Test result of 5 GHz, 500 kW CW prototype klystron for KSTAR LHCD system

Do, Heejin; Park, S.; Jeong, J.H.; Bae, Y.S.; Yang, H.L.; Delpech, L.; Magne, R.; Hoang, G. T.; Park, H.; Cho, M.H.; Namkung, W.

doi:10.1016/j.fusengdes.2011.02.054

Cited by 10 publications

(3 citation statements)

References 5 publications

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“…This system features a high power prototype klystron from Toshiba Electron Devices, operating at 5 GHz, the frequency required for ITER. The klystron has a triode gun and six cavities to amplify the RF signal, which is coupled to two standard WR187 waveguides through two BeO ceramic windows [26].…”

Section: Kstarmentioning

confidence: 99%

Advances in multi-megawatt lower hybrid technology in support of steady-state tokamak operation

et al. 2014

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It has been demonstrated that lower hybrid current drive (LHCD) systems play a crucial role for steady-state tokamak operation, owing to their high current drive (CD) efficiency and hence their capability to reduce flux consumption. This paper describes the extensive technology programmes developed for the Tore Supra (France) and the KSTAR (Korea) tokamaks in order to bring continuous wave (CW) LHCD systems into operation. The Tore Supra LHCD generator at 3.7 GHz is fully CW compatible, with RF power PRF = 9.2 MW available at the generator to feed two actively water-cooled launchers. On Tore Supra, the most recent and novel passive active multijunction (PAM) launcher has sustained 2.7 MW (corresponding to its design value of 25 MW m−2 at the launcher mouth) for a 78 s flat-top discharge, with low reflected power even at large plasma-launcher gaps. The fully active multijunction (FAM) launcher has reached 3.8 MW of coupled power (24 MW m−2 at the launcher mouth) with the new TH2103C klystrons. By combining both the PAM and FAM launchers, 950 MJ of energy, using 5.2 MW of LHCD and 1 MW of ICRH (ion cyclotron resonance heating), was injected for 160 s in 2011. The 3.7 GHz CW LHCD system will be a key element within the W (for tungsten) environment in steady-state Tokamak (WEST) project, where the aim is to test ITER technologies for high heat flux components in relevant heat flux density and particle fluence conditions. On KSTAR, a 2 MW LHCD system operating at 5 GHz is under development. Recently the 5 GHz prototype klystron has reached 500 kW/600 s on a matched load, and studies are ongoing to design a PAM launcher. In addition to the studies of technology, a combination of ray-tracing and Fokker–Planck calculations have been performed to evaluate the driven current and the power deposition due to LH waves, and to optimize the N∥ spectrum for the future launcher design. Furthermore, an LHCD system at 5 GHz is being considered for a future upgrade of the ITER Heating and Current Drive systems, with a power capability of 20 MW coupled to the plasma using a PAM launcher. An R&D programme is being conducted at CEA/IRFM to develop a BeO vacuum window which is a safety critical component of the transmission line. In addition, a mock-up of a TE10–TE30 mode converter at 5 GHz, designed for a rectangular transmission line, has been manufactured and successfully tested on Tore Supra at low RF power.

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Section: Kstarmentioning

confidence: 99%

Advances in multi-megawatt lower hybrid technology in support of steady-state tokamak operation

et al. 2014

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“…pulse duration of 800 s and 450 kW at the pulse duration 20 s using the two water dummy loads during the commissioning [33]. The highest temperature at collector top surface was saturated at 83…”

Section: Klystron Power Source Developmentmentioning

confidence: 99%

Advances in Lower Hybrid Current Drive for Tokamak Long Pulse Operation: Technology and Physics

Hoang¹,

Delpech²,

Bae

et al. 2012

Plasma and Fusion Research

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The paper gives a picture of the present status and understanding of technology and physics of Lower Hybrid Current Drive for long pulse operation in tokamaks, including the development of continuous wave (CW) high power klystrons, and its evolutions towards ITER. 3.7 GH / 700 kW CW klystrons produced in series by Thales Electron Devices are now in operation on Tore Supra. First series of eight klystrons delivered more than 4 MW to sustain non-inductive plasmas during 50 s. Moreover, a prototype of 500 kW CW klystron operating at 5 GHz developed for KSTAR by Toshiba Electron Tubes and Devices, and foreseen for ITER, is able to produce RF output powers of 300 kW / 800 s and 450 kW / 20 s on matched load. The situation on wave coupling and antennas is reported, with the latest Tore Supra results of the new CW Passive-Active Multi-junction (PAM) launcher: the antenna concept foreseen for ITER. First experiments with the PAM antenna in Tore Supra have provided extremely encouraging results in terms of power handling and coupling. Relevant ITER power density of ∼25 MW/m 2 (2.7 MW of power injected into the plasma) has been maintained over ∼80 s. In addition, LH power of 2.7 MW has been coupled at a plasma-antenna distance of 10 cm.

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“…Other klystrons with similar power are commercially available at 3.7 GHz and 2.45 GHz, however results from EAST comparing 2.45 and 4.6 GHz LHCD systems show higher efficiency for the higher frequency [23], particularly for high density operation. A prototype klystron developed by toshiba electron tubes and devices company Japan operating producing 450 kW at 5.0 GHz [24] would also be an attractive power source, but is not available commercially at this time. The highest frequency LHCD system in operation is the 8.0 GHz system on FTU [25], however this system makes use of gyrotron oscillators rather than klystron amplifiers.…”

Section: Introductionmentioning

confidence: 99%

Scoping study of lower hybrid current drive for CFETR

Wallace¹,

Ding²,

Li³

et al. 2021

Nucl. Fusion

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The paper assesses the applicability of lower hybrid current drive (LHCD) for two potential operating scenarios for the china fusion engineering test reactor (CFETR): the ‘hybrid’ scenario in which some of the plasma current is sustained by the ohmic transformer, and the fully non-inductive ‘steady state’ scenario. The π scope workflow engine was used to set up a large number of ray tracing/Fokker–Planck simulations (>104) with parametric scans in the antenna poloidal position and launched parallel refractive index (n ‖) for both the hybrid and steady state scenarios. Modeling predicts efficient off-axis current drive (1.3 MA for 20 MW launched power) with a peak near ρ of 0.6–0.65 for waves launched from the high field side (HFS). Waves launched from the low field side damp at larger radius (ρ > 0.73) with similar efficiency to HFS launch. Stability analysis of the CFETR scenarios favors current drive profiles peaked near the mid-radius, suggesting that HFS launch is preferable due to the current drive location. The effect of wave scattering from density blobs in the edge/scrape-off-layer region was assessed through rotation of the perpendicular wavenumber at the ray origin. Simulations show that this effect can be quite large both in efficiency and damping location, however by adjusting the launched n ‖ much of the unperturbed performance can be recovered.

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Test result of 5 GHz, 500 kW CW prototype klystron for KSTAR LHCD system

Cited by 10 publications

References 5 publications

Advances in multi-megawatt lower hybrid technology in support of steady-state tokamak operation

Advances in multi-megawatt lower hybrid technology in support of steady-state tokamak operation

Advances in Lower Hybrid Current Drive for Tokamak Long Pulse Operation: Technology and Physics

Scoping study of lower hybrid current drive for CFETR

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