Analysis of the ITER low field side reflectometer employing the Beam Tracing Method

Stegmeir, A.; Poli, E.; Strumberger, E.

doi:10.1016/j.fusengdes.2011.07.006

Cited by 5 publications

(10 citation statements)

References 30 publications

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“…2) have been developed and are available as part of the post-processing tools. These extensions of the code, already documented in [11], are briefly reviewed in Sec. 7.…”

Section: Andmentioning

confidence: 99%

“…(8,9) and solving only for Eqs. (7,11). This step, which turns TORBEAM into a raytracing code computing a single ray, makes also the preparation of second-derivatives finite-difference arrays unnecessary.…”

Section: Real-time Applicationsmentioning

confidence: 99%

“…Consequently, first and second-order derivatives of the temperature profile need to be calculated, which are otherwise absent since the propagation of the beam is computed in usual heating and current drive applications according to the cold-plasma dispersion relation. These corrections were added for a design study of the ITER low-field-side reflectometer [11]. A typical example of beam propagation and cutoff profiles is shown in Fig.…”

Section: Reflectometry Applicationsmentioning

confidence: 99%

“…In addition to the quantities at the turning point returned by the code in reflectometry applications, see Sec. 3, the information about the beam parameters provided by the pWKB method allows one to determine also the coupling between the beam and the receiver antenna, which can be useful in assessing the measured signal and guide the design of future reflectometers, as described in [11]. The coupling efficiency T a is given [56,57] by the squared modulus of the integral (taken on the antenna plane) of the product of the beam field, given in terms of Eqs.…”

Section: Reflectometry Applicationsmentioning

confidence: 99%

“…The paraxial Wentzel-Kramers-Brillouin (pWKB) method for the propagation of highfrequency waves in plasmas, developed by Pereverzev [1,2], has been implemented numerically in the beam-tracing code TORBEAM [3] and since then used in a variety of studies for present [4,5,6] and future [7,8,9] fusion devices, for both heating and current drive applications employing waves in the electron cyclotron (EC) frequency range and for the analysis and interpretation of short-wavelength diagnostic techniques like reflectometry [10,11,12,13]. Applications of the pWKB method to lower-hybrid wave propagation have also been reported [14,15].…”

Section: Introductionmentioning

confidence: 99%

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TORBEAM 2.0, a paraxial beam tracing code for electron-cyclotron beams in fusion plasmas for extended physics applications

Poli

Bock

Lochbrunner

et al. 2018

Computer Physics Communications

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The paraxial WKB code TORBEAM [E. Poli et al., Comp. Phys. Comm. 136 (2001), 90] is widely used for the description of electron-cyclotron waves in fusion plasmas, retaining diffraction effects through the solution of a set of ordinary differential equations. With respect to its original form, the code has undergone significant transformations and extensions, in terms of both the physical model and the spectrum of applications. The code has been rewritten in Fortran 90 and transformed into a library, which can be called from within different (not necessarily Fortran-based) workflows. The models for both absorption and current drive have been extended, including e.g. fully-relativistic calculation of the absorption coefficient, momentum conservation in electron-electron collisions and the contribution of more than one harmonic to current drive. The code can be run also for reflectometry applications, with relativistic corrections for the electron mass. Formulas that provide the coupling between the reflected beam and the receiver have been developed. Accelerated versions of the code are available, with the reduced physics goal of inferring the location of maximum absorption (including or not the total driven current) for a given setting of the launcher mirrors. Optionally, plasma volumes within given flux surfaces and corresponding values of minimum and maximum magnetic field can be provided externally to speed up the calculation of full driven-current profiles. These can be employed in real-time control algorithms or for fast data analysis.

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“…2) have been developed and are available as part of the post-processing tools. These extensions of the code, already documented in [11], are briefly reviewed in Sec. 7.…”

Section: Andmentioning

confidence: 99%

Section: Real-time Applicationsmentioning

confidence: 99%

Section: Reflectometry Applicationsmentioning

confidence: 99%

Section: Reflectometry Applicationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

TORBEAM 2.0, a paraxial beam tracing code for electron-cyclotron beams in fusion plasmas for extended physics applications

Poli

Bock

Lochbrunner

et al. 2018

Computer Physics Communications

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Real-time beam tracing for control of the deposition location of electron cyclotron waves

Reich

Bilato

Mszanowski

et al. 2015

Fusion Engineering and Design

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Plasma control techniques that use electron cyclotron (EC) resonance heating and current drive such as control of neoclassical tearing modes require accurate control of the deposition location of EC beams. ASDEX Upgrade has successfully implemented a real-time version of the beam-tracing code TORBEAM into its real-time diagnostic system to act as a globally available module that calculates current deposition location and its sensitivity from other real-time diagnostic measurements for all its moveable EC wave launchers. Based on a highly (100 x) accelerated version of TORBEAM, the software implementation as a diagnostic process uses parallelization and achieves cycle times of 15-20 ms for determining the radial deposition location of 12 beams in the plasma. This cycle time includes data input-output overhead arising from the use of available realtime signals. The system is by design portable to other machines such as ITER.

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Beam model of Doppler backscattering

Hall-Chen

Parra

Hillesheim

2022

Plasma Phys. Control. Fusion

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We use beam tracing --- implemented with a newly-written code, Scotty --- and the reciprocity theorem to derive a model for the linear backscattered power of the Doppler Backscattering (DBS) diagnostic. Our model works for both the O-mode and X-mode in tokamak geometry (and certain regimes of stellarators). We present the analytical derivation of our model and its implications on the DBS signal localisation and the wavenumber resolution. To determine these two quantities, we find that it is the curvature of the field lines and the magnetic shear that are important, rather than the curvature of the cut-off surface. We also provide an explicit formula for the hitherto poorly-understood quantitative effect of the mismatch angle. Consequently, one can use this model to correct for the attenuation due to mismatch, avoiding the need for empirical optimisation. This is especially important in spherical tokamaks, since the magnetic pitch angle is large and varies both spatially and temporally.

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Analysis of the ITER low field side reflectometer employing the Beam Tracing Method

Cited by 5 publications

References 30 publications

TORBEAM 2.0, a paraxial beam tracing code for electron-cyclotron beams in fusion plasmas for extended physics applications

TORBEAM 2.0, a paraxial beam tracing code for electron-cyclotron beams in fusion plasmas for extended physics applications

Real-time beam tracing for control of the deposition location of electron cyclotron waves

Beam model of Doppler backscattering

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