Plasma irradiation experiment on the metal pebble flow in the TPDsheet-U

Ohgo, Takeru; Goto, Takuya; Takimoto, Toshikio; Tonegawa, Akira; Miyazawa, J.

doi:10.1016/j.fusengdes.2021.112236

Cited by 3 publications

(4 citation statements)

References 19 publications

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“…It should be noted that this <GHD> is estimated for the case without the pebble divertor. In this study, 70 % of the divertor heat load is assumed to be absorbed by the pebble divertor and the rest of 30 % goes to the helical divertor, as in the former studies [8,9]. With the pebble divertor, <GHD> can be reduced to 6.3 ´ 0.3 ~ 1.9 MW/m 2 .…”

Section: Device Parameters Of the Ffhr-b3mentioning

confidence: 98%

“…The MHD force due to this electric current and the high magnetic field inside the reactor can cause a large deformation of the tin jet [7]. To avoid this, liquid tin shower has been replaced by solid tin pebble shower in the next design named the REVOLVER-D2 [8,9]. Tin pebbles are dropped to the inboard side ergodic layer and play a role of limiter.…”

Section: Introductionmentioning

confidence: 99%

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Coordinated design of the cartridge-type blanket and the ceramic pebble divertor for the helical reactor FFHR-b3

Miyazawa¹,

Goto²,

Hamaji³

et al. 2021

Nucl. Fusion

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The cartridge-type blanket for the helical reactor has been updated and named the CARDISTRY-B3. Together with this, the ceramic pebble ergodic limiter/divertor system named the REVOLVER-D3 has been adopted in the design. There was a difficulty in fabricating the blanket cartridges due to the first wall shape with three-dimensional surface. This difficulty has been removed by introducing the slit first wall, where the first wall surface is formed by alternately stacking solid metal plates and porous plates made of metal or ceramic. The liquid metal flowing inside the blanket cartridge oozes out through the porous plates and forms the surface flow covering the first wall. Solid target plates for the helical divertor has been omitted, because the divertor region is already covered and protected by the liquid metal surface flow. The liquid metal freely falls inside the blanket cartridges by the gravity force and then exhausted to the pool set on the lower port. The ceramic pebbles, which are dropped to the inboard-side ergodic layer to form the flowing limiter divertor, also flow into the liquid metal pool. The pebbles and liquid metal are individually elevated again by screw conveyers. Since the free surface of the liquid metal is exposed to the plasma, the vapor pressure of the working liquid metal should be low enough. Ternary or quadruple alloys, which include Li, Sn, Pb (or Bi), and Er, have been selected as the candidates of the functional liquid metal for the CARDISTRY-B3 that satisfies the requirements of low vapor pressure, low density, low melting point, and high tritium breeding ratio. In this study, the coordinated design of CARDISTRY-B3 and REVOLVER-D3 for the FFHR-b3 is presented. The FFHR-b3 is one of the design options that aims at demonstration of 100 MW net electricity with two times larger devise size than LHD.

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Section: Device Parameters Of the Ffhr-b3mentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Coordinated design of the cartridge-type blanket and the ceramic pebble divertor for the helical reactor FFHR-b3

Miyazawa¹,

Goto²,

Hamaji³

et al. 2021

Nucl. Fusion

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“…The REVOLVER-D3 is a newly proposed limiter/divertor system using falling massive ceramic pebbles as the plasma facing material (PFM). This concept is based on the former concepts of the REVOLVER-D [12] and the REVOLVER-D2 [13,14], which adopt the melted tin shower jets and the solid tin pebbles, respectively, for the PFM. The multi-layered ceramic pebble divertor concept was intensively studied in Osaka Univ.…”

Section: Main Features Of the Ffhr-b2mentioning

confidence: 99%

Novel features of the helical volumetric neutron source FFHR-b2

Miyazawa¹,

Goto²,

Hamaji³

et al. 2021

Nucl. Fusion

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The compact helical fusion reactor FFHR-b2 is a multipurpose HElical Volumetric Neutron Source (HEVNS) available as the component test facility to test the divertor and blanket systems. In the latest design, three new technologies of the HTS (High-Temperature Superconducting) conductor, the ceramic pebble divertor, and the cartridge-type blanket are adopted. Tin-based functional liquid metals (FLMs) including lithium are considered as the working fluid for the blanket. The FLMs have multi functions of low vapor pressure, low density, low melting point, low corrosiveness, high tritium breeding ratio, and so on. The target construction cost of the FFHR-b2 has been set to 200 billion JPY. The main target of FFHR-b2 is to demonstrate the fusion gain larger than one. To achieve this in a relatively small device, the tangential Neutral Beam Injection (NBI) heating with a moderate energy of 80 keV is adopted for the FFHR-b2. The beam-plasma fusion with 5 MW of NBI heating can produce a fusion power of 5 MW that is larger than the absorbed power of 3 MW.

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“…An unconventional idea to address the issue caused * Author to whom any correspondence should be addressed. by high heat fluxes is the concept of liquid metal divertors [7][8][9][10][11][12]. The use of liquid metals as the divertor materials can improve in the tolerance to high thermal and neutron loads.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of droplet ejection from liquid gallium interacting with inductively coupled hydrogen plasma

Hamana,

Shirai,

Sasaki

2023

J. Phys. D: Appl. Phys.

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In this study, we observed droplet ejection from liquid gallium interacting with an inductively coupled hydrogen plasma. We observed the formation of a bubble in the liquid gallium, and the droplet ejection was synchronized with the burst of the bubble. We examined droplet ejection frequency by varying the ion flux [(0.2 – 7.1) × 1014 cm-2s-1], the ion energy (15 – 215 eV), and the liquid gallium temperature (370 K – 500 K). As a result, we found that the droplet ejection frequency increased with the ion flux and the liquid gallium temperature, whereas it decreased with the ion energy. We observed that the inside of the bubble in the liquid gallium was occupied by hydrogen. Furthermore, the amount of hydrogen dissolved in the liquid gallium was dependent on the discharge conditions. On the basis of the experimental results, we have proposed a mechanism for bubble formation and droplet ejection. The key in the mechanism is the supersaturated dissolution of hydrogen due to the ion irradiation.

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Plasma irradiation experiment on the metal pebble flow in the TPDsheet-U

Cited by 3 publications

References 19 publications

Coordinated design of the cartridge-type blanket and the ceramic pebble divertor for the helical reactor FFHR-b3

Coordinated design of the cartridge-type blanket and the ceramic pebble divertor for the helical reactor FFHR-b3

Novel features of the helical volumetric neutron source FFHR-b2

Mechanism of droplet ejection from liquid gallium interacting with inductively coupled hydrogen plasma

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