High field side launch of RF waves: A new approach to reactor actuators

Wallace, G. M.; Baek, S. G.; Bonoli, P. T.; Faust, I.; LaBombard, B.; Lin, Y.; Mumgaard, R.; Parker, R.; Shiraiwa, S.; Vieira, R.; Whyte, D.G.; Wukitch, S.J.

doi:10.1063/1.4936482

Cited by 14 publications

(4 citation statements)

References 29 publications

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“…We find that moving the launch position from the low field side toward the high field side can lead to a larger increase of the central poloidal number m 0 as shown in figures 7(d)-( f ), namely, a larger increase of the parallel refractive index n , which is helpful for the wave penetration into the core plasma by avoiding the mode conversion. Although a similar conclusion has been derived from WKB simulation [5,52,53], it is veri fied by the particle simulation in toroidal geometry for the first time. Since we want to study here the poloidal spectrum evol ution effects on mode conversion, the simulations are carried out firstly with negligible absorptions (low electron temper ature).…”

Section: Linear Mode Conversion Between Slow and Fast Lh Waves In Torsupporting

confidence: 81%

“…Launching LH waves from different poloidal angle posi tions of the tokamak will lead to different propagations and absorptions. For example, recently launching LH waves from the high field side is proposed due to many significant advan tages such as the relaxed accessibility condition [52,53] and the strong poloidal wave number upshift for alpha particle channeling [54,55]. We now study the LH wave propagation from different launching positions in tokamaks.…”

Section: Linear Mode Conversion Between Slow and Fast Lh Waves In Tormentioning

confidence: 99%

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Electromagnetic particle simulation of the effect of toroidicity on linear mode conversion and absorption of lower hybrid waves

et al. 2016

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Effects of toroidicity on linear mode conversion and absorption of lower hybrid (LH) waves in fusion plasmas have been studied using electromagnetic particle simulation. The simulation confirms that the toroidicity induces an upshift of parallel refractive index when LH waves propagate from the tokamak edge toward the core, which affects the radial position for the mode conversion between slow and fast LH waves. Furthermore, moving LH antenna launch position from low field side toward high field side leads to a larger upshift of the parallel refractive index, which helps the slow LH wave penetration into the tokamak core. The broadening of the poloidal spectrum of the wavepacket due to wave diffraction is also verified in the simulation. Both the upshift and broadening effects of the parallel spectrum of the wavepacket modify the parallel phase velocity and thus the linear absorption of LH waves by electron Landau resonance.

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Section: Linear Mode Conversion Between Slow and Fast Lh Waves In Torsupporting

confidence: 81%

Section: Linear Mode Conversion Between Slow and Fast Lh Waves In Tormentioning

confidence: 99%

Electromagnetic particle simulation of the effect of toroidicity on linear mode conversion and absorption of lower hybrid waves

et al. 2016

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“…It should be noted that we only scanned a certain range of poloidal angle corresponding to the weak field side launch of helicon wave. For the high field side (HFS) launch of the waves, there are currently many studies on LHW [37][38][39]. The latest studies on the HFS launch of LHW indicate [32] that the wave is attenuated in the higher temperature region, which leads to improved CD efficiency.…”

Section: Helicon Wave Power Absorption and Current Drivementioning

confidence: 99%

Helicon wave heating and current drive in toroidal plasmas

Ding

Dong

et al. 2020

Plasma Phys. Control. Fusion

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Investigation of helicon wave heating and current drive (CD) in toroidal plasma has been carried out with the ray-tracing code GENRAY. The wave trajectories, profiles of power deposition and driven-currents are presented. It is shown that increasing the poloidal launch angle does not change the absorption rate of the wave, but moves the peak of the wave deposition toward the plasma core. Wave frequencies in the range of our interest (460 MHz ∼ 480 MHz) do not change the absorption of the wave. Under low parameter plasmas, we find that both the peak position and magnitude of the wave power deposition are dependent on the launched parallel refractive index n || . With increasing the refractive index, the driving efficiency first increases and then decreases. The parallel refractive index figure of merit for mid-plane launching in HL-2M configuration is 3.2. With high plasma parameters, both the position and magnitude of the driving current are weakly dependent on n || . The magnitude of the driven current is determined by both the absorption rate and the value of ξ e , which is related to n || . It is also demonstrated that driven current increases with increase of the core plasma temperature and decrease of the core plasma density. The plasma ohmic current seems do not significantly affect the helicon CD efficiency, but moves the driven current toward the plasma core region and narrows the width of the driven current profile. In addition, the preliminary calculations including scrape-off-layer (SOL) suggest that the power absorption rate loss in SOL is about 5%-20%. These results provide a reference and theoretical basis for the design and construction of HL-2M helicon wave system.

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“…In recent years, some reactor studies have identified strong advantages to the placement of rf wave launchers on the high-field side (HFS, inboard midplane region) of the torus over the usual location in the outboard midplane region [21]. For a moderate aspect ratio torus, significant advantages of HFS launch over LFS launch for slow lower hybrid waves are particularly clear from a wave physics point of view.…”

Section: High-field-side-launched Lhcdmentioning

confidence: 99%

Tests of advanced RF off-axis current drive techniques on DIII-D

et al. 2019

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The establishment of reactor-relevant radiofrequency heating and current drive techniques is a focus of work on DIII-D in the next five-year period. This paper gives an overview of the planned experimental work in the areas of (1) nearly vertically launched ECCD, (2) ‘helicon’ (whistlers or fast waves in the lower hybrid range of frequencies) current drive, and (3) high-field-side-launch (HFS) lower hybrid (slow wave) current drive. Each of these techniques addresses the need for efficient off-axis current drive for a steady-state tokamak reactor to supplement the bootstrap current and to provide current profile control, and each will be experimentally assessed at a coupled power level of ~1 MW on DIII-D in the next few years.

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High field side launch of RF waves: A new approach to reactor actuators

Cited by 14 publications

References 29 publications

Electromagnetic particle simulation of the effect of toroidicity on linear mode conversion and absorption of lower hybrid waves

Electromagnetic particle simulation of the effect of toroidicity on linear mode conversion and absorption of lower hybrid waves

Helicon wave heating and current drive in toroidal plasmas

Tests of advanced RF off-axis current drive techniques on DIII-D

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