Conveners
Talks: Reflectometry
- Roland Sabot (CEA, IRFM, CEA Cadarache, F-13108 Saint Paul Lez Durance, France)
- Filipe da Silva (Instituto Superior Tรฉcnico-Instituto de Plasmas e Fusรฃo Nuclear)
Talks: Real time systems and profile inversion
- Jia Huang
- Dirk Stieglitz (IPP Garching)
- Maylis Carrard (CEA)
Talks: Profile systems
- Frederic Clairet (CEA)
- Janmejay Buch (Institute for Plasma Research)
- Umesh Kumar (EPFL)
Talks: Reflectometry development on HSX
- Henrique Oliveira Miller (University of Wisconsin Madison)
- Xiang Han (University of Wisconsin-Madison)
- Michael Richardson (University of Wisconsin-Madison)
Talks: Theory and synthetic diagnostic development
- Kaixuan Ye (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, Peopleสผs Republic of China)
- Antoine Jamann (CEA, IRFM, F-13108 Saint Paul-lez-Durance, France)
- Garrard Conway (IPP Garching)
Talks: Multi-channel microwave system development on EAST
- Liutian Gao (USTC)
- Wenxiang Shi (University of Science and Technology of China)
- Gongshun Li (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, Peopleโs Republic of China)
Talks: Microwave system development on HL2A/3
- Ruihai Tong (SWIP)
- Weichu Deng (Southwestern Institute of Physics, China)
- Yu Zhou (Southwestern Institute of Physics (SWIP), China)
Talks: Technology development
- Valentina Nikolaeva (Commonwealth Fusion Systems)
- Yilun Zhu (UC-Davis mmWave Research Center)
- Antoine Sirinelli (ITER Organization)
Talks: Intensity refractometry, Plasma density fluctuations and Turbulence
- Oleg Krutkin (EPFL)
- Jason Smoniewski (IPP Bereich Garching)
- Maria Usoltseva (Max Planck Institute for Plasma Physics)
Talks: nT-crossphase estimation: Reflectometry and CECE
- Gavin Weir (Max Planck Institute for Plasma Physics)
- Branka Vanovac
- Carsten Lechte (Institute of Interfacial Process Engineering and Plasma Technology IGVP, Stuttgart, Germany)
Talks: Reflectometry on W7-X
- Thomas Windisch (IPP)
- Andreas Krรคmer-Flecken (Forschungszentrum Jรผlich)
- Emmanouil Maragkoudakis (CIEMAT)
Talks: Wendelstein 7-X: ECRH and radiometry
- Neha Chaudhary (IPP Bereich Greifswald)
- Torsten Stange (Max Planck Institute for Plasma Physics)
Talks: Phased array antennas and wavenumber measurements
- Seong-Heon Seo (Korea Institute of Fusion Energy)
- Laure Vermare (LPP)
- Tokihiko Tokuzawa (National Institute for Fusion Science)
Talks: Edge flows and L-H Transitions
- Ondrej Grover (Max Planck Institute of Plasma Physics)
- Josรฉ Vicente (Instituto de Plasmas e Fusรฃo Nuclear, Instituto Superior Tรฉcnico, Universidade de Lisboa)
- Sascha Rienรคcker (Laboratoire de Physique des Plasmas (LPP), CNRS, Sorbonne Universitรฉ, รcole polytechnique, Institut Polytechnique de Paris, Palaiseau, France)
Talks: Plasma position reflectometry (PPR)
- Filipe da Silva (Instituto Superior Tรฉcnico-Instituto de Plasmas e Fusรฃo Nuclear)
- Stรฉphane Heuraux (University of Lorraine, Institut Jean Lamour)
- Jorge Santos (Instituto de Plasmas e Fusรฃo Nuclear - Instituto Superior Tรฉcnico)
Talks: Closing session, Coffee and Cakes
- There are no conveners in this block
A tutorial introducing the place of microwave diagnostics, and reflecometry especially, in plasma physics and controlled magnetic confinement fusion research.
Profile reflectometers are ubiquitous on magnetic fusion devices. For X-mode reflectometry, the standard method for density reconstruction has been the Bottollier-Curtet method [1] or its derivatives [2]. All these methods reconstruct recursively the density profile from the phase. However, the phase is an ill-defined parameter: the phase extraction is highly non-linear becoming very noisy at...
Reflectometry is anticipated to play a significant role in plasma positioning, shaping, and tracking for DEMO, potentially replacing magnetic diagnostics. Initial progress has been made through experiments, theory, and simulations, but there is still much work to be done. Our EUROfusion Enabling Research (EnR) Project, involving experts and developers of reflectometry systems in Europe, aims...
The electronic density ne is a major parameter, both for real-time tokamak control and plasma physics. On the WEST tokamak, X-mode reflectometry provides post-treatment radial density profiles ne(r) with a centimeter precision[1]. The current reconstruction method initializes the profile using the signal amplitude jump at the edge plasma position and reconstructs the profile using a...
The real-time distribution of density profiles serves as valuable data for monitoring plasma density and position. Presently, devices rely on magnetic measurement diagnostics to obtain reference data for these purposes. The microwave reflectometer serves as a widely employed density profile diagnostic system on magnetic confinement fusion devices across various nations. It is also planned to...
The ASDEX Upgrade tokamak has a swept O-mode reflectometer for measuring density profiles, which is used as a stand-alone diagnostic and as part of the Integrated Data Analysis framework. This contribution presents developments for the stand-alone analysis using Bayesian methods for initialisation and inversion, with uncertainty quantification for both.
Stand-alone analyses using techniques...
Results from FMCW reflectometry measuring density profiles for the first time on Aditya-U tokamak are reported. Two channels in 18-28 GHz and 26-40 GHz range are established at IPR. The reflectometer was operated in O-Mode with its horn antennae placed outside the vacuum vessel. The diagnostic was calibrated in laboratory and also verified in-situ. Characterisation of the instrument for system...
The performances of the WEST tokamak plasmas relies on additional heating system such as ICRH (Ion Cyclotron Resonance Heating) and LHCD (Lower Hybrid Current Drive). However, the coupling efficiency of these additional power systems strongly depends on the electron density in front of their launchers. Thus, in addition to the reflectometer with waveguide routes already installed in a LH...
The accurate and precise measurement of the density profile and characterization of turbulence in a fusion plasma is of paramount importance and achieving this through non-invasive diagnostics is a key area of interest. The microwave reflectometer stands out as a potential candidate for such measurements, with short-pulse reflectometry presenting a uniquely appealing approach.
In this method,...
A dual band frequency-modulated continuous wave (FMCW) reflectometry is developed to measure the density profile and its associated fluctuation on Helically Symmetric eXperiment (HSX). This reflectometry equips a switch to select the frequency source between two voltage controlled oscillators (VCOs) to the transmitter, realizing an extended operational frequency range from Ku to K bands (14.5...
Reflectometry is one of the workhorse diagnostics at the Helically Symmetric Experiment (HSX) to study turbulence-induced density fluctuations in the frequency range from 10 โ 100 kHz. To further optimize the system for turbulence and flow studies, it is planned to upgrade the HSX reflectometer system into a Doppler Reflectometer. With the new setup, the diagnostic will be capable of providing...
A density fluctuation and profile reflectometer diagnostic is in place on the Helically Symmetric Experiment (HSX). It is currently installed as a perpendicular incidence reflectometer with a shared launching and receiving antenna. Probing microwaves range from 14.5-25 GHz, and either O or X-mode propagation can be selected. Preliminary modelling of this reflectometer with the ray-tracing code...
This contribution reports the conclusions of a lengthy modelling study (cf. previous reports [1]) using 2D full-wave (IPF-FD3D) and 3D beam-tracing (Torbeam) codes, on the behaviour, and in particular the physical and spectral resolutions, of microwave Doppler reflectometry / backscatter diagnosis of fusion plasmas. Using a large database (including simulation spatial weighting-functions &...
Microwave reflectometry is a powerful diagnostic that can measure the density profile and will be used in the future fusion devices such as ITER, so understanding of how the reflected signals are affected by plasma perturbations is of prime importance. In EAST, profile reflectometry has been developed as routine diagnostic since 2013, [1]โ[3]. In this work, a set of full-wave simulation codes...
In magnetized plasmas, turbulent mechanisms play a crucial role in governing the anomalous transport of energy and particles. These mechanisms are challenging to measure and require high-resolution diagnostics. Microwave reflectometry emerges as a versatile and cost-effective tool capable of measuring electron density fluctuation resulting from MHD or micro-turbulence. On the other hand,...
The W-band doppler backscattering system on EAST, which was installed in 2018 [1], has been upgraded. The new design uses a beam splitter and two antennas to separate signal launching and receiving, thus avoiding signal noise caused by the reflection of the W-band filter. The frequency intervals between adjacent channels have been increased from 400 MHz to 1 GHz to broaden the diagnostic area....
A muilti-channel E-band (60โ90 GHz) Doppler backscattering (DBS) system with X-mode polarization has been installed on the Experimental Advanced Super-conducting Tokamak (EAST)1. In September 2023, this system was upgraded to the ten-channel E-band DBS in order to cover a larger radial range in one shot. The upgraded system can launch 16 fixed microwave frequencies in the range of 60โ90 GHz...
As a conventional reflectometry, W-band Poloidal Correlation Reflectometry (PCR) has been operated successfully on EAST tokamak since 2018 and has become a key diagnostic tool for measuring electron density fluctuation in plasma core. In this report, a new experimental observation that the turbulence spectrum detected by this PCR system exhibits an asymmetry and induced Doppler shift f_D...
Recently, a flexible Doppler backscattering system (DBS) has been developed for the HL-3 tokamak to obtain radial profiles of the perpendicular propagation velocity during L-mode and H-mode. [1โ4] It operates within the frequency range of 24.4-50.4 GHz, encompassing both the Ka-band and Q-band. In frequency hopping mode, its minimum step frequency is 0.2 GHz. For heterodyne detection, the...
A 105 GHz collective Thomson scattering (CTS) diagnostic for measurement of velocity distribution of fast ions has been developed on HL-2A tokamak. A high gain Cassegrain antenna installed below the gyrotron launcher is used to receive the scattering beam from the central chord inside the vacuum vessel. The transmission system and notch filters provide a suppression level >60 dB at 105 GHz, to...
A novel multichannel Doppler backscattering (DBS) system based on a comb generator has been designed and tested for application on the HL-3 tokamak. DBS diagnostic is widely used to measure the localized density fluctuations and the propagation velocity of turbulent structures[1-4]. Microwave is launched at a frequency that approaches a cutoff layer in the plasma and at an angle that is...
Calibration is a key step in the development and operation of any measurement instrument. It allows to quantify the accuracy and precision of the measurement. A careful calibration enables the user to understand the performance of the different parts of the instrument and therefore permits the compensation of systematic errors. Regular calibrations also give some insights on the long-term...
SPARC is a compact, high-field, D-T tokamak that is presently under construction and will be used to de-risk the high-field path to commercial fusion energy. Diagnostic systems are entering the final design stage and will be used for real-time control and to close science gaps needed to design ARC. An Edge Scanning Reflectometry (ESRL) system for SPARC is included in the Campaign #1...
The microwave reflectometer serves as a crucial diagnostic tool for plasma density measurements. In modern large-scale, high power fusion plasma facilities, reflectometers require lengthy millimeter-wave transmission lines to shield the microwave transmitting/receiving systems from harsh radiation environments, thereby ensuring the diagnostic system's integrity. Enhancing the output power...
Intensity refractometry is a recently developed technique for plasma density measurements in laboratory plasmas with large density gradient, such as in tokamaks or stellarators. It relies on measuring the change of both phase and amplitude of a microwave beam with the O-mode polarization passing through the plasma. The direction of the microwave beam propagation is perpendicular to the density...
A Short Pulse Reflectometer (SPR) diagnostic has been developed for the TCV tokamak [1]. It utilizes short (~1 ns) microwave pulses to probe plasma in the presence of a cut-off. Pulse delays corresponding to different probing frequencies are then used to reconstruct the electron density profile, similar to conventional fast-sweeping reflectometry.
Within this work, the capabilities of SPR to...
The Helically Symmetric eXperiment (HSX) has previously demonstrated reduced neoclassical transport and reduced flow damping with quasisymmetry (QHS) as compared to a degraded-symmetry (Mirror) configuration, but the effect of quasisymmetry on the anomalous transport is less clear. Here, experimental heat flux and density fluctuation measurements are compared to gyrokinetic simulations of...
Connecting experimental results with turbulence simulations can require fullwave simulations of regular and Doppler reflectometry when high fluctuation levels are probed with high frequencies (X mode). For this, the experimental kinetic profiles and power fluxes are matched in the gyrokinetic turbulence code GENE, whose output density fluctuations are used in the fullwave simulations with...
Turbulent heat and particle transport are related to the amplitude of density, temperature,
potential fluctuations, and the cross-phase angles between these fluctuating quantities. While cross-phase between the density and temperature might not be directly linked to the transport, it can provide information on the relative changes of turbulent properties with changing plasma parameters and...
The poloidal correlation reflectometer (PCR) diagnostic on Wendelstein 7-X (W7-X)[1,2] is two-frequency system covering the Ka- and U-bands comprised of four receiving antennas and a single transmitting antenna. This diagnostic measures plasma density fluctuations in close proximity to two correlation radiometry antennas (CECE)[3] and two Doppler reflectometer systems (DBS)[4]. The PCR on W7-X...
For the first time quasi coherent modes (QC-modes) are detected at the isodynamic stellarator W7-X. QC-modes are known from many tokamak experiments. They appear mostly in the plasma core at low collisionallity and some times in the plasma edge. They show up as density fluctuations in the power spectra, as structures with centre frequency ranging from $40\,$kHz$ \le f_c\le 120\,$kHz. Whereas...
For the Wendelstein 7-X operation phase OP2.1 the Doppler-reflectometry (DR) systems have been upgraded significantly. Steerable mirrors allow for beam steering perpendicular to the local magnetic ๏ฌeld to enhance the measured $k_\perp$-range and to investigate ๏ฌow asymmetries and the poloidal localization of microinstabilities. The operation of three synced DR systems with ordinary mode...
This work concerns a newly created database of plasmas from the most recent operational phase of Wendelstein 7-X (October 2022 โ April 2023). This database includes a comprehensive assortment of various plasma configurations, densities and heating schemes, for which profiles of the radial electric field ($E_{\rm r}$) and the back-scattered power ($S$) were measured using the V-band DR system...
The standard heating method at W7-X is a steady state capable electron cyclotron resonance heating system with ten 140 GHz gyrotrons and an overall installed power of currently 8.3 MW. The fully quasi-optical transmission line to the plasma vessel is the first of its kind. It consists of a section with single beam waveguide (SBWG) mirrors matching the non-perfect Gaussian beam of the gyrotrons...
W7-X is currently equipped with two ECE diagnostics: a 32 channel heterodyne radiometer measuring X2 mode from 120-160 GHz corresponding to a central magnetic field of 2.5 T with a spatial resolution of 1-2 cm behind cold resonance position and a temporal resolution in the order of $ \mu $s, and a Michelson interferometer measuring the higher ECE harmonics in the spectral range of 50-500 GHz...
KSTAR Doppler reflectometer is designed based on 32-channel frequency steering phased array antenna (FSPAA) operating in X-mode over the entire V-band (50-75 GHz). In the FSPAA system, the microwave radiation angle can be changed quickly without mechanical movement. This is a very attractive advantage in a fusion reactor environments where the plasma fluctuates continuously and the concept of...
The simultaneous oscillation of multiple frequencies and the use of a phased array antenna make it possible to measure the instantaneous radial distribution of the wavenumber spectrum S(k, t, r). To realize this, we are developing the phased array antenna which is additive manufactured by a 3D metal printer. In particular, with regard to surface treatment, we have succeeded in...
Turbulence and flows play a key role in tokamak plasmas performance.
The aim of the present contribution is to gain insight into the nature of the instability at the origin of the turbulence and its impact on the flow by studying the dynamics of the density fluctuations and by identifying the contribution coming from the โphase velocityโ of the density fluctuations. Doppler backscattering...
A Doppler backscattering (DBS) diagnostic from LPP has been installed recently on TCV, enabling an extended characterization of the detailed edge $E_r$ structure on this tokamak. The DBS system consists of two continuous wave, independent V-band channels. It uses a quasi-optical launcher antenna[1], shared with TCVโs short-pulse reflectometry system. The polarization can be changed flexibly...
Edge Localized Modes (ELMs) have been associated with precursor oscillations that grow in amplitude leading to the ELM crash. However, the presence and characteristics of these precursors vary significantly across different tokamaks, ELM types, and plasma conditions. In ASDEX Upgrade, for example, the conditions for detecting magnetic precursors remain unclear. Nevertheless, signatures of ELM...
The W-band tunable 7-channel Comb reflectometer (P. A. Molina Cabrera et al., Rev. Sci. Instrum. 94, 083504 (2023)) is used for simultaneous measurements of Doppler backscattering (DBS) spectra at several radial locations in ASDEX Upgrade, enabling the study of dynamical events such as the L-H transition. To facilitate the analysis of the resulting large volume of spectra from short time...
This work presents the development and application of an advanced engineering design workflow for the planning, design, and assessment of future fusion plasma diagnostics. The workflow leverages advanced simulation techniques and synthetic diagnostics for system performance evaluation and prediction, crucial in the decision-making process of the design cycle. A key component of this workflow...
Under the framework of an enabling research EUROfusion project, it was possible to explore the concept of ยตwave tomograph based on the Plasma Positioning Reflectometers (PPR) system planned to measure the plasma shape in a DEMO poloidal cross section from the early start-up phase to flat top and then the ramp-down phase. The possibility to do it in real-time is also considered based on the use...
Reflectometry, compatible with a full grade reactor implementation, has been proposed as a source of real-time (RT) plasma position and shape measurements for control purposes, in replacement or complement of standard magnetic measurements, to ensure reliability and safety on the machine. This new control technique, based on multiple, poloidally distributed, non-magnetic measurements, must be...
A novel multichannel Doppler backscattering (DBS) system based on a comb generator has been designed and tested for application on the HL-3 tokamak. DBS diagnostic is widely used to measure the localized density fluctuations and the propagation velocity of turbulent structures[1-4]. Microwave is launched at a frequency that approaches a cutoff layer in the plasma and at an angle that is...
