EP0069341A1 - Cible à métal liquide pour une source de neutrons de spallation - Google Patents

Cible à métal liquide pour une source de neutrons de spallation Download PDF

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Publication number
EP0069341A1
EP0069341A1 EP82105848A EP82105848A EP0069341A1 EP 0069341 A1 EP0069341 A1 EP 0069341A1 EP 82105848 A EP82105848 A EP 82105848A EP 82105848 A EP82105848 A EP 82105848A EP 0069341 A1 EP0069341 A1 EP 0069341A1
Authority
EP
European Patent Office
Prior art keywords
channel
proton beam
inlet opening
liquid
target according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP82105848A
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German (de)
English (en)
Inventor
Josef Dr. Fassbender
Gerhard Dr. Meister
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Forschungszentrum Juelich GmbH
Original Assignee
Forschungszentrum Juelich GmbH
Kernforschungsanlage Juelich GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Forschungszentrum Juelich GmbH, Kernforschungsanlage Juelich GmbH filed Critical Forschungszentrum Juelich GmbH
Publication of EP0069341A1 publication Critical patent/EP0069341A1/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H6/00—Targets for producing nuclear reactions

Definitions

  • the invention relates to a target for a spallation neutron source, which is formed using liquid metal, which rotates in a channel with a circulation pump arranged therein and a heat exchanger, a high-energy proton beam intended for the release of high-energy neutrons being provided by an uncovered channel in the channel Entry opening strikes a free surface of the liquid metal, and the channel being connected to a heating device for heating the flowing metal to an operating temperature above its melting temperature before the neutron source is started up.
  • Spallation neutron sources are devices in which a proton beam of high energy (order of magnitude: 1 Gev) is enclosed in a suitable substance to generate neutrons.
  • the proton beam is generated by an accelerator, the acceleration section of which is under high vacuum.
  • proton energies and proton currents are required at which generate powers of the order of a few MW within a volume of a few 100 cm 3 of the target material.
  • Targets for spallation neutron sources are known in various embodiments. They can be designed as solid targets, evaporation targets or liquid metal targets. As a result of the high proton energy required to generate spallation neutrons, one of the problems is that there is sufficient heat dissipation from the area of interaction between the proton beam and the target at the point where the proton beam hits the target guarantee. With solid targets, the heat is dissipated by heat conduction at temperatures below the melting point of the target material. As a result, the amount of heat that can be dissipated is limited.
  • the known prior art includes an embodiment in which a liquid metal jet flows through a vertical tube from top to bottom. The proton beam is shot vertically into the liquid column from above.
  • Targets of this type are e.g. in the designations No. 1 589 431 and 1 289 923.
  • the proton accelerator must either be arranged vertically or, if the proton accelerator beam is arranged horizontally, it must be deflected by 90 °. Because of the large overall length of the accelerator in one case and because of the difficulty in deflecting high-energy beams through large angles in the other case, considerable structural problems arise.
  • the invention is therefore based on the object of a target essentially formed by a liquid metal stream (in a flow channel) for a spallation neutron source in which the proton beam strikes the target horizontally or almost horizontally (ie inclined up to about 45 ") without deflection, without it being necessary to provide a disk covering the entry opening for the proton beam.
  • the free surface of the liquid metal stream which the proton beam strikes and which is to run essentially perpendicular to the proton beam, must therefore run essentially vertically or have a considerable vertical component.
  • the thickness of the liquid metal stream in the direction of the proton beam should be sufficient so that the proton energy is completely or substantially absorbed within the liquid metal.
  • the object on which the invention is based is achieved in the case of a target for a spallation neutron source of the type mentioned at the outset in accordance with the invention in that the plane of the proton beam inlet opening is arranged vertically or almost vertically and the channel in the region of the inlet opening has a shape which at least deflects of part of the liquid metal flow, and that the power of the pump is sufficient to bring about such a flow rate that liquid metal is prevented from escaping from the inlet opening.
  • a vertical component of the liquid level in the area of the inlet opening is thus forced through the use of hydrodynamic forces, whereby at the same time the fact is used that the liquid metal flow in the area of interaction with the proton beam anyway must have such a speed that the temperature increase due to energy absorption remains below values at which the vapor pressure of the liquid comes close to the Iloch vacuum pressure values.
  • the invention also makes use of the knowledge that, because of the external vacuum in the area of the proton beam inlet opening, there is no friction between the liquid flow and the surrounding gas. It is therefore not possible for vortices to form on the free liquid surface, which could impair the formation of a constant free surface of the metallic liquid in the area of impact of the proton beam.
  • a vertical or almost vertical free liquid metal surface is also created behind the plane formed by the entrance plane for the proton beam.
  • this surface is an isobaric surface on which the external pressure prevails everywhere. Under the given conditions, this external pressure is equal to the vacuum pressure of the proton accelerator.
  • the forces acting in steady-state operation maintain the difference between the external pressure and the pressure within the liquid metal.
  • the almost vertical free surface of the liquid metal flow that forms in the area of the entry opening for the proton beam enables the inclusion of a horizontal or almost horizontal proton beam without the need for a disk to cover the entry opening during stationary operation to be provided for the proton beam.
  • an expedient embodiment of the target according to the invention is that the channel is connected to a reservoir with an adjustable liquid level.
  • This shutter is opened as soon as the intended throughput is reached and the proton accelerator is switched on.
  • An undesirable refinement of the target according to the invention consists of liquid metal emerging from the inlet opening for the proton beam in an undesirable manner, that a collecting device connected to the circuit for the metallic liquid or the optionally provided storage container, for example, is approximately below the inlet opening for the proton beam the entrance opening for the proton beam emerging liquid metal is provided.
  • This collecting device is expediently designed such that it is connected to a heater by means of which the metal is retained in the liquid state and is conveyed back into the circuit or the reservoir via a pump arranged in a line connected to the circuit or the reservoir.
  • a very advantageous embodiment of the target according to the invention consists in that a cross-sectional narrowing of the channel is provided, which causes the flow to constrict perpendicular to the direction of flow.
  • the cross-sectional constriction is arranged upstream above the edge of the inlet opening that runs perpendicular to the direction of flow and extends at least over the width of the inlet opening.
  • the narrowing of the flow channel results in a local increase in the flow velocity and consequently a decrease in the local pressure within the liquid.
  • the cross section of the channel is approximately perpendicular to the flow direction extending edge of the inlet opening for the proton beam, from which the liquid metal flows out of the inlet opening, extended towards the upstream part of the channel.
  • the consequence of the expansion of the flow cross-section provided for the proton beam in the direction of flow is a local detachment of the liquid metal flow from the wall.
  • the liquid jet expands transversely to the direction of flow.
  • a channel zone is created behind the narrowest point of the flow, within which the flow does not require a wall that completely surrounds it. The entry opening for the proton beam is thus provided at this point in the channel wall.
  • the expansion of the channel can, for fluidic reasons, extend to the pump in the flow circuit. However, it can also be limited to a distance which is sufficient to catch liquid metal which otherwise emerges in the flow direction from the inlet opening for the proton beam.
  • the channel guide in which a cross-sectional narrowing of the channel is provided perpendicular to the direction of flow, can accordingly be perpendicular to the respective case of need, it can also run horizontally or be inclined with respect to the horizontal.
  • the channel has a curvature which causes centrifugal forces in the liquid flow, through which a stable free surface of the liquid jet is formed in the area of the entry opening for the proton beam, the entry opening for the proton beam in the inner wall the channel curvature is provided.
  • the channel for the liquid flow in the region of the inlet opening for the proton beam is thus a curved piece of pipe which causes centrifugal forces directed outwards in the direction of the radius of curvature and away from the inlet opening.
  • the centrifugal forces in the curved part of the channel cancel the gravitational and other compressive forces acting on the stocking liquid to such an extent that the liquid cannot escape from the inlet opening for the proton beam.
  • the dimensioning and shape of the inlet opening for the proton beam are chosen taking into account that the free liquid surface takes on such a shape that the resultant from the gravitational and centrifugal force is perpendicular to the free liquid surface at every point so that the part of the free one Surface on which the proton beam occurs is almost vertical.
  • the liquid surface has the shape of a parabola as shown in FIG. 6 when the liquid flows within the curved pipe section at a spatially constant angular velocity. Wall friction effects can cause deviations from the parabolic shape, but they are not essential. The greater the flow velocity and thus the centrifugal force compared to the gravitational force, the greater the steepness of the parabola. As can also be seen from FIG. 6, the filling of the flow channel must not be complete.
  • a certain empty volume in the area of the curved pipe section is essential so that, given the steepness of the free surface determined by the flow velocity, the height Z o of the starting point of the free liquid surface on the channel wall in which the window is located is lower or at most the same height as that Bottom edge of the window is.
  • the approach height z o of the liquid surface becomes smaller the higher the flow velocity at a given local degree of filling. Conversely, the lower the local degree of filling, the smaller it is for a given flow rate.
  • the pump inlet should then expediently be at the lowest point of the circuit so that the pressure at this point is as high as possible.
  • the formation of a constant free surface of the flowing liquid in the region of the inlet opening for the proton beam in stationary operation is made considerably easier if, after an expedient further development of the target according to the invention, at the inlet opening for the proton beam extends over the width of the edge into the Flow protruding flow guide profile is provided, through which an additional lacing of the metallic liquid current is caused.
  • the channel wall is expediently shaped and / or a flow guide profile is provided such that the liquid only passes behind the downstream edge after passing through the area of the inlet opening for the proton beam creates the wall of the canal.
  • the depth of the channel for the liquid flow in the direction of the proton beam in the region of the entry opening for the proton beam in this embodiment of the target according to the invention at least according to the range of the protons in the metal used.
  • the range depends on the energy of the beam. The values in question are between 30 cm and 50 cm.
  • the local heat production density in the flowing liquid is not constant; on the contrary, it decreases exponentially within the proton beam with increasing distance from the surface of the liquid and quickly goes to zero after reaching the range of the proton beams. In the exponential range, the power density drops by more than an order of magnitude.
  • the high heat dissipation rate caused by convection is therefore only required in the front part of the target facing the proton beam source.
  • a very advantageous embodiment of the target according to the invention is that on the wall of the channel opposite the inlet opening for the proton beam, a solid body connected to a cooling system and usable as a target with a surface facing the inlet opening for the proton beam of at least the cross section of the proton beam is arranged.
  • the solid body mentioned above is part of the wall of the channel at the point opposite the entry opening for the proton beam.
  • the dimensions of the solid body are expediently such that the heat generated during the spallation is dissipated below the temperature by a cooling system provided for cooling the solid body, at which the material of the solid body melts and / or dissolves in the metal liquid.
  • the cooling takes place by gas or by a liquid. It is expedient to measure the cross-sectional dimension of the channel in the direction of the proton beam from the free surface of the liquid flow in order to reduce the part of the solid body which is effective in the spallation in depth.
  • a neutron multiplying material such as uranium, for example uranium-238, as the material for the solid body.
  • liquid metal 2 flows through a channel 1 with a rectangular cross section in the target according to the invention.
  • a lead or a lead bismuth eutectic can be used as the liquid metal.
  • the proton beam P enters the interior of the channel through an inlet opening 3, which is located in its direction and is arranged vertically in the channel wall, and strikes the flowing metal liquid there.
  • a cross-sectional constriction 4 is provided above the inlet opening 3 arranged in the vertically guided channel 1. This causes a constriction of the liquid flow 2 that extends over the inlet opening 3.
  • the liquid jet expands in the area of the cross sectional widening 5 of the channel 1 in a way that it only becomes after one predetermined distance behind the cross-sectional expansion on the wall of the channel 1. In this way it is achieved that no delimiting wall is required for the proton beam in the region of the inlet opening 3.
  • a liquid surface 6 is formed opposite the inlet opening 3 and has only a slight inclination with respect to the vertical.
  • the channel 1 It is not necessary to guide the channel 1 vertically, as shown in FIG. 1, but if necessary, the channel can also be arranged horizontally or inclined with respect to the horizontal. In these cases too, the inlet opening 3 for the proton beam P is arranged in a vertical channel wall.
  • FIG reproduced of the target according to the invention Another embodiment is shown in FIG reproduced of the target according to the invention.
  • the channel 1, which has a rectangular cross section, is curved for the liquid metal flow in the region of the inlet opening 3 for the proton beam P.
  • the inlet opening 3 for the proton beam P is arranged on the vertical inner wall of the channel 1.
  • centrifugal forces directed radially outward are exerted on the liquid flowing therein in the direction of the curvature radius.
  • the flow velocity of the liquid and curvature are coordinated so that the centrifugal forces in the curved part of the channel 1 cancel the gravitational and other compressive forces to such an extent that the metallic liquid 2 cannot emerge from the inlet opening 3 for the proton beam P.
  • the free surface 6 of the flowing metallic liquid 2 assumes such a shape that the resulting R from the gravitational force G and the centrifugal force Z is perpendicular to the surface at each point of the surface 6.
  • a flow guide profile 7 extending across the width of the window dimension perpendicular to the flow direction is arranged on the upstream edge of the inlet opening 3 for the proton beam P.
  • this flow guide profile has an edge which projects into the flow and narrows the cross section of the flow.
  • the channel wall is shaped in such a way that the liquid, after passing through the region of the inlet opening 3 for the proton beam P, only touches the wall behind the edge 8 of the inlet opening 3 located downstream and perpendicular to the flow of channel 1 creates.
  • a further embodiment of the target according to the invention is that the channel 1 for the liquid metal 2 has a reduced cross section in the direction of the extension of the proton beam P in the region of the inlet opening 3 for the proton beam, and that on the rear part of the channel 1, a solid body 11 suitable as a solid target is provided. As can not be seen from the drawing, the solid body 11 has at least the dimension of the cross section of the proton beam P.
  • a cooling system 12 To dissipate the heat generated during operation of the spallation neutron source in the solid body 11 is a cooling system 12, in which the cooling either by flowing gas or flowing Liquid is provided.
  • the cooling system 12 surrounds - as can be seen from FIG.
  • the dimensions are chosen so that the heat production in the solid body 11 remains sufficiently small and in such a way that the heat generated there can be dissipated below the melting temperature of the target material.

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
EP82105848A 1981-07-03 1982-07-01 Cible à métal liquide pour une source de neutrons de spallation Withdrawn EP0069341A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19813126191 DE3126191C2 (de) 1981-07-03 1981-07-03 Flüssigmetall-Target für eine Spallationsneutronenquelle
DE3126191 1981-07-03

Publications (1)

Publication Number Publication Date
EP0069341A1 true EP0069341A1 (fr) 1983-01-12

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EP82105848A Withdrawn EP0069341A1 (fr) 1981-07-03 1982-07-01 Cible à métal liquide pour une source de neutrons de spallation

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EP (1) EP0069341A1 (fr)
JP (1) JPS5810700A (fr)
DE (1) DE3126191C2 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6446522B1 (en) 1999-09-11 2002-09-10 Luk Lamellen Und Kupplungsbau Gmbh Automated transmission systems
WO2012069861A1 (fr) * 2010-11-26 2012-05-31 Szegedi Tudományegyetem Source de rayonnement à anode liquide
DE102011012737B3 (de) * 2011-02-24 2012-08-30 Forschungszentrum Jülich GmbH Targets für die Erzeugung von Sekundärstrahlung aus einer Primärstrahlung, Vorrichtung für die Transmutation radioaktiver Abfälle und Verfahren zum Betreiben
CN109257864A (zh) * 2018-11-19 2019-01-22 中国科学院近代物理研究所 一种上旋式液态金属无窗散裂靶构件
CN111430059A (zh) * 2020-04-08 2020-07-17 散裂中子源科学中心 一种可开展辐照实验的散裂中子源靶体

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3453175A (en) * 1966-06-10 1969-07-01 Ronald I Hodge System for extracting heat from a liquid metal target
US3993910A (en) * 1975-12-02 1976-11-23 The United States Of America As Represented By The United States Energy Research & Development Administration Liquid lithium target as a high intensity, high energy neutron source
FR2441993A1 (fr) * 1978-11-18 1980-06-13 Kernforschungsanlage Juelich Cible pour sources de neutrons de spallation

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3500098A (en) * 1965-04-27 1970-03-10 Ca Atomic Energy Ltd Intense neutron generator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3453175A (en) * 1966-06-10 1969-07-01 Ronald I Hodge System for extracting heat from a liquid metal target
US3993910A (en) * 1975-12-02 1976-11-23 The United States Of America As Represented By The United States Energy Research & Development Administration Liquid lithium target as a high intensity, high energy neutron source
FR2441993A1 (fr) * 1978-11-18 1980-06-13 Kernforschungsanlage Juelich Cible pour sources de neutrons de spallation

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
NUCLEAR INSTRUMENTS & METHODS *
NUCLEAR INSTRUMENTS & METHODS, Band 145, Nr. 1, August 1977, Seiten 49-76, Amsterdam (NL); *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6446522B1 (en) 1999-09-11 2002-09-10 Luk Lamellen Und Kupplungsbau Gmbh Automated transmission systems
WO2012069861A1 (fr) * 2010-11-26 2012-05-31 Szegedi Tudományegyetem Source de rayonnement à anode liquide
DE102011012737B3 (de) * 2011-02-24 2012-08-30 Forschungszentrum Jülich GmbH Targets für die Erzeugung von Sekundärstrahlung aus einer Primärstrahlung, Vorrichtung für die Transmutation radioaktiver Abfälle und Verfahren zum Betreiben
CN109257864A (zh) * 2018-11-19 2019-01-22 中国科学院近代物理研究所 一种上旋式液态金属无窗散裂靶构件
CN111430059A (zh) * 2020-04-08 2020-07-17 散裂中子源科学中心 一种可开展辐照实验的散裂中子源靶体

Also Published As

Publication number Publication date
JPS5810700A (ja) 1983-01-21
DE3126191C2 (de) 1983-07-14
DE3126191A1 (de) 1983-01-20

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Inventor name: FASSBENDER, JOSEF, DR.

Inventor name: MEISTER, GERHARD, DR.