Development of gyrotrons for fusion with power exceeding 1 MW over a wide frequency range

Kariya, T.; Imai, T.; Minami, R.; Numakura, T.; Eguchi, Takanori; Kato, Tatsuro; Endo, Yukari; Ichimura, M.; Shimozuma, Τ.; Kubo, S.; Takahashi, H.; Yoshimura, Y.; Igami, H.; Ito, Satoshi; Mutoh, T.; Sakamoto, K.; Idei, H.; Zushi, H.; Nagasaki, K.; Sano, F.; Ono, M.; Mitsunaka, Y.

doi:10.1088/0029-5515/55/9/093009

Cited by 16 publications

(11 citation statements)

References 33 publications

(33 reference statements)

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“…The first tube of 28 GHz gyrotron with 1 MW and a few seconds pulse duration has been already fabricated and tested [9] as an ECH source for GAMMA 10 and other low B field devices. The obtained maximum output of this source is 1.38 MW.…”

Section: Resultsmentioning

confidence: 99%

Development of new mirror antenna for generation of high intermittent heat flux in GAMMA 10 tandem mirror

Minami¹,

Imai²,

Kariya³

et al. 2016

AIP Conference Proceedings

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Abstract. Electron cyclotron heating (ECH) power modulation experiments in GAMMA 10 tandem mirror have been carried out in order to generate and control the high heat flux and to make the ELM (edge localized mode) like intermittent heat load pattern for divertor simulation studies. The maximum energy density obtained by the use of present mirror antenna systems is about 0.08 MJ/m 2 and is still far lower than that of ITER ELM. To achieve the generation of higher heat flux, the development of a new mirror antenna has carried out in order to concentrate the heating power on the axis. The calculated e-folding radius of power density has been improved from 63 mm for the present mirror to 40 mm for the new mirror antenna.

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Section: Resultsmentioning

confidence: 99%

Development of new mirror antenna for generation of high intermittent heat flux in GAMMA 10 tandem mirror

Minami¹,

Imai²,

Kariya³

et al. 2016

AIP Conference Proceedings

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“…A 28 GHz gyrotron with a TE 8,3 cavity and a triode magnetron injection gun was developed at the University of Tsukuba [19]. A 1 MW maximum output power was obtained, and a high 40% oscillating efficiency was also demonstrated at 0.8 MW output without collector potential depression (CPD).…”

Section: Experimental Apparatusesmentioning

confidence: 99%

Electron heating of over-dense plasma with dual-frequency electron cyclotron waves in fully non-inductive plasma ramp-up on the QUEST spherical tokamak

et al. 2019

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A 28 GHz system with a high-power gyrotron tube has been used for the QUEST spherical tokamak to form an over-dense plasma for electron Bernstein wave (EBW) heating and current drive with an 8.2 GHz-wave. Non-inductive high-density plasma ramp-up experiments with dual-frequency (dual-f ) electron cyclotron (EC) (8.2 GHz and 28 GHz) waves were conducted. A spontaneous density jump (SDJ) to an over-dense state was first observed as a bifurcation phenomenon in the dual-f wave experiment. The over-dense plasma on the 8.2 GHz wave was non-inductively ramped up to 25 kA, and was maintained for 0.4 s under stable plasma equilibrium after two such jumps in one shot. Heating to mildly energetic electrons and bulk electrons was observed even in the over-dense region. The electrostatic EBW heating effect on the mildly energetic electrons in the over-dense region is assessed following a dispersion analysis of the 8.2 GHz wave. The bulk electron heating effect observed is explained as heat exchange from mildly energetic electrons heated by the electrostatic EBW. Remarkably, a high hard-x-ray-radiation temperature of ∼500 keV was also observed in tangential viewing for current-carrying electrons in the over-dense core region. Synergetic heating from the overlap of different 28 GHz EC harmonic resonances as well as higher harmonic heating is discussed for maintaining the highly energetic electrons in the over-dense core region. In addition, the SDJ process and mechanism are considered based on the discussion of the electron heating effects with the 8.2 GHz wave.

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“…The length of each transmission line is ~100 m. The fundamental (second harmonic) resonance magnetic field of frequency 77 (154) GHz is 2.75 T. The 77 and 154 GHz gyrotrons have been newly developed by collaboration with the University of Tsukuba and installed on the LHD ECH system in recent years. For a precise description of the technical and operational subjects of these gyrotrons, including a photo of one of them, see [19][20][21]. Each of the 77 and 154 GHz gyrotrons generates more than 1.0 MW port-through power at pulse operation of up to a few seconds.…”

Section: Ech System and Its Recent Upgradementioning

confidence: 99%

Progress of long pulse discharges by ECH in LHD

et al. 2016

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Using ion cyclotron heating and electron cyclotron heating (ECH), or solo ECH, trials of steady state plasma sustainment have been conducted in the superconducting helical/stellarator, large helical device (LHD) (Ida K et al 2015 Nucl. Fusion 55 104018). In recent years, the ECH system has been upgraded by applying newly developed 77 and 154 GHz gyrotrons. A new gas fueling system applied to the steady state operations in the LHD realized precise feedback control of the line average electron density even when the wall condition varied during long pulse discharges. Owing to these improvements in the ECH and the gas fueling systems, a stable 39 min discharge with a line average electron density n e_ave of 1.1 × 1019 m−3, a central electron temperature T e0 of over 2.5 keV, and a central ion temperature T i0 of 1.0 keV was successfully performed with ~350 kW EC-waves. The parameters are much improved from the previous 65 min discharge with n e_ave of 0.15 × 1019 m−3 and T e0 of 1.7 keV, and the 30 min discharge with n e_ave of 0.7 × 1019 m−3 and T e0 of 1.7 keV.

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Development of gyrotrons for fusion with power exceeding 1 MW over a wide frequency range

Cited by 16 publications

References 33 publications

Development of new mirror antenna for generation of high intermittent heat flux in GAMMA 10 tandem mirror

Development of new mirror antenna for generation of high intermittent heat flux in GAMMA 10 tandem mirror

Electron heating of over-dense plasma with dual-frequency electron cyclotron waves in fully non-inductive plasma ramp-up on the QUEST spherical tokamak

Progress of long pulse discharges by ECH in LHD

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