The use of an injected neutral beam—either a dedicated diagnostic beam or the main heating beams—to localize and enhance plasma spectroscopic measurements can be exploited for a number of key physics issues in magnetic confinement fusion research, yielding detailed profile information on thermal and fast ion parameters, the radial electric field, plasma current density, and turbulent transport. The ability to make these measurements has played a significant role in much of our recent progress in the scientific understanding of fusion plasmas. The measurements can utilize emission from excited state transitions either from plasma ions or from the beam atoms themselves. The primary requirement is that the beam “probe” interacts with the plasma in a known fashion. Advantages of active spectroscopy include high spatial resolution due to the enhanced localization of the emission and the use of appropriate imaging optics, background rejection through the appropriate modulation and timing of the beam and emissio...

Beams, brightness, and background: Using active spectroscopy techniques for precision measurements in fusion plasma researcha)

Charge-transfer $n$ partial cross sections have been calculated for collisions of ${\mathrm{Be}}^{4+}$ with $\mathrm{H}(1s)$ by means of a versatile lattice method that is applicable in a wide energy range (between 1 and 500 keV/u). The cross sections, which include up to the high-lying $n=8$ level, are compared to existing semiclassical calculations in order to quantify the accuracy of the results. The reliability of the lattice method at high impact energies is confirmed by comparison with classical trajectory Monte Carlo calculations. It is found that the $n$ partial cross sections larger than ${10}^{\ensuremath{-}18} {\mathrm{cm}}^{2}$, calculated using the lattice method, agree with differences smaller than 15% with those from the method considered the most accurate at each energy. The calculation yields as well accurate total electron capture cross sections, which are studied in detail at $E=100$ keV/u to obtain a converged value.

/pdf/application-of-a-grid-numerical-method-to-calculate-state-2vln06vul1.pdf

Application of a grid numerical method to calculate state-selective cross sections for electron capture in Be 4 + +H (1 s ) collisions

A feasibility study for the use of core charge exchange recombination spectroscopy on ITER has shown that accurate measurements on the helium ash require a spectrometer with a high etendue of 1mm 2sr to comply with the measurement requirements [S. Tugarinov, Rev. Sci. Instrum. 74, 2075 (2003)]10.1063/1.1537443. To this purpose such an instrument has been developed consisting of three separate wavelength channels (to measure simultaneously He/Be, C/Ne, and H/D/T together with the Doppler shifted direct emission of the diagnostic neutral beam, the beam emission (BES) signal), combining high dispersion (0.02 nm/pixel), sufficient resolution (0.2 nm), high efficiency (55%), and extended wavelength range (14 nm) at high etendue. The combined measurement of the BES along the same sightline within a third wavelength range provides the possibility for in situ calibration of the charge eXchange recombination spectroscopy signals. In addition, the option is included to use the same instrument for measurements of the fast fluctuations of the beam emission intensity up to 2 MHz, with the aim to study MHD activity. © 2012 American Institute of Physics.

/pdf/a-high-etendue-spectrometer-suitable-for-core-charge-24s6iomy7z.pdf

A high etendue spectrometer suitable for core charge eXchange recombination spectroscopy on ITER.

The CXRS (Charge-eXchange Recombination Spectroscopy) diagnostic for the core plasma of ITER will be designed to provide observation of the dedicated diagnostic beam (DNB) over a wide radial range, roughly from a normalised radius r/a = 07 to close to the plasma axis The collected light will be transported through the Upper Port Plug #3 (UPP3) to a bundle of fibres and ultimately to a set of remote spectrometers The design is particularly challenging in view of the ITER environment of particle, heat and neutron fluxes, temperature cycles, electromagnetic loads, vibrations, expected material degradation and fatigue, constraints against tritium penetration, integration in the plug and limited opportunities for maintenance Moreover, a high performance (etendue × transmission, dynamic range) is expected for the port plug system since the beam attenuation is large and the background light omnipresent, especially in terms of bremsstrahlung, line radiation and reflections The present contribution will give an overview of the current status and activities which deal with the core CXRS system, summarising the investigations which have taken place before entering the actual development and design phase

/pdf/status-of-the-r-d-activities-to-the-design-of-an-iter-core-48zinzhvbx.pdf

Status of the R&D activities to the design of an ITER core CXRS diagnostic system

The Doppler Shift Spectroscopy (DSS) diagnostic is in the conceptual stage to estimate beam divergence, stripping losses, and beam uniformity of the 100 keV hydrogen Diagnostics Neutral Beam of International Thermonuclear Experimental Reactor. This DSS diagnostic is used to measure the above-mentioned parameters with an error of less than 10%. To aid the design calculations and to establish a methodology for estimation of the beam divergence, DSS measurements were carried out on the existing prototype ion source RF Operated Beam Source in India for Negative ion Research. Emissions of the fast-excited neutrals that are generated from the extracted negative ions were collected in the target tank, and the line broadening of these emissions were used for estimating beam divergence. The observed broadening is a convolution of broadenings due to beam divergence, collection optics, voltage ripple, beam focusing, and instrumental broadening. Hence, for estimating the beam divergence from the observed line broadening, a systematic line profile analysis was performed. To minimize the error in the divergence measurements, a study on error propagation in the beam divergence measurements was carried out and the error was estimated. The measurements of beam divergence were done at a constant RF power of 50 kW and a source pressure of 0.6 Pa by varying the extraction voltage from 4 kV to10 kV and the acceleration voltage from 10 kV to 15 kV. These measurements were then compared with the calorimetric divergence, and the results seemed to agree within 10%. A minimum beam divergence of ∼3° was obtained when the source was operated at an extraction voltage of ∼5 kV and at a ∼10 kV acceleration voltage, i.e., at a total applied voltage of 15 kV. This is in agreement with the values reported in experiments carried out on similar sources elsewhere.

Evaluation of beam divergence of a negative hydrogen ion beam using Doppler shift spectroscopy diagnostics

Overview on R&D and design activities for the ITER core charge exchange spectroscopy diagnostic system

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

R. Voinchet

Author Tools

Chat about Author

Papers

Overview on R&D and design activities for the ITER core charge exchange spectroscopy diagnostic system