Development and Application of 3.7GHz LHCD system on HL-2A and Development of RF Heating system on HL-2M

Lü, B.; Zeng, Hao; Liang, Jun; Wang, Chao; Xiao, Guoliang; He, Wang; Chen, Yali; Wang, Jieqiong; Feng, Kai; Song, Shaodong; Huang, M.; Rao, Jun; Song, X.M.; Mao, Rui; Cheng, J.; Zhang, Yipo; Yu, D.L.; Zhou, Yan; Shi, Z.B.; Hillairet, J.; Bertrand, Emmanuel; Delpech, L.; Giruzzi, G.; Hoang, T.; Magne, R.; Mazon, D.; Peysson, Y.; Zou, X. L.

doi:10.1051/epjconf/201715702001

Cited by 7 publications

(5 citation statements)

References 15 publications

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“…The boundaries of the spectral propagation domain at Z = Z p are shown in Figs. 2, 3 and 4 for plasma parameters corresponding to the discharge #35261 at time t = 0.8 s. For this simulation, the main lobe in the launched power spectrum calculated by the ALOHA coupling code for the Passive Active Multi-junction (PAM) is located at N k0 ' 2.95 [32,37]. As shown in Sec.3.3, the power spectrum exhibits multiple large satellite lobes.…”

Section: Kinematics Of the Lh Wavementioning

confidence: 97%

“…Consequently, current drive efficiency should be rather low, according to Fisch's current drive theory [9]. Like WEST tokamak, it is equipped with a Passive Active Multi-junction (PAM) operating at the same frequency f LH = 3.7 GHz with 4 horizontal rows of waveguides grouped in 4 modules per row symmetrically placed in the low field side around the equatorial mid-plane [37]. Full current drive has been achieved in the discharge #35261 by launching 840 kW of LH power [50].…”

Section: Hl-2a Tokamak Discharge #35261mentioning

confidence: 99%

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Lower Hybrid Current Drive in High Aspect Ratio Tokamaks

Peysson

Mazon²,

Artaud³

et al. 2020

J Fusion Energ

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A multi-machine study has been carried out to investigate the impact of a strongly bounded wave propagation domain on the Lower Hybrid current drive, a condition which occurs principally in high aspect ratio tokamaks. In this regime, the condition of kinetic resonance can be far above the upper boundary of the propagation domain, and may not be achieved by the usual toroidal upshift. Therefore no tail of fast electrons can be pulled out from the thermal bulk. Nevertheless, while tokamak plasmas are in principle almost transparent to the wave in this regime so-called "unbridgeable spectral gap", full current drive is well achieved for the two tokamaks considered in this study, TRIAM-1M [H. Zushi, et al., Nucl. Fusion 43 (2003) 1600] and WEST [C. Bourdelle, et al., Nucl. Fusion 55 (2015) 063017], both characterized by a very large aspect ratio R/a > 5.5. The case of the high aspect ratio tokamak HL-2A [Y. Liu et al. Nucl. Fusion 45 (2005) S239] for which the wave propagation domain has also an upper boundary, but close to the resonance condition, is considered by comparison. First principles modeling of the rf-driven current and the fast electron bremsstrahlung using the ALOHA/C3PO/LUKE/R5-X2 chain of codes shows unambiguously that the spectral gap must be already filled at the separatrix in order to reproduce quantitatively observations and some important parametric dependencies. This result is an important milestone in the physics understanding of the Lower Hybrid current drive, highlighting the existence of a powerful and likely universal alternative mechanism to bridge the spectral gap, that is not related to toroidal magnetic refraction. With an initially broad power spectrum, lobes with low parallel refractive indexes that carry most of the plasma current can be absorbed in almost single pass, restoring the full validity of the ray-tracing approximation for describing the propagation of the Lower Hybrid wave in cold plasmas.

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Section: Kinematics Of the Lh Wavementioning

confidence: 97%

Section: Hl-2a Tokamak Discharge #35261mentioning

confidence: 99%

Lower Hybrid Current Drive in High Aspect Ratio Tokamaks

Peysson

Mazon²,

Artaud³

et al. 2020

J Fusion Energ

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“…Besides, dedicated experiments on Tore Supra, which were carried out at low power and with a wide range of edge electron densities, show that the electromagnetic properties of the PAM are in good agreement with the predictions by linear coupling theory [12]. The coupling characteristics of PAM launcher in ELMy H-mode plasmas were first tested on HL-2A, but the pulse length was limited to <1 s [13].…”

Section: Introductionmentioning

confidence: 68%

First experimental results of the PAM LHCD launcher at 2.45 GHz on EAST

Li¹,

Liu²,

Wang³

et al. 2023

Nucl. Fusion

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This paper presents the first results of a passive active multijunction (PAM) launcher at 2.45 GHz during the lower hybrid current drive (LHCD) experiments on EAST. Good coupling performance with a power reflection coefficient (RC) ~ 3% has been achieved at the plasma-antenna distance up to ~ 11 cm in L-mode edge plasmas without local gas puffing near the PAM launcher. Reliable power coupling of this PAM during the edge perturbations induced by type I ELMs has been successfully demonstrated. Compared with the old full active multijunction (FAM) launcher, the new PAM can be placed ~ 2 cm further away from the plasma in normal operations, which is in good agreement with the previous prediction (Li et al. 2019 Fusion Eng. Des. 147 111250), by the linear wave-plasma coupling code ALOHA (Hillairet et al. 2010 Nucl. Fusion 50 125010). The flexibility of the power spectrum by changing the phase difference between adjacent modules was validated and ray-tracing / Fokker-Planck simulations can reproduce the experimental features. The achievable power handling is as high as 25 MW m-2, although with a shot pulse length of ~ 10 s. The first experiment successfully demonstrated the coupling performance of a PAM launcher at low density and this launcher construction provides helpful engineering experience for the 4.6 GHz PAM development in the near future on EAST.

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“…A detailed conceptual study of PAM launchers at 3.7 GHz and 5.0 GHz was carried out for JET [25] and ITER [26,27], although the LHCD system has been removed on both machines. The PAM characteristic of good coupling with the edge density very close or even lower than the cut-off value has been demonstrated on several devices, for instance, FTU with wave frequency at 8.0 GHz [28], Tore Supra [29] and HL-2 A [30] with 3.7 GHz, and EAST with 2.45 GHz [13]. It is well known that the wave frequency (f ) on a reactor could not be too high, because high frequency means high electron density required for coupling (n e_co ∝ f 2 ); and f could not be too low to avoid PDIs (as discussed above) and to reduce the parasitic power absorption by alpha particles (low frequency corresponds to small perpendicular refractive index) [31].…”

Section: Introductionmentioning

confidence: 89%

Design and analysis of a PAM launcher at 4.6 GHz for a new LHCD system on EAST

Li,

Liu,

Yang

et al. 2024

Nucl. Fusion

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To improve the current drive (CD) capability in long-pulse (up to ~ 1000 s) H-mode operation, it has been decided to develop a new lower hybrid current drive (LHCD) system at 4.6 GHz with an active cooling passive active multijunction (PAM) launcher on EAST. In this paper, both the RF and the physical properties of this PAM are studied numerically. The same nominal parallel refractive index (N|| = k||c/ω, where k|| is the parallel wavenumber, c the velocity of light, and ω the wave frequency) of 2.04 as the existing 4.6 GHz full active multijunction (FAM) is chosen. Ray-tracing calculations indicate that good accessibility could be achieved when the LH waves radiate with this nominal N|| in typical long-pulse H-mode plasmas. The coupling performance in terms of power reflection coefficient (RC), power spectrum, maximum electric field, power directivity (DP) and global CD capability is evaluated with the ALOHA code based on the linear coupling theory. Good coupling performance with averaged RC ≦ 1% and DP ~ 70% could be expected with the density (ne) in front of the PAM close to the cut-off value (ne_co). The simulated RC remains below 6.5% over a wide density range 0.5 ≦ ne/ne_co ≦ 10, which is similar to the plasma edge conditions produced by edge localized mode (ELM) activity. A detailed comparison with the existing 4.6 GHz FAM launcher is also performed.

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Development and Application of 3.7GHz LHCD system on HL-2A and Development of RF Heating system on HL-2M

Cited by 7 publications

References 15 publications

Lower Hybrid Current Drive in High Aspect Ratio Tokamaks

Lower Hybrid Current Drive in High Aspect Ratio Tokamaks

First experimental results of the PAM LHCD launcher at 2.45 GHz on EAST

Design and analysis of a PAM launcher at 4.6 GHz for a new LHCD system on EAST

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