Lithium beam diagnostic system on the COMPASS tokamak

Anda, G.; Bencze, A.; Berta, M.; Dunai, D.; Hacek, P.; Krbec, J.; Réfy, D.; Krizsanóczi, T.; Bató, S.; Ilkei, T.; Kiss, I.; Veres, G. I.; Zoletnik, S.

doi:10.1016/j.fusengdes.2016.04.022

Cited by 20 publications

(13 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…HRTS uses two 1.5 J Nd:YAG lasers with a repetition rate of 30 Hz each. In addition, the Lithium beam emission spectroscopy (Li-BES) system [4] provides profiles of edge plasma density with temporal resolution up to 4 µs.…”

Section: The Compass Tokamakmentioning

confidence: 99%

Contribution to the multi-machine pedestal scaling from the COMPASS tokamak

et al. 2017

Self Cite

View full text Add to dashboard Cite

The properties of the edge transport barrier are essential for the performance of ITER and next-step devices. Due to the stiffness of radial density and temperature profiles, the height of the edge pedestal has a direct impact on the fusion performance of the tokamak. At the same time, the plasma stability is determined by the pressure gradient, which depends on the pedestal width. Despite its importance, analytical models capable of predicting pedestal parameters for ITER were not available until a recent success of the EPED model. Validation of EPED and empirical scaling laws requires measurements of pedestal parameters on existing machines in ITER relevant regimes. We report on such measurements in the COMPASS tokamak.

show abstract

Section: The Compass Tokamakmentioning

confidence: 99%

Contribution to the multi-machine pedestal scaling from the COMPASS tokamak

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…The most common utilization of the Li-BES technique is to measure plasma edge density profiles, which feature has been demonstrated on numerous fusion devices: ASDEX Upgrade, 2 COMPASS, 3 DIII-D, 4 EAST, 5 JET, 6 KSTAR, 7 LHD, 8 TEXTOR, 9 and W7-AS. 10 Further capabilities such as measurement of the density fluctuations, 2,[11][12][13] poloidal flow velocity, 14 ion temperature, 15 impurity ion density profile, 16 and edge current profile 17 have been demonstrated.…”

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

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…The ion beam required for the measurement is produced by a simplified version of the Li-beam injector described in Ref. 24 . The approximately 1 mA ion beam is extracted with 3 kV and accelerated with 27 kV from a thermionic emitter with a 2 stage ion optic.…”

Section: A Lithium Beam Injectormentioning

confidence: 99%

Micro-Faraday cup matrix detector for ion beam measurements in fusion plasmas

Réfy

Zoletnik

Dunai

et al. 2019

Review of Scientific Instruments

Self Cite

View full text Add to dashboard Cite

Atomic Beam Probe (ABP) is an extension of the routinely used Beam Emission Spectroscopy (BES) diagnostic for plasma edge current fluctuation measurement at magnetically confined plasmas. Beam atoms ionized by the plasma are directed to a curved trajectory by the magnetic field and may be detected close to the wall of the device. The arrival location and current distribution of the ions carry information about the plasma current distribution, the density profile and the electric potential in the plasma edge. This paper describes a micro-Faraday cup matrix detector for the measurement of the few microampere ion current distribution close to the plasma edge. The device implements a shallow Faraday cup matrix, produced by printed-circuit board technology. Secondary electrons induced by the plasma radiation and the ion bombardment are basically confined into the cups by the tokamak magnetic field. Additionally, a double mask is installed in the front face to limit ion influx into the cups and supplement secondary electron suppression. The setup was tested in detail using a Lithium ion beam in the laboratory. Switching time, cross talk and fluctuation sensitivity test results in the lab setup are presented, along with the detector setup to be installed at the COMPASS tokamak.

show abstract

Lithium beam diagnostic system on the COMPASS tokamak

Cited by 20 publications

References 12 publications

Contribution to the multi-machine pedestal scaling from the COMPASS tokamak

Contribution to the multi-machine pedestal scaling from the COMPASS tokamak

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

Micro-Faraday cup matrix detector for ion beam measurements in fusion plasmas

Contact Info

Product

Resources

About