ITER perspective on fusion reactor diagnostics—A spectroscopic view

Bock, M. F. M. de; Barnsley, R.; Bassan, M.; Bertalot, L.; Brichard, B.; Bukreev, I.M.; Drevon, J.-M.; Guern, F. Le; Hutton, R.; Ivantsivskiy, M.; Lee, H. G.; Leipold, F.; Maquet, P.; Marot, L.; Martin, Vincent; Mertens, Philippe; Mokeev, A.N.; Moser, L.; Mukhin, E. E.; Pak, S.; Razdobarin, A. G.; Reichle, R.; Seon, C. R.; Seyvet, F.; Simrock, S.; Udintsev, V. S.; Vayakis, G.; Vorpahl, C.

doi:10.1088/1748-0221/11/08/p08010

Cited by 9 publications

(9 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…figure5 and fits well to the reflectivity of P1-1 after cleaning. The diffusive component of the reflectivity increased by 1% at most (see figure5), which is expected due to the nanocrystallinity of the Mo surface (no preferential sputtering of the various crystal orientations in contrast to polycrystalline materials).…”

supporting

confidence: 72%

“…mainly beryllium (Be) [2,3]. More than 20 optical diagnostics, operating in the UV/Vis range, are directly affected by this phenomena and will require mirror surface recovery techniques, currently foreseen in in situ plasma sputtering [4,5]. The removal of these deposits in order to increase the lifetime of the FMs has seen significant progress over the past years [6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Investigation and plasma cleaning of first mirrors coated with relevant ITER contaminants: beryllium and tungsten

et al. 2017

Self Cite

View full text Add to dashboard Cite

In order to extend the investigation of the plasma cleaning of ITER first mirrors, a set of molybdenum mirrors was coated in a laboratory with ITER-relevant contaminants, namely beryllium and tungsten. Different coating techniques as well as several contaminant compositions were used to ensure a large variety of films to clean, completing a previous study conducted on mirrors exposed in the JET ITER-like wall (tokamak deposits) [1]. Due to the toxicity of beryllium, the samples were treated in a vacuum chamber specially built for this purpose. The cleaning was performed using capacitively coupled RF plasma and evaluated by performing reflectivity measurements, scanning electron microscopy, x-ray photoelectron spectroscopy and ion beam analysis. The removal of all types of contaminants was achieved by using different plasma compositions (argon, helium and mixtures of the two) with various ion energies (from 200-600 eV) and in some cases the mirror's reflectivity was restored towards initial values. Pure helium discharges were capable of removing mixed beryllium/ tungsten layers and oxidized molybdenum. In addition, no significant increase in the diffuse reflectivity of the mirrors was observed for the helium cleaning, though this was the case for some samples cleaned with argon. Helium is therefore appropriate for cleaning all mirrors in ITER leading to a possible cleaning regime where the entire vessel is filled with He and all mirrors are cleaned simultaneously without damaging their surfaces.

show abstract

supporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Investigation and plasma cleaning of first mirrors coated with relevant ITER contaminants: beryllium and tungsten

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…FMs have to operate in extreme conditions since they will be exposed to intense UV and x-ray radiation (∼up to 500 kW m −2 ), neutron heating (∼up to 8 W cm −3 ), γ rays, and particle fluxes arising from charge exchange atoms (CXA) up to 2 • 10 19 particles m −2 s −1 with energies up to several keV [2]. In this harsh environment, FMs must maintain their optical properties to be used as reliable tool to control plasma parameters [3][4][5]. A change of FMs reflectivity can lead to a failure of the related diagnostic systems and a consequent impact on the reactor operability.…”

Section: Introductionmentioning

confidence: 99%

The effect of surface temperature on optical properties of molybdenum mirrors in the visible and near-infrared domains

et al. 2018

View full text Add to dashboard Cite

Molybdenum mirrors will be used in several optical diagnostics to control the plasma in the ITER tokamak. In this harsh environment, mirrors can undergo transient temperature rises. Thus the knowledge of the temperature dependence of optical properties of molybdenum is necessary for a good operation of optical systems in ITER. Molybdenum optical properties have been extensively studied at room temperature, but little has been done at high temperatures in the visible and near-infrared domains. We investigate here the temperature dependence of molybdenum reflectivity from the ambient to high temperatures (<800 K) in the 500-1050 nm spectral range. Experimental measurements of reflectivity, performed via a spectroscopic system coupled with laser remote heating, show a maximum increase of 2.5 % at 800 K in the 850-900 nm wavelength range and a non-linear temperature dependency as a function of wavelength. We describe these dependencies through a Fresnel and a Lorentz-Drude model. The Fresnel model accurately reproduces the experimental curve at a given temperature by using a parabolic temperature dependency for the refractive index, n, and a linear dependency for the extinction coefficient, k. We develop a Lorentz-Drude model to describe the interaction of light with charge carriers in the solid. This model includes temperature dependency on both intraband (Drude) and interband (Lorentz) transitions. It is able to reproduce the experimental results quantitatively, highlighting a non-trivial dependency of interband transitions on temperature. Eventually, we use the Lorentz-Drude model to evaluate the total emissivity of molybdenum from 300 K to 2800 K, and we compare our experimental and theoretical findings with previous results.

show abstract

“…Highly advanced, integrated spectroscopic diagnostic systems are implemented on all existing MCF machines without exceptions. The international tokamak ITER will have more than a dozen spectrometers covering near-infrared, visible, vacuum ultraviolet, and soft and hard x-ray ranges in order to fully characterize its plasma condition and evolution [171]. In the next generation tokamak DEMO, the emphasis of spectral measurements is expected to shift towards plasma condition control rather than research, yet the suite of spectroscopic instruments will be extensive.…”

Section: National Institute Of Standards and Technology United States...mentioning

confidence: 99%

Roadmap on photonic, electronic and atomic collision physics: II. Electron and antimatter interactions

Schippers

Sokell

Aumayr

et al. 2019

J. Phys. B: At. Mol. Opt. Phys.

View full text Add to dashboard Cite

We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of the ICPEAC conference. In Roadmap II we focus on electron and antimatter interactions. Modern theoretical and experimental approaches provide detailed insight into the many body quantum dynamics of leptonic collisions with targets of varying complexity ranging from neutral and charged atoms to large biomolecules and clusters. These developments have been driven by technological progress and by the needs of adjacent areas of science such as astrophysics, plasma physics and radiation biophysics. This Roadmap aims at looking back along the road, explaining the evolution of the field, and looking forward, collecting contributions from eighteen leading groups from the field.

show abstract

ITER perspective on fusion reactor diagnostics—A spectroscopic view

Cited by 9 publications

References 14 publications

Investigation and plasma cleaning of first mirrors coated with relevant ITER contaminants: beryllium and tungsten

Investigation and plasma cleaning of first mirrors coated with relevant ITER contaminants: beryllium and tungsten

The effect of surface temperature on optical properties of molybdenum mirrors in the visible and near-infrared domains

Roadmap on photonic, electronic and atomic collision physics: II. Electron and antimatter interactions

Contact Info

Product

Resources

About