ALOHA: an Advanced LOwer Hybrid Antenna coupling code

Hillairet, J.; Voyer, Damien; Ekedahl, A.; Goniche, M.; Kazda, Michal; Meneghini, O.; Milanesio, Daniele; Preynas, M.

doi:10.1088/0029-5515/50/12/125010

Cited by 83 publications

(89 citation statements)

References 37 publications

(65 reference statements)

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“…1-6%) range for the 2.45GHz (resp.4.6GHz) antenna. This range is consistent with the RF modelling, provided by the ALOHA code [10], indicating an equivalent range of electron density in front of the launcher of 2-10 (resp. 1.3-5) time the cut-off density at 2.45GHz (resp.4.6GHz).…”

Section: The Experimental Databasesupporting

confidence: 88%

Influence of Li conditioning on Lower Hybrid Current Drive efficiency in H-mode and L- mode plasmas on EAST

Goniche

Peysson

et al. 2017

EPJ Web Conf.

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Abstract. The lower hybrid current drive efficiency on the EAST tokamak is estimated on a large database of low loop voltage discharges (V L <120mV) covering the 2016 campaign starting with lithium-free plasma facing components and ending with strong cumulated deposition of lithium. The efficiency is found to vary in a wide range from 0.6 to 1.2×10 19 A.W -1 .m -2 . No deleterious effect of the density on the efficiency is found between 2.3 and 3.2×10 19 m -3 . The high efficiency occurs after strong lithium evaporation. The low effective charge Z eff and the higher temperature of these discharges, can account for the high efficiency according to the expected scaling with Z eff and . Modelling with a ray-tracing code coupled to a Fokker-Planck solver supports this result, assuming that the fast electron transport is reduced in the zero loop voltage discharge with high efficiency.

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Section: The Experimental Databasesupporting

confidence: 88%

Influence of Li conditioning on Lower Hybrid Current Drive efficiency in H-mode and L- mode plasmas on EAST

Goniche

Peysson

et al. 2017

EPJ Web Conf.

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“…The plasma S-matrices used here are generated by the linear coupling code ALOHA [12]. Figure 4 shows the average matched reflection coefficient as a function of iteration number for a set of representative plasma conditions and phasings.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…The magnitude of matrix elements decreases farther away from the diagonal since radiating elements spaced farther apart have weaker cross-coupling. The magnitude and phase of S p for the fundamental mode as calculated by the ALOHA code [12] for a plasma with n 0 = 2.7 × 10 17 m −3 and ∇n = 4.7 × 10 20 m −4 are plotted in Figure 2. The pitch-angle of the magnetic field is not included in this calculation of S p .…”

Section: System Descriptionmentioning

confidence: 99%

Analysis of double stub tuner control stability in a phased array antenna with strong cross-coupling

Wallace

Hillairet

Koert

et al. 2014

Fusion Engineering and Design

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Active stub tuning with a fast ferrite tuner (FFT) has greatly increased the effectiveness of fusion ion cyclotron range of frequency (ICRF) systems (50-100 MHz) by allowing for the antenna system to respond dynamically to changes in the plasma load impedance such as during the L-H transition or edge localized modes (ELMs). A high power waveguide double-stub tuner is under development for use with the Alcator C-Mod lower hybrid current drive (LHCD) system at 4.6 GHz. The amplitude and relative phase shift between adjacent columns of an LHCD antenna are critical for control of the launched n || spectrum. Adding a double-stub tuning network will perturb the phase and amplitude of the forward wave particularly if the unmatched reflection coefficient is high. This effect can be compensated by adjusting the phase of the low power microwave drive for each klystron amplifier. Crosscoupling of the reflected power between columns of the launcher must also be considered. The problem is simulated by cascading a scattering matrix for the plasma provided by a linear coupling model with the measured launcher scattering matrix and that of the FFTs. The solution is advanced in an iterative manner similar to the time-dependent behavior of the real system. System performance is presented under a range of edge density conditions from under-dense to over-dense and a range of launched n || . Simulations predict power reflection coefficients (Γ 2 ) of less than 1% with no contamination of the n || spectrum. Instability of the FFT tuning network can be problematic for certain plasma conditions and relative phasings, but reducing the control gain of the FFT network stabilizes the system.

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“…The ALOHA coupling code [11] was used for defining the design parameters for the PAM launcher. The peak parallel refractive index was chosen to n //0 = 2.75, in order to allow accessibility of the LH wave in HL-2A plasmas.…”

Section: Fig 2 Photo Of the Pam Launcher In Hl-2amentioning

confidence: 99%

“…There are eight transmission lines, about 40 m length each. Corrugated circular waveguides (Ø = 63.5 mm ) are applied in the transmission lines to keep the wave HE 11 propagation mode. The transmission lines are pumped to 10 -3 Pa level to avoid arcing.…”

Section: Ecrh Systemmentioning

confidence: 99%

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

et al. 2017

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Abstract. The first Lower Hybrid (LH) experiments were carried out with a Passive-Active Multijunction (PAM) launcher in H-mode plasmas. The experiments were performed on the HL-2A tokamak with the new 3.7 GHz LHCD system, installed and tested by SWIP in collaboration with CEA/IRFM. The ELMs and local gas impact on LH power coupling was studied in the experiments. The coupled LH power in HL-2A was 200-500kW at large gap at the first experiments and reaches 900 kW now in H-mode, while it reaches 1MW in L-mode. The LH experiments on HL-2A show that the PAM launcher is a viable concept for high performance scenarios. The LH power can be coupled at large plasma-launcher gap, and assist in triggering and sustaining H-modes. Finally, an overview of the RF heating systems for the tokamak HL-2M is given. HL-2M will dispose of a 4 MW LH system and a 8 MW ECRH system, both of which are currently under installation at SWIP.

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ALOHA: an Advanced LOwer Hybrid Antenna coupling code

Cited by 83 publications

References 37 publications

Influence of Li conditioning on Lower Hybrid Current Drive efficiency in H-mode and L- mode plasmas on EAST

Influence of Li conditioning on Lower Hybrid Current Drive efficiency in H-mode and L- mode plasmas on EAST

Analysis of double stub tuner control stability in a phased array antenna with strong cross-coupling

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

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