FTU, KSTAR, EAST, VEGA, GEKKO, etc.). In...
The heat and particle exhaust in tokamaks is guided to a dedicated region called the divertor. Unmitigated, the expected power fluxes impacting the divertor targets during reactor relevant operation exceed present-day engineering limits [1]. Real-time feedback control of plasma detachment, a regime characterized by a large reduction in plasma temperature and pressure at the divertor target, is...
Integration studies of diagnostics in fusion grade devices (e.g. ITER, DEMO) aim to provide concepts and technical solutions for installation of diagnostic components that can perform the required measurements in a nuclear harsh environment while providing an optimized interface with the baseline tokamak systems and services and offering high levels of reliability and lifetime.
The challenges...
Within the European development of the concept for a future tokamak demonstration fusion power plant (DEMO) [1] the studies on the plasma diagnostic and control (D&C) system are progressing to prepare the basis for reliable plasma operation at high overall performance [2]. A variety of plasma diagnostics will be employed on DEMO in order to provide an accurate knowledge of the actual plasma...
Diagnostics have been a key element in fusion research development, and often served as an essential component in understanding the underlying science of fusion-grade plasmas. However, as the performance of fusion devices approaches and reaches ignition, new challenges arise from environmental conditions such as radiation (e.g. neutrons, gammas), long term exposures to front-end components...
Runaway electron generation remains one of the major challenges to the success of high-current tokamaks. Investigation of runaway electron physics is a crucial step towards developing effective prediction, avoidance, and mitigation strategies to reduce the impact of these dangerous events. Valuable information on the runaway electron distribution function can be obtained performing spectral...
Measurement of the x-ray spectra of the He-like Ni ions (Ni$^{26+}$) and their dielectronic satellites (Ni$^{25+}$, Ni$^{24+}$, and Ni$^{23+}$) plays a crucial role in determination of electronic and ionic temperature of plasma in the JET device. Because $n\ge3$ satellites of Ni$^{25+}$ overlap with resonance 'w' line of Ni$^{26+}$, it is important to reconstruct the structure of these...
The reconstruction of the distribution function of runaway electrons (RE) in magnetically confined fusion plasmas can give insights on the runaway electron beam dynamics during plasma disruptions and it may help at understanding the effect of disruption mitigation techniques on the RE velocity space. When RE are assumed to be purely co-passing, i.e. to have a pitch=1, a one dimensional...
A new profilometry diagnostic method is investigated in this work to measure the plasma electron density profile in front of the Ion Cyclotron Range of Frequencies (ICRF) antennas. As a reference scenario for our numerical study, the Divertor Tokamak Test (DTT [1]) ICRF antennas and plasma will be considered. Specifically, the profilometry needs to solve an inverse scattering problem, which is...
Diamond is a semiconducting material widely used in technological applications where extreme operating conditions are required: its outstanding physical and electrical properties (high band-gap, high thermal conductivity, high radiation hardness, high charge carrier mobility, visible-band radiation blindness) make feasible the realization of fast, low noise and well performing radiation...
Stellarators have fundamental advantages, providing steady-state magnetic confinement of fusion plasmas without large toroidal currents and without the associated instabilities and operational limits. In order to fully exploit these advantages, the design of stellarators has to undergo elaborate optimization procedures. Optimization criteria range from reduced neoclassical transport and...
The LHD is the world's largest (30 m -3) helical plasma confinement device, with a major radius of 3.9m and an average small radius of 0.65m. In order to make the best use of the characteristics of the three-dimensional magnetic coordination, a number of diagnostics have been developed and applied. For profile measurements, electron temperature and density by Thomson scattering,...
A fusion-fission hybrid (FFH) reactor is a complex machine, which includes a tokamak fusion neutron source and two blankets: the tritium regeneration and the actinide burner zones. These three systems need their own diagnostics and controls. Problems associated with the implementation and integration of control systems call for a simplified technology. In this paper, a short overview of the...
The TJ-II is a heliac-type stellarator device with major radius of 1.5 m and averaged minor radius ≤0.22 m that has been operated at Ciemat, Madrid since 1998.1 Its magnetic field (B ≤1 T at plasma axis) is generated by a system of poloidal, toroidal and vertical field coils. Plasmas created with hydrogen, deuterium or helium, tpulse ≤300 ms, are heated using two gyrotrons operated at 53.2...
The Large Helical Device (LHD) has been operated with deuterium gas since March 2017 [1]. One of primary objectives of the LHD deuterium operation is to demonstrate energetic-particle (EP) confinement in a toroidal magnetic field with three dimensionality, and to contribute to comprehensive understanding of EPs in toroidal magnetic confinement system. Because beam-driven DD neutron and...
Fusion and hybrid fusion-fission reactors (HFFR) are characterized by having intense neutron and gamma fluxes and high working temperature. This is particularly relevant for the breeding blanket region (BB) whose environment results very hostile to nuclear detectors to be used to monitor/measure fundamental nuclear parameters like e.g. neutron/gamma fluxes and spectra, tritium production, etc....
Divertor Langmuir probe (DLP) system is one of ITER diagnosis used to measure the divertor parameter profiles such as ion saturation current, electron temperature, density, for ITER advanced control and physics research. The system consists of three components: 1) 400 Langmuir probes installed on the side of monoblock in 5 cassettes. DLPs should sustain 10MW/m2 Steady-state heat load and...
Abstract. The ITER Electron Cyclotron Emission (ECE) diagnostic has primary roles in providing measurements of the core electron temperature profile and the electron temperature fluctuation associated with the Neoclassical Tearing Modes (NTM). Indian domestic agency (IN-DA) and US-DA share the responsibility to supply this diagnostic. The IN-DA scope has passed its Preliminary Design Review...
Neutral pressure gauges of the ASDEX type [1] have been adapted for stable and reliable operation in magnetic fusion experiments. Neutral pressure gauges using an electron emitting LaB6-crystal aligned with the magnetic field do not experience damage due to the j × B force as observed in neutral pressure gauges with filaments of thoriated tungsten. They were successfully operated in hydrogen...
The Fibre Optic Current Sensor (FOCS) is a system that will perform plasma current measurements at ITER during long plasma discharges under intense nuclear radiation. Plasma current measurements are important for safe machine operation. The FOCS must perform measurements is harsh tokamak environment, which include strong magnetic fields, high temperatures, and also significant levels of...
At present, the only method for assessing the fusion power throughput of a reactor relies on the absolute measurement of 14 MeV neutrons produced in the D-T nuclear reaction. [1]
For ITER and DEMO, however, at least another independent measurement of the fusion power is required.
The 5He* nucleus produced in the D-T fusion reaction has two de-excitation channels. The most likely is its...
The Neutral beam Injectors of the ITER experiment will be based on negative ion sources for the generation of beams composed by 1 MeV H/D particles. The prototype of these sources is currently under testing in the SPIDER experiment, part of the Neutral Beam Test Facility of Consorzio RFX, Padua. In SPIDER, the negative ions are extracted and accelerated from the source by means of a three...
SPIDER, the full size ITER NBI ion source, aims to prove the ITER requirements in terms of the ion source performance, a beam uniformity better than 90% and a low beam divergence. The SPIDER experiment can operate in deuterium, thus producing beam-target D-D fusion neutron emissions. These emissions can be used to evaluate the beam uniformity as well as machine parameter dependence, since the...
The Phase Contrast Imaging (PCI) diagnostic is an absolutely calibrated internal reference interferometer that creates an image of line-integrated electron density fluctuations [H.Weisen, Rev. Sci. Instrum. 59 1544 (1988)]. Detector arrays with appropriate frequency bandwidth are used to extract the spatial structure of the plasma imaged by the diagnostic.
A novel PCI system has been...
The power exhaust problem is one of the most critical challenges for realizing a commercial fusion power plant. High dissipative divertor and SOL condition, up to 90% of radiation, are now routinely obtained in several tokamaks providing a possible solution to protect the plasma facing components. However, a complete understanding of tokamak SOL and divertor physics is key to extrapolate with...
Charge Exchange Recombination Spectroscopy (CXRS) is a powerful diagnostic tool for fusion plasma in tokamaks [1, 2]. The ITER CXRS system will provide spatially resolved measurements of the ion temperature, low-Z impurity density and rotation velocity. These plasma parameters are extracted from the active charge-exchange (CX) spectral line, emitted during high-energy neutral beam injection...
A major challenge in nuclear fusion research is the coherent combination of data from heterogeneous diagnostics and modelling codes. Measured data from different diagnostics often provide information about the same subset of physical parameters. Additionally, information provided by some diagnostics might be needed for the analysis of other diagnostics. A joint analysis of complementary and...
Abstract: Quantitative modeling of the fast electron physics from first principles has always been a challenging but crucial task in order to understand observations from microscopic processes in the plasma. Synthetic diagnostics play a central role in the data analysis, allowing to make direct comparisons between modeling and measurements, thus reducing the uncertainties on the physical...
\begin{document}
\title{
Plasma equilibrium reconstruction in a Tokamak
}
\author{J. Blum, C. Boulbe, B. Faugeras\
{ \small Laboratoire J.-A. Dieudonn\'e (UMR 7351),} \
{\small Universit\'e C\^ote d'Azur, Parc Valrose, 06108 Nice Cedex 02, France} \
{\small email: jblum@unice.fr}
}
\date{}
\maketitle
%\tableofcontents
%\clearpage
The problem of the...
Various private investors have recently shown their interest into nuclear fusion as a source of clean energy. One of the most challenging project is SPARC, a DT tokamak under development by Commonwealth Fusion Systems in collaboration with the Massachusetts Institute of Technology and contribution from investors among which the Italian ENI. The SPARC [1] tokamak is at present under design and...
The preparation of the T-15MD tokamak for the first experiments has been almost completed now. The main parameters of T-15MD are: R = 1.48 m, a = 0.67 m, B = 2.0 T, Ipl = 2.0 MA. Scientific objectives of the T-15MD are: investigation of the particle and energy transport in the ITER-like plasma configuration; disruption mitigation system development; plasma turbulence investigations; plasma...
Equations of Stokes vector formalism or the technique of angular variables are usually used to analyze the evolution of the electromagnetic wave polarization state in a tokamak plasma. Both approaches assume that plasma is a weakly anisotropic and smoothly inhomogeneous media. The description of polarization changes for the plasma that does not meet these assumptions (e.g. in the region of...
