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Plasma Diagnostics

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Remote Sensors".

Deadline for manuscript submissions: closed (28 April 2023) | Viewed by 27479

Special Issue Editor

Dr. Bruno Goncalves

E-Mail Website
Guest Editor
Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
Interests: nuclear fusion; plasma diagnostics; control and data acquisition; plasma physics

Special Issue Information

Dear Colleagues,

Plasma Science and Engineering is a multidisciplinary area encompassing some of the most exciting fundamental and applied research themes in today's scientific landscape, with an extraordinarily broad impact in science, technology and industry. Although the mainstream areas of plasma research are readily identified as Fusion (magnetic and inertial), Laser–Plasma Interactions and Low-temperature Plasma Technologies, plasma science is often a key component of many other disciplines, including nanoscience, atomic and molecular physics, surface physics, biophysics, astrophysics and space science.

The measurement of the parameters of plasmas, usually termed as plasma diagnostics, is a key challenge in all of these applications, both for understanding the basic principles as well as, in many cases, for optimization and control of processes. Plasma diagnostics are based on a wide variety of characteristic plasma phenomena and, although most of the techniques used are already well established, plasma diagnostics is still a very challenging and vivid discipline. On one hand, there is continuing effort to attain a better spatial and temporal resolution, to reach higher accuracies and to measure with more spatial channels. On the other hand, diagnostic techniques based on more subtle physical processes (compared to those used in the routine diagnostics) are continuously being developed and new tools are being added (e.g., machine learning techniques). Furthermore, to obtain a better insight in the processes taking place in the plasma, it is a prerequisite that plasma parameters are diagnosed simultaneously, as much as possible, with multi-channel diagnostics, preferably with temporal and spatial resolutions smaller than the typical time and length scales of the instabilities. Furthermore, in some areas, e.g, future fusion reactors, such as ITER and DEMO, there will be a need to measure a wide range of plasma parameters in extreme conditions of temperature, neutron and gamma fluxes while providing inputs to control systems with adequate reliability and long term stability, enabling us to reach and sustain high levels of fusion power in a stationary manner.

This Special Issue will cover the methods, instruments, and experimental techniques used to measure properties of plasma, such as diagnostics for magnetic confinement fusion, beam plasmas and inertial fusion, low-temperature and industrial plasmas, and basic and astrophysical plasmas.

Dr. Bruno Goncalves
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Nuclear instruments and methods for hot plasma diagnostics
  • Plasma diagnostics—charged-particle spectroscopy
  • Plasma diagnostics—interferometry, spectroscopy and imaging
  • Plasma diagnostics—probes
  • Plasma generation (laser-produced, RF, x ray-produced)
  • Plasma diagnostics—simulation
  • Plasma diagnostics—neutral and ion beams
  • Detector design and construction technologies and materials
  • Plasma diagnostics—instrumentation, control and data acquisition
  • Neutron detectors (cold, thermal, fast neutrons)
  • Gamma detectors (scintillators, CZT, HPGe, HgI etc)
  • Plasma diagnostics—high speed photography
  • Data processing methods
  • Detector design and construction technologies and materials
  • Detector alignment and calibration methods.

Published Papers (17 papers)

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Editorial

Jump to: Research, Review

7 pages, 186 KiB  
Editorial
Plasma Diagnostics
by Bruno Gonçalves
Sensors 2024, 24(10), 3257; https://doi.org/10.3390/s24103257 - 20 May 2024
Viewed by 299
Abstract
Plasma science and engineering is a multidisciplinary area encompassing some of the most exciting fundamental and applied research themes in today’s scientific landscape, with an extraordinarily broad impact in science, technology, and industry [...] Full article
(This article belongs to the Special Issue Plasma Diagnostics)

Research

Jump to: Editorial, Review

29 pages, 13959 KiB  
Article
Design and Development of a Diagnostic System for a Non-Intercepting Direct Measure of the SPIDER Ion Source Beamlet Current
by Tommaso Patton, Alastair Shepherd, Basile Pouradier Duteil, Andrea Rigoni Garola, Matteo Brombin, Valeria Candeloro, Gabriele Manduchi, Mauro Pavei, Roberto Pasqualotto, Antonio Pimazzoni, Marco Siragusa, Gianluigi Serianni, Emanuele Sartori, Cesare Taliercio, Paolo Barbato, Vannino Cervaro, Raffaele Ghiraldelli, Bruno Laterza and Federico Rossetto
Sensors 2023, 23(13), 6211; https://doi.org/10.3390/s23136211 - 7 Jul 2023
Cited by 1 | Viewed by 922
Abstract
Stable and uniform beams with low divergence are required in particle accelerators; therefore, beyond the accelerated current, measuring the beam current spatial uniformity and stability over time is necessary to assess the beam performance, since these parameters affect the perveance and thus the [...] Read more.
Stable and uniform beams with low divergence are required in particle accelerators; therefore, beyond the accelerated current, measuring the beam current spatial uniformity and stability over time is necessary to assess the beam performance, since these parameters affect the perveance and thus the beam optics. For high-power beams operating with long pulses, it is convenient to directly measure these current parameters with a non-intercepting system due to the heat management requirement. Such a system needs to be capable of operating in a vacuum in the presence of strong electromagnetic fields and overvoltages, due to electrical breakdowns in the accelerator. Finally, the measure of the beam current needs to be efficiently integrated into a pulse file with the other relevant plant parameters to allow the data analyses required for beam optimization. This paper describes the development, design and commissioning of such a non-intercepting system, the so-called beamlet current monitor (BCM), aimed to directly measure the electric current of a particle beam. In particular, the layout of the system was adapted to the SPIDER experiment, the ion source (IS) prototype of the heating neutral beam injectors (HNB) for the ITER fusion reactor. The diagnostic is suitable to provide the electric current of five beamlets from DC up to 10 MHz. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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31 pages, 16759 KiB  
Article
VUV to IR Emission Spectroscopy and Interferometry Diagnostics for the European Shock Tube for High-Enthalpy Research
by Ricardo Grosso Ferreira, Bernardo Brotas Carvalho, Luís Lemos Alves, Bruno Gonçalves, Victor Fernandez Villace, Lionel Marraffa and Mário Lino da Silva
Sensors 2023, 23(13), 6027; https://doi.org/10.3390/s23136027 - 29 Jun 2023
Viewed by 1251
Abstract
The European Shock Tube for High-Enthalpy Research is a new state-of-the-art facility, tailored for the reproduction of spacecraft planetary entries in support of future European exploration missions, developed by an international consortium led by Instituto de Plasmas e Fusão Nuclear and funded by [...] Read more.
The European Shock Tube for High-Enthalpy Research is a new state-of-the-art facility, tailored for the reproduction of spacecraft planetary entries in support of future European exploration missions, developed by an international consortium led by Instituto de Plasmas e Fusão Nuclear and funded by the European Space Agency. Deployed state-of-the-art diagnostics include vacuum-ultraviolet to ultraviolet, visible, and mid-infrared optical spectroscopy setups, and a microwave interferometry setup. This work examines the specifications and requirements for high-speed flow measurements, and discusses the design choices for the main diagnostics. The spectroscopy setup covers a spectral window between 120 and 5000 nm, and the microwave interferometer can measure electron densities up to 1.5 × 1020 electrons/m3. The main design drivers and technological choices derived from the requirements are discussed in detail herein. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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41 pages, 28189 KiB  
Article
Neutronics Simulations for DEMO Diagnostics
by Raul Luís, Yohanes Nietiadi, Antonio Quercia, Alberto Vale, Jorge Belo, António Silva, Bruno Gonçalves, Artur Malaquias, Andrei Gusarov, Federico Caruggi, Enrico Perelli Cippo, Maryna Chernyshova, Barbara Bienkowska and Wolfgang Biel
Sensors 2023, 23(11), 5104; https://doi.org/10.3390/s23115104 - 26 May 2023
Cited by 2 | Viewed by 1274
Abstract
One of the main challenges in the development of a plasma diagnostic and control system for DEMO is the need to cope with unprecedented radiation levels in a tokamak during long operation periods. A list of diagnostics required for plasma control has been [...] Read more.
One of the main challenges in the development of a plasma diagnostic and control system for DEMO is the need to cope with unprecedented radiation levels in a tokamak during long operation periods. A list of diagnostics required for plasma control has been developed during the pre-conceptual design phase. Different approaches are proposed for the integration of these diagnostics in DEMO: in equatorial and upper ports, in the divertor cassette, on the inner and outer surfaces of the vacuum vessel and in diagnostic slim cassettes, a modular approach developed for diagnostics requiring access to the plasma from several poloidal positions. According to each integration approach, diagnostics will be exposed to different radiation levels, with a considerable impact on their design. This paper provides a broad overview of the radiation environment that diagnostics in DEMO are expected to face. Using the water-cooled lithium lead blanket configuration as a reference, neutronics simulations were performed for pre-conceptual designs of in-vessel, ex-vessel and equatorial port diagnostics representative of each integration approach. Flux and nuclear load calculations are provided for several sub-systems, along with estimations of radiation streaming to the ex-vessel for alternative design configurations. The results can be used as a reference by diagnostic designers. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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13 pages, 2025 KiB  
Article
Spectroscopy of Laser-Induced Dielectric Breakdown Plasma in Mixtures of Air with Inert Gases Ar, He, Kr, and Xe
by Andrew Martusevich, Roman Kornev, Artur Ermakov, Igor Gornushkin, Vladimir Nazarov, Lyubov Shabarova and Vladimir Shkrunin
Sensors 2023, 23(2), 932; https://doi.org/10.3390/s23020932 - 13 Jan 2023
Viewed by 1435
Abstract
The generation of ozone and nitrogen oxides by laser-induced dielectric breakdown (LIDB) in mixtures of air with noble gases Ar, He, Kr, and Xe is investigated using OES and IR spectroscopy, mass spectrometry, and absorption spectrophotometry. It is shown that the formation of [...] Read more.
The generation of ozone and nitrogen oxides by laser-induced dielectric breakdown (LIDB) in mixtures of air with noble gases Ar, He, Kr, and Xe is investigated using OES and IR spectroscopy, mass spectrometry, and absorption spectrophotometry. It is shown that the formation of NO and NO2 noticeably depends on the type of inert gas; the more complex electronic configuration and the lower ionization potential of the inert gas led to increased production of NO and NO2. The formation of ozone occurs mainly due to the photolytic reaction outside the gas discharge zone. Equilibrium thermodynamic analysis showed that the formation of NO in mixtures of air with inert gases does not depend on the choice of an inert gas, while the equilibrium concentration of the NO+ ion decreases with increasing complexity of the electronic configuration of an inert gas. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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13 pages, 3018 KiB  
Article
First Results of the Implementation of the Doppler Backscattering Diagnostic for the Investigation of the Transition to H-Mode in the Spherical Tokamak Globus-M2
by Anna Ponomarenko, Alexander Yashin, Gleb Kurskiev, Vladimir Minaev, Alexander Petrov, Yuri Petrov, Nikolay Sakharov and Nikita Zhiltsov
Sensors 2023, 23(2), 830; https://doi.org/10.3390/s23020830 - 11 Jan 2023
Cited by 5 | Viewed by 1283
Abstract
This paper presents the first results of a study of the LH transition on the new spherical Globus-M2 tokamak using the Doppler backscattering (DBS) diagnostic. New data characterizing the H-mode of discharges with higher values of the plasma parameters, such as magnetic field [...] Read more.
This paper presents the first results of a study of the LH transition on the new spherical Globus-M2 tokamak using the Doppler backscattering (DBS) diagnostic. New data characterizing the H-mode of discharges with higher values of the plasma parameters, such as magnetic field Bt up to 0.9 T and plasma current Ip up to 450 kA, were collected and analyzed. An upgraded neutral beam injection (NBI) system was used to initiate the LH transition. DBS allows the measurement of the poloidal rotation velocity and the turbulence amplitude of the plasma. The multi-frequency DBS system installed on Globus-M2 can simultaneously collect data in different areas spanning from the separatrix to the plasma core. This allowed for the radial profiles of the rotation velocity and electric field to be calculated before and after the LH transition. In addition, the values and temporal evolution of the velocity shear were obtained. The associated turbulence suppression after the transition to the H-mode was investigated using DBS. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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26 pages, 15827 KiB  
Article
Modelling of Backscattering off Filaments Using the Code IPF-FD3D for the Interpretation of Doppler Backscattering Data
by Alexander Yashin, Natalia Teplova, Georgiy Zadvitskiy and Anna Ponomarenko
Sensors 2022, 22(23), 9441; https://doi.org/10.3390/s22239441 - 2 Dec 2022
Cited by 3 | Viewed by 998
Abstract
Filaments or blobs are well known to strongly contribute to particle and energy losses both in L- and H-mode, making them an important plasma characteristic to investigate. They are plasma structures narrowly localized across a magnetic field and stretched along magnetic field lines. [...] Read more.
Filaments or blobs are well known to strongly contribute to particle and energy losses both in L- and H-mode, making them an important plasma characteristic to investigate. They are plasma structures narrowly localized across a magnetic field and stretched along magnetic field lines. In toroidal devices, their development is observed to take place in the peripheral plasma. Filament characteristics have been studied extensively over the years using various diagnostic techniques. One such diagnostic is the Doppler backscattering (DBS) method employed at the spherical tokamak Globus-M/M2. It has been observed that the DBS signal reacts to the backscattering from filaments. However, the DBS data have proven difficult to analyze, which is why modelling was undertaken using the code IPF-FD3D to understand what kind of information can be extrapolated from the signals. A circular filament was thoroughly investigated in slab geometry with a variety of characteristics studied. Apart from that, the motion of the filaments in the poloidal and radial directions was analyzed. Additionally, other shapes of filaments were presented in this work. Modelling for the real geometry of the Globus-M/M2 tokamak was performed. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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11 pages, 4077 KiB  
Article
Refined Appearance Potential Mass Spectrometry for High Precision Radical Density Quantification in Plasma
by Chulhee Cho, Sijun Kim, Youngseok Lee, Wonnyoung Jeong, Inho Seong, Jangjae Lee, Minsu Choi, Yebin You, Sangho Lee, Jinho Lee and Shinjae You
Sensors 2022, 22(17), 6589; https://doi.org/10.3390/s22176589 - 31 Aug 2022
Cited by 2 | Viewed by 1388
Abstract
As the analysis of complicated reaction chemistry in bulk plasma has become more important, especially in plasma processing, quantifying radical density is now in focus. For this work, appearance potential mass spectrometry (APMS) is widely used; however, the original APMS can produce large [...] Read more.
As the analysis of complicated reaction chemistry in bulk plasma has become more important, especially in plasma processing, quantifying radical density is now in focus. For this work, appearance potential mass spectrometry (APMS) is widely used; however, the original APMS can produce large errors depending on the fitting process, as the fitting range is not exactly defined. In this research, to reduce errors resulting from the fitting process of the original method, a new APMS approach that eliminates the fitting process is suggested. Comparing the neutral densities in He plasma between the conventional method and the new method, along with the real neutral density obtained using the ideal gas equation, confirmed that the proposed quantification approach can provide more accurate results. This research will contribute to improving the precision of plasma diagnosis and help elucidate the plasma etching process. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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13 pages, 953 KiB  
Article
Development of a Noninvasive Real-Time Ion Energy Distribution Monitoring System Applicable to Collisional Plasma Sheath
by Inho Seong, Sijun Kim, Youngseok Lee, Chulhee Cho, Jangjae Lee, Wonnyoung Jeong, Yebin You and Shinjae You
Sensors 2022, 22(16), 6254; https://doi.org/10.3390/s22166254 - 20 Aug 2022
Cited by 5 | Viewed by 1594
Abstract
As the importance of ion-assisted surface processing based on low-temperature plasma increases, the monitoring of ion energy impinging into wafer surfaces becomes important. Monitoring methods that are noninvasive, real-time, and comprise ion collision in the sheath have received much research attention. However, in [...] Read more.
As the importance of ion-assisted surface processing based on low-temperature plasma increases, the monitoring of ion energy impinging into wafer surfaces becomes important. Monitoring methods that are noninvasive, real-time, and comprise ion collision in the sheath have received much research attention. However, in spite of this fact, most research was performed in invasive, not real-time, and collisionless ion sheath conditions. In this paper, we develop a noninvasive real-time IED monitoring system based on an ion trajectory simulation where the Monte Carlo collision method and an electrical model are adopted to describe collisions in sheaths. We technically, theoretically, and experimentally investigate the IED measurement with the proposed method, and compared it with the result of IEDs measured via a quadrupole mass spectrometer under various conditions. The comparison results show that there was no major change in the IEDs as radio-frequency power increased or the IED gradually became broad as gas pressure increased, which was in a good agreement with the results of the mass spectrometer. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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12 pages, 2408 KiB  
Article
Low-Temperature Plasma Diagnostics to Investigate the Process Window Shift in Plasma Etching of SiO2
by Youngseok Lee, Sijun Kim, Jangjae Lee, Chulhee Cho, Inho Seong and Shinjae You
Sensors 2022, 22(16), 6029; https://doi.org/10.3390/s22166029 - 12 Aug 2022
Cited by 4 | Viewed by 1836
Abstract
As low-temperature plasma plays an important role in semiconductor manufacturing, plasma diagnostics have been widely employed to understand changes in plasma according to external control parameters, which has led to the achievement of appropriate plasma conditions normally termed the process window. During plasma [...] Read more.
As low-temperature plasma plays an important role in semiconductor manufacturing, plasma diagnostics have been widely employed to understand changes in plasma according to external control parameters, which has led to the achievement of appropriate plasma conditions normally termed the process window. During plasma etching, shifts in the plasma conditions both within and outside the process window can be observed; in this work, we utilized various plasma diagnostic tools to investigate the causes of these shifts. Cutoff and emissive probes were used to measure the electron density and plasma potential as indicators of the ion density and energy, respectively, that represent the ion energy flux. Quadrupole mass spectrometry was also used to show real-time changes in plasma chemistry during the etching process, which were in good agreement with the etching trend monitored via in situ ellipsometry. The results show that an increase in the ion energy flux and a decrease in the fluorocarbon radical flux alongside an increase in the input power result in the breaking of the process window, findings that are supported by the reported SiO2 etch model. By extending the SiO2 etch model with rigorous diagnostic measurements (or numerous diagnostic methods), more intricate plasma processing conditions can be characterized, which will be beneficial in applications and industries where different input powers and gas flows can make notable differences to the results. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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16 pages, 4383 KiB  
Article
Development of a High-Linearity Voltage and Current Probe with a Floating Toroidal Coil: Principle, Demonstration, Design Optimization, and Evaluation
by Si-jun Kim, In-ho Seong, Young-seok Lee, Chul-hee Cho, Won-nyoung Jeong, Ye-bin You, Jang-jae Lee and Shin-jae You
Sensors 2022, 22(15), 5871; https://doi.org/10.3390/s22155871 - 5 Aug 2022
Cited by 2 | Viewed by 2019
Abstract
As the conventional voltage and current (VI) probes widely used in plasma diagnostics have separate voltage and current sensors, crosstalk between the sensors leads to degradation of measurement linearity, which is related to practical accuracy. Here, we propose a VI probe with a [...] Read more.
As the conventional voltage and current (VI) probes widely used in plasma diagnostics have separate voltage and current sensors, crosstalk between the sensors leads to degradation of measurement linearity, which is related to practical accuracy. Here, we propose a VI probe with a floating toroidal coil that plays both roles of a voltage and current sensor and is thus free from crosstalk. The operation principle and optimization conditions of the VI probe are demonstrated and established via three-dimensional electromagnetic wave simulation. Based on the optimization results, the proposed VI probe is fabricated and calibrated for the root-mean-square (RMS) voltage and current with a high-voltage probe and a vector network analyzer. Then, it is evaluated through a comparison with a commercial VI probe, with the results demonstrating that the fabricated VI probe achieved a slightly higher linearity than the commercial probe: R2 of 0.9967 and 0.9938 for RMS voltage and current, respectively. The proposed VI probe is believed to be applicable to plasma diagnostics as well as process monitoring with higher accuracy. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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14 pages, 3356 KiB  
Article
Development of the Measurement of Lateral Electron Density (MOLE) Probe Applicable to Low-Pressure Plasma Diagnostics
by Si-jun Kim, Sang-ho Lee, Ye-bin You, Young-seok Lee, In-ho Seong, Chul-hee Cho, Jang-jae Lee and Shin-jae You
Sensors 2022, 22(15), 5487; https://doi.org/10.3390/s22155487 - 22 Jul 2022
Cited by 4 | Viewed by 1620
Abstract
As the importance of measuring electron density has become more significant in the material fabrication industry, various related plasma monitoring tools have been introduced. In this paper, the development of a microwave probe, called the measurement of lateral electron density (MOLE) probe, is [...] Read more.
As the importance of measuring electron density has become more significant in the material fabrication industry, various related plasma monitoring tools have been introduced. In this paper, the development of a microwave probe, called the measurement of lateral electron density (MOLE) probe, is reported. The basic properties of the MOLE probe are analyzed via three-dimensional electromagnetic wave simulation, with simulation results showing that the probe estimates electron density by measuring the surface wave resonance frequency from the reflection microwave frequency spectrum (S11). Furthermore, an experimental demonstration on a chamber wall measuring lateral electron density is conducted by comparing the developed probe with the cutoff probe, a precise electron density measurement tool. Based on both simulation and experiment results, the MOLE probe is shown to be a useful instrument to monitor lateral electron density. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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14 pages, 5816 KiB  
Article
Affect of Secondary Beam Non-Uniformity on Plasma Potential Measurements by HIBD with Split-Plate Detector
by Igor Nedzelskiy, Artur Malaquias, Rafael Henriques and Ridhima Sharma
Sensors 2022, 22(14), 5135; https://doi.org/10.3390/s22145135 - 8 Jul 2022
Viewed by 1231
Abstract
In a Heavy Ion Beam Diagnostic (HIBD), the plasma potential is obtained by measuring the energy of the secondary ions resulting from beam-plasma collisions by an electrostatic energy analyzer with split-plate detector (SPD), which relates the secondary ion beam energy variation to its [...] Read more.
In a Heavy Ion Beam Diagnostic (HIBD), the plasma potential is obtained by measuring the energy of the secondary ions resulting from beam-plasma collisions by an electrostatic energy analyzer with split-plate detector (SPD), which relates the secondary ion beam energy variation to its position determined by the difference in currents between the split plates. Conventionally, the data from SPD are analyzed with the assumption that the secondary beam current is uniform. However, the secondary beam presents an effective projection of the primary beam, the current of which, as a rule, has a bell-like non-uniform profile. This paper presents: (i) the general features of the secondary beam profile formation, considered in the simplistic approximation of the circular primary beam and the secondary ions that emerge orthogonal to the primary beam axis, (ii) details of spit-plate detection and the influence of the secondary beam non-uniformity on plasma potential measurements, (iii) supported experimental data from the tokamak ISTTOK HIBD for primary and secondary beam profiles and the SPD transfer characteristic, obtained for the 90° cylindrical energy analyzer (90° CEA) and (iv) the implementation of a multiple cell array detector (MCAD) with dedicated resolution for the measurements of secondary beam profile and MCAD operation in multi-split-plate detection mode for direct measurements of the SPD transfer characteristic. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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28 pages, 10527 KiB  
Article
The Heavy-Ion Beam Diagnostic of the ISTTOK Tokamak—Highlights and Recent Developments
by A. Malaquias, I. S. Nedzelskiy, R. Henriques and R. Sharma
Sensors 2022, 22(11), 4038; https://doi.org/10.3390/s22114038 - 26 May 2022
Cited by 3 | Viewed by 1369
Abstract
The unique arrangement of the heavy-ion beam diagnostic in ISTTOK enables one to measure the evolution of temperature, density and pressure-like profiles in normal and AC discharges. The fast chopping beam technique provided the possibility to reduce the noise on the measurements of [...] Read more.
The unique arrangement of the heavy-ion beam diagnostic in ISTTOK enables one to measure the evolution of temperature, density and pressure-like profiles in normal and AC discharges. The fast chopping beam technique provided the possibility to reduce the noise on the measurements of the plasma pressure-like profile and for the precise control of the plasma column position in real time. The consequent improvements in S/N levels allowed the observation of the effects of runaway beam magnetic energy conversion into plasma local heating. In addition, it made it possible to follow the evolution of the quiescent plasma maintained during AC transitions when the plasma current is null. The use of a new operation mode in the cylindrical energy analyzer provided an improved resolution up to five times in determining the fluctuations of the plasma potential as compared to the normal operation mode. Such analyzer is extremely compact (250 mm × 250 mm × 120 mm) and provides a unique geometry in order to cover the whole plasma diameter. The detector configuration choice gives the possibility for the simultaneous measurements of plasma poloidal magnetic field, plasma pressure-like and plasma potential profiles together with their fluctuations. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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13 pages, 2007 KiB  
Article
Angular-Resolved Thomson Parabola Spectrometer for Laser-Driven Ion Accelerators
by Carlos Salgado-López, Jon Imanol Apiñaniz, José Luis Henares, José Antonio Pérez-Hernández, Diego de Luis, Luca Volpe and Giancarlo Gatti
Sensors 2022, 22(9), 3239; https://doi.org/10.3390/s22093239 - 22 Apr 2022
Cited by 5 | Viewed by 2907
Abstract
This article reports the development, construction, and experimental test of an angle-resolved Thomson parabola (TP) spectrometer for laser-accelerated multi-MeV ion beams in order to distinguish between ionic species with different charge-to-mass ratio. High repetition rate (HHR) compatibility is guaranteed by the use of [...] Read more.
This article reports the development, construction, and experimental test of an angle-resolved Thomson parabola (TP) spectrometer for laser-accelerated multi-MeV ion beams in order to distinguish between ionic species with different charge-to-mass ratio. High repetition rate (HHR) compatibility is guaranteed by the use of a microchannel plate (MCP) as active particle detector. The angular resolving power, which is achieved due to an array of entrance pinholes, can be simply adjusted by modifying the geometry of the experiment and/or the pinhole array itself. The analysis procedure allows for different ion traces to cross on the detector plane, which greatly enhances the flexibility and capabilities of the detector. A full characterization of the TP magnetic field is implemented into a relativistic code developed for the trajectory calculation of each pinhole beamlet. We describe the first test of the spectrometer at the 1PW VEGA 3 laser facility at CLPU, Salamanca (Spain), where up to 15MeV protons and carbon ions from a 3μm laser-irradiated Al foil are detected. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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13 pages, 707 KiB  
Article
Uncertainties in Atomic Data for Modeling Astrophysical Charge Exchange Plasmas
by Liyi Gu, Chintan Shah and Ruitian Zhang
Sensors 2022, 22(3), 752; https://doi.org/10.3390/s22030752 - 19 Jan 2022
Cited by 10 | Viewed by 1735
Abstract
Relevant uncertainties of theoretical atomic data are vital to determining the accuracy of plasma diagnostics in a number of areas, including, in particular, the astrophysical study. We present a new calculation of the uncertainties on the present theoretical ion-impact charge exchange atomic data [...] Read more.
Relevant uncertainties of theoretical atomic data are vital to determining the accuracy of plasma diagnostics in a number of areas, including, in particular, the astrophysical study. We present a new calculation of the uncertainties on the present theoretical ion-impact charge exchange atomic data and X-ray spectra, based on a set of comparisons with the existing laboratory data obtained in historical merged-beam, cold-target recoil-ion momentum spectroscopy, and electron beam ion traps experiments. The average systematic uncertainties are found to be 35–88% on the total cross sections, and 57–75% on the characteristic line ratios. The model deviation increases as the collision energy decreases. The errors on total cross sections further induce a significant uncertainty to the calculation of ionization balance for low-temperature collisional plasmas. Substantial improvements of the atomic database and dedicated laboratory measurements are needed to obtain the current models, ready for the X-ray spectra from the next X-ray spectroscopic mission. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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Review

Jump to: Editorial, Research

32 pages, 15537 KiB  
Review
Advances, Challenges, and Future Perspectives of Microwave Reflectometry for Plasma Position and Shape Control on Future Nuclear Fusion Devices
by Bruno Gonçalves, Paulo Varela, António Silva, Filipe Silva, Jorge Santos, Emanuel Ricardo, Alberto Vale, Raúl Luís, Yohanes Nietiadi, Artur Malaquias, Jorge Belo, José Dias, Jorge Ferreira, Thomas Franke, Wolfgang Biel, Stéphane Heuraux, Tiago Ribeiro, Gianluca De Masi, Onofrio Tudisco, Roberto Cavazzana, Giuseppe Marchiori and Ocleto D’Arcangeloadd Show full author list remove Hide full author list
Sensors 2023, 23(8), 3926; https://doi.org/10.3390/s23083926 - 12 Apr 2023
Cited by 6 | Viewed by 2711
Abstract
Providing energy from fusion and finding ways to scale up the fusion process to commercial proportions in an efficient, economical, and environmentally benign way is one of the grand challenges for engineering. Controlling the burning plasma in real-time is one of the critical [...] Read more.
Providing energy from fusion and finding ways to scale up the fusion process to commercial proportions in an efficient, economical, and environmentally benign way is one of the grand challenges for engineering. Controlling the burning plasma in real-time is one of the critical issues that need to be addressed. Plasma Position Reflectometry (PPR) is expected to have an important role in next-generation fusion machines, such as DEMO, as a diagnostic to monitor the position and shape of the plasma continuously, complementing magnetic diagnostics. The reflectometry diagnostic uses radar science methods in the microwave and millimetre wave frequency ranges and is envisaged to measure the radial edge density profile at several poloidal angles providing data for the feedback control of the plasma position and shape. While significant steps have already been given to accomplish that goal, with proof of concept tested first in ASDEX-Upgrade and afterward in COMPASS, important, ground-breaking work is still ongoing. The Divertor Test Tokamak (DTT) facility presents itself as the appropriate future fusion device to implement, develop, and test a PPR system, thus contributing to building a knowledge database in plasma position reflectometry required for its application in DEMO. At DEMO, the PPR diagnostic’s in-vessel antennas and waveguides, as well as the magnetic diagnostics, may be exposed to neutron irradiation fluences 5 to 50 times greater than those experienced by ITER. In the event of failure of either the magnetic or microwave diagnostics, the equilibrium control of the DEMO plasma may be jeopardized. It is, therefore, imperative to ensure that these systems are designed in such a way that they can be replaced if necessary. To perform reflectometry measurements at the 16 envisaged poloidal locations in DEMO, plasma-facing antennas and waveguides are needed to route the microwaves between the plasma through the DEMO upper ports (UPs) to the diagnostic hall. The main integration approach for this diagnostic is to incorporate these groups of antennas and waveguides into a diagnostics slim cassette (DSC), which is a dedicated complete poloidal segment specifically designed to be integrated with the water-cooled lithium lead (WCLL) breeding blanket system. This contribution presents the multiple engineering and physics challenges addressed while designing reflectometry diagnostics using radio science techniques. Namely, short-range dedicated radars for plasma position and shape control in future fusion experiments, the advances enabled by the designs for ITER and DEMO, and the future perspectives. One key development is in electronics, aiming at an advanced compact coherent fast frequency sweeping RF back-end [23–100 GHz in few μs] that is being developed at IPFN-IST using commercial Monolithic Microwave Integrated Circuits (MMIC). The compactness of this back-end design is crucial for the successful integration of many measurement channels in the reduced space available in future fusion machines. Prototype tests of these devices are foreseen to be performed in current nuclear fusion machines. Full article
(This article belongs to the Special Issue Plasma Diagnostics)
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