Development of atomic beam probe for tokamaks

Berta, M.; Anda, G.; Aradi, M.; Bencze, A.; Buday, Cs; Kiss, I.; Tulipán, S.; Veres, G. I.; Zoletnik, S.; Havlíček, Jan; Hacek, P.

doi:10.1016/j.fusengdes.2013.05.064

Cited by 12 publications

(7 citation statements)

References 11 publications

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“…18 It has to be mentioned that the diagnostic can be extended to measure plasma edge current and potential fluctuations. 19,20 On JET, besides the Li-BES diagnostic, several other methods are available for the measurement of the edge density profile. The high resolution Thomson scattering 21 a) See the author list of "Overview of the JET results in support to ITER," by X. Litaudon et al, to be published in Nuclear Fusion Special issue: Overview and summary reports from the 26th Fusion Energy Conference (Kyoto, Japan, 17-22 October 2016).…”

Section: Introductionmentioning

confidence: 99%

Sub-millisecond electron density profile measurement at the JET tokamak with the fast lithium beam emission spectroscopy system

Réfy

Brix

Gomes

et al. 2018

Review of Scientific Instruments

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Diagnostic alkali atom (e.g., lithium) beams are routinely used to diagnose magnetically confined plasmas, namely, to measure the plasma electron density profile in the edge and the scrape off layer region. A light splitting optics system was installed into the observation system of the lithium beam emission spectroscopy diagnostic at the Joint European Torus (JET) tokamak, which allows simultaneous measurement of the beam light emission with a spectrometer and a fast avalanche photodiode (APD) camera. The spectrometer measurement allows density profile reconstruction with ∼10 ms time resolution, absolute position calculation from the Doppler shift, spectral background subtraction as well as relative intensity calibration of the channels for each discharge. The APD system is capable of measuring light intensities on the microsecond time scale. However ∼100 μs integration is needed to have an acceptable signal to noise ratio due to moderate light levels. Fast modulation of the beam up to 30 kHz is implemented which allows background subtraction on the 100 μs time scale. The measurement covers the 0.9 < ρ < 1.1 range with 6-10 mm optical resolution at the measurement location which translates to 3-5 mm radial resolution at the midplane due to flux expansion. An automated routine has been developed which performs the background subtraction, the relative calibration, and the comprehensive error calculation, runs a Bayesian density reconstruction code, and loads results to the JET database. The paper demonstrates the capability of the APD system by analyzing fast phenomena like pellet injection and edge localized modes.

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Section: Introductionmentioning

confidence: 99%

Sub-millisecond electron density profile measurement at the JET tokamak with the fast lithium beam emission spectroscopy system

Réfy

Brix

Gomes

et al. 2018

Review of Scientific Instruments

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“…With this components the i-HIBP is based on well developed technologies and more compact than classical HIBPs. It is therefore very similar to the atomic beam probe concept realized at the COMPASS tokamak [15]. In comparison to electrical multi-cell array detectors [11,15], which are able to directly measure the ion current without introducing additional complications of an optical conversion, the use of a scintillator with an optical detector system has the advantage of a high spatial resolution just limited by the grain size of the scintillator material or the resolution of the optical system while keeping the ability to measure signals down to a few 100 pA/mm 2 due to the amplification effect of the scintillator [16].…”

Section: Introductionmentioning

confidence: 65%

mentioning

confidence: 64%

“…In comparison to electrical multi-cell array detectors [10,14], which are able to directly measure the ion current without introducing additional complications of an optical conversion, the use of a scintillator with an optical detector system has the advantage of a high spatial resolution just limited by the grain size of the scintillator material or the resolution of the optical system while keeping the ability to measure signals down to a few 100 pA/mm 2 due to the amplification effect of the scintillator [15]. The basic principle of the i-HIBP is shown in figure 1 on the left.…”

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Beam modelling and hardware design of an imaging heavy ion beam probe for ASDEX Upgrade

et al. 2019

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The imaging heavy ion beam probe (i-HIBP) developed at the ASDEX Upgrade tokamak is a new diagnostic concept for investigations at the edge of high temperature plasmas. By means of a heavy alkali beam injector, a neutral primary beam of an energy of 70 keV is injected into the fusion plasma, where it is ionized generating a fan of secondary beams. These are deflected by the magnetic field of the tokamak and intersect a scintillator plate in the limiter shadow of the tokamak. The light pattern on the scintillator detected with a high speed camera contains radial information on the density, electrostatic potential and the magnetic field in the edge region of the plasma. For the design of the i-HIBP, a detailed beam model including the 3D tokamak magnetic field and beam attenuation effects for cesium and rubidium atoms is developed in order to find the optimum injection scheme within the limited space of the tokamak environment for maximum 1Corresponding author.

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“…If the Larmor radius is large enough the ions can be collected outside the plasma and from their toroidal deflection some information can be gained on the poloidal field. With Lithium ions the method is usable only in small devices 40 and low magnetic fields but with heavier Alkali ions the edge region of medium-size fusion experiments can also be diagnosed 41 . As the toroidal deflection is in the few cm range the beam diameter should be limited to a few mm where the beam current is in the 100 µA range.…”

Section: Atomic Beam Probementioning

confidence: 99%

Advanced neutral alkali beam diagnostics for applications in fusion research (invited)

Zoletnik

Anda

Aradi

et al. 2018

Review of Scientific Instruments

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Diagnosing the density profile at the edge of high temperature fusion plasmas by accelerated Lithium beam is a known technique since decades. By knowledge of the relevant atomic physics rate coefficients the plasma electron density profile can be calculated from the relatively calibrated light profile along the beam. Several additional possibilities have already been demonstrated: CXRS for ion temperature/flow, Zeeman polarimetry for edge plasma current; therefore the Li-beam diagnostic offers a wealth of information at the plasma edge. The weaknesses of the method are the relatively faint light signal, background light and technical difficulties of the beam injector which usually seriously limit the applicability. In this talk we present systematic developments in alkali-beam diagnostics (Li, Na) both for the injector, observation system and detectors which resulted in strongly increased capabilities. Advanced systems have been built and microsecond scale density profile, turbulence and zonal flow measurement demonstrated. A novel edge current measurement technique has also been designed and components tested with potentially microsecond-scale time resolution. Additional possibilities of these advanced systems for spectral measurements (CXRS, various Zeeman schemes) are also discussed.

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Development of atomic beam probe for tokamaks

Cited by 12 publications

References 11 publications

Sub-millisecond electron density profile measurement at the JET tokamak with the fast lithium beam emission spectroscopy system

Sub-millisecond electron density profile measurement at the JET tokamak with the fast lithium beam emission spectroscopy system

Beam modelling and hardware design of an imaging heavy ion beam probe for ASDEX Upgrade

Advanced neutral alkali beam diagnostics for applications in fusion research (invited)

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