EP0362946A1 - Die Rückbeschleunigung von Sekundärelektronen begrenzende Ionenextraktions- und -beschleunigungseinrichtung in einer abgeschmolzenen Hochflup-Neutronenröhre - Google Patents

Die Rückbeschleunigung von Sekundärelektronen begrenzende Ionenextraktions- und -beschleunigungseinrichtung in einer abgeschmolzenen Hochflup-Neutronenröhre Download PDF

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Publication number
EP0362946A1
EP0362946A1 EP89202464A EP89202464A EP0362946A1 EP 0362946 A1 EP0362946 A1 EP 0362946A1 EP 89202464 A EP89202464 A EP 89202464A EP 89202464 A EP89202464 A EP 89202464A EP 0362946 A1 EP0362946 A1 EP 0362946A1
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EP
European Patent Office
Prior art keywords
electrode
acceleration
target
extraction
ion
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Withdrawn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
EP89202464A
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English (en)
French (fr)
Inventor
Henri Société Civile S.P.I.D. Bernadet
Xavier Société Civile S.P.I.D. Godechot
Claude Société Civile S.P.I.D. Lejeune
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.)
SODERN SA
Koninklijke Philips NV
Original Assignee
SODERN SA
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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 SODERN SA, Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical SODERN SA
Publication of EP0362946A1 publication Critical patent/EP0362946A1/de
Withdrawn legal-status Critical Current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
    • H05H3/00—Production or acceleration of neutral particle beams, e.g. molecular or atomic beams
    • H05H3/06—Generating neutron beams

Definitions

  • the invention relates to a device for extracting and accelerating ions in a sealed high-flux neutron tube containing a deuterium-tritium gas mixture under low pressure from which an ion source provides a beam (s) ( x) ionic (s) extracted and accelerated (s) at high energy by passing through an extraction and acceleration system, to be projected (s) on a target electrode and to produce there a fusion reaction resulting in an emission of neutrons.
  • Neutron tubes of the same kind are used in the techniques of examination of matter by fast, thermal, epithermal or cold neutrons: neutronography, analysis by activation, analysis by spectrometry of inelastic scatterings or radiative captures, scattering of neutrons etc. .
  • the d (3 H , 4 He ) n fusion reaction delivering 14 MeV neutrons is usually the most used due to its large cross section for relatively low ion energies.
  • the number of neutrons obtained per unit of charge passing through the beam is always increasing as the energy of the ions directed towards a thick target is itself increasing and this largely at the beyond the energies of the ions obtained in the sealed tubes currently available and supplied by a THT not exceeding 250 kV.
  • the erosion of the target by ion bombardment is one of the most determining.
  • Erosion is a function of the chemical nature and structure of the target on the one hand, the energy of the incident ions and their density distribution profile on the impact surface on the other.
  • the target consists of a hydrurable material (Titanium, Scandium, Zirconium, Erbium etc ...) capable of fixing and releasing large quantities of hydrogen without significant disturbance of its mechanical strength; the total quantity set is a function of the target temperature and the hydrogen pressure in the tube.
  • the target materials used are deposited in the form of thin layers, the thickness of which is limited by problems of adhesion of the layer to its support.
  • One way to delay erosion of the target is, for example, to form the absorbent active layer from a stack of identical layers isolated from each other by a diffusion barrier. The thickness of each of the active layers is of the order of the depth of penetration of the deuterium ions coming to strike the target.
  • Another way of protecting the target and therefore of increasing the lifetime of the tube consists in acting on the ion beam so as to improve its density distribution profile on the impact surface. At a constant total ion current on the target electrode, which results in a constant neutron emission, this improvement will result from a distribution as uniform as possible of the current density over the entire surface offered by the target for bombardment. ions.
  • One of the ways to reduce this maximum density is to use the divergence of the beam in the sliding space between the point of convergence and the target. Any increase in this space by a factor x of the ion path results in a reduction of the type in 1 / x2 of the maximum bombardment density.
  • the pressure of the deuterium-tritium mixture necessary to obtain the current of ions is first order, the same throughout the tube.
  • the ions extracted and accelerated towards the target will react with the molecules of the gas to produce ionization, dissociation and charge exchange effects resulting on the one hand in a reduction in the average energy of the ions on the target, that is to say a reduction in the production of neutrons and on the other hand the formation of ions and electrons which are then accelerated and will bombard the source of ions or the electrodes of the tube.
  • the object of the invention is to provide a structure for which these reactions no longer have detrimental repercussions on the operation of the tube. For that, it is enough to avoid that the electrons created by the ions of the beam can "go up" towards the source of ions where they would deposit a significant energy. It is therefore necessary to push them back inside the sliding space where they acquire only a very low energy and to collect them on the electrodes limiting this space.
  • said acceleration system comprises an addition electrode polarized so as to limit the re-acceleration towards the source of the secondary electrons created by ionization of the gas on the path of said beam (s) inside the space between said extraction and acceleration system and said target electrode, which makes it possible to increase said space to greatly reduce the inhomogeneities of the ion bombardment.
  • An embodiment of the device of the invention consists of a last acceleration electrode brought to the same potential as the target and said additional electrode playing the role of electron repulsion electrode, polarized negatively with respect to said last electrode acceleration and whose plane is located near and downstream of the exit plane of the last acceleration electrode in the equipotential space accelerator-target electrode.
  • said device of the invention comprises a last ion acceleration electrode polarized negatively with respect to the target electrode to play the role of electron repulsion electrode.
  • Said additional electrode disposed near and downstream of the exit plane of said last ion acceleration electrode, is polarized at the same potential as the target. The electrons are collected by the target and the additional electrode.
  • the devices according to the invention do not cause any appreciable disturbance in terms of the operation of the tube when the sliding space is increased.
  • the energetic ions lose very little energy during ionizing shocks (of the order of 10 ⁇ 4) and, during charge exchanges, they transform into fast neutrals with the same energy as the incident ion.
  • the electrons and the ions created in the sliding space consequently have only a weak energy and taking into account the polarizations of the electrodes are captured by them and the deposited energies are reduced (of the order of 1% of the energy dissipated on the target).
  • FIG. 1 shows the main basic elements of a sealed neutron tube 11 containing a gaseous mixture under low pressure to be ionized such as deuterium-tritium and which comprises an ion source 1 and an acceleration electrode 2 between which there is a very high potential difference allowing the extraction and the focusing of the ion beam 3 and its projection on the target 4 where the fusion reaction takes place resulting in an emission of neutrons at 14 MeV for example.
  • a sealed neutron tube 11 containing a gaseous mixture under low pressure to be ionized such as deuterium-tritium and which comprises an ion source 1 and an acceleration electrode 2 between which there is a very high potential difference allowing the extraction and the focusing of the ion beam 3 and its projection on the target 4 where the fusion reaction takes place resulting in an emission of neutrons at 14 MeV for example.
  • the ion source 1 secured to an insulator 5 for the passage of the THT supply connector is a Penning type source for example, consisting of a cylindrical anode 6, of a cathode structure 7 to which is incorporated a magnet 8 with an axial magnetic field which confines the ionized gas 9 around the axis of the anode cylinder and whose lines of force 10 show a certain divergence.
  • An ion emission channel 12 is formed in said cathode structure opposite the anode.
  • FIG. 2a shows the profile of the density J of ion bombardment in any radial direction Or, from the point of impact 0 of the central axis of the beam on the surface of the target for standard optics with a single electrode .
  • the shape of this profile highlights the inhomogeneous nature of this beam whose very high density in the central part decreases rapidly when one moves away from it.
  • erosion takes place as a function of the bombardment density and the entire layer of hydrurable material of thickness e deposited on a substrate S is saturated with a deuterium-tritium mixture.
  • the depth of penetration of the deuterium-tritium energy ions represented in dotted lines is effected over a depth which is a function of this energy.
  • the erosion of the layer is such that the penetration depth l2 is greater than the thickness e in the most bombarded part; a part of the incident ions is implanted in the substrate and very quickly the atoms of deuterium and tritium are in supersaturation.
  • FIG. 3a shows diagrammatically a neutron tube comprising an ion source 12 of the multicellular multi-beam Penning type whose cylindrical anode 6 pierced with juxtaposed multitrous 6a, 6b, ... 6e is brought to a higher potential of the order of 4 kV to that of cathode 7 itself brought to a very high voltage of 250 kV for example.
  • the ion beams 3a, 3b, ... 3e coming from the emission channels 7a, 7b ... 7th practiced in the cathode opposite the corresponding anode holes are projected onto the target 4 by means of the acceleration electrode 2.
  • the section of beam intercepted by the target depends on the divergence of the trajectories and especially on the distance from the target to the point of convergence.
  • FIG. 3a illustrates this property by a judicious choice of the position of the target.
  • One way to obtain a more homogeneous density distribution at the impact of the global beam on the target is to move the latter away from the source, from position A to position B for example, so that there is overlap elementary beams.
  • the device of the invention makes it possible to repel the secondary electrons emitted by the target as well as those created by ionization of the gas.
  • this is achieved by placing an additional electrode 13 suitably polarized near the acceleration electrode in the sliding space between this electrode and the target, which then makes it possible to fully benefit from the effect of distance from the target.
  • This additional electrode is brought to a negative potential (-5 kV for example) compared to those of the acceleration electrode and the target grounded and made of a refractory material to prevent its heating by the inter-electrode currents in the target space-accelerating electrode.
  • FIG. 4 shows the potential distribution along the axis of the ion beam for the device of FIG. 3.
  • the positions of the target C, the suppressor electrode ES1, the accelerating electrode EA1 and the source S1 were plotted on the abscissa on the one hand for a certain configuration of neutron tube and on the other hand the positions of the suppressor electrode ES2, accelerator electrode EA2 and source S2 for another configuration of neutron tube corresponding to a doubling of the sliding space.
  • the level of potential VS of the suppressor electrode has been indicated on the ordinate.
  • the curves in solid line and in broken lines represent respectively the difference between the potential V along the axis of the ion beam and the potential Vc of the target for the two configurations.
  • FIG. 5 represents a second variant of the device of the invention in which a target-carrying electrode 14 in the form of a well, or which may have a structure with holes, at the same potential as the target 4 is arranged in the vicinity of the electrode d acceleration 2 in the space between this electrode and the target.
  • the electron repulsion effect is achieved by polarizing the acceleration electrode at a slightly negative potential Va relative to the target.
  • FIG. 6 A graph similar to that of FIG. 4 illustrates in FIG. 6, for this second variant of the device, the variation of the potential V-Vc along the axis of the ion beam.
  • the positions ER1 and ER2 of the rim of the target-carrying electrode placed near the acceleration electrode were plotted on the abscissa. The above considerations for the graph in Figure 4 remain valid.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Particle Accelerators (AREA)
EP89202464A 1988-10-07 1989-10-02 Die Rückbeschleunigung von Sekundärelektronen begrenzende Ionenextraktions- und -beschleunigungseinrichtung in einer abgeschmolzenen Hochflup-Neutronenröhre Withdrawn EP0362946A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8813186A FR2637725A1 (fr) 1988-10-07 1988-10-07 Dispositif d'extraction et d'acceleration des ions limitant la reacceleration des electrons secondaires dans un tube neutronique scelle a haut flux
FR8813186 1988-10-07

Publications (1)

Publication Number Publication Date
EP0362946A1 true EP0362946A1 (de) 1990-04-11

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EP89202464A Withdrawn EP0362946A1 (de) 1988-10-07 1989-10-02 Die Rückbeschleunigung von Sekundärelektronen begrenzende Ionenextraktions- und -beschleunigungseinrichtung in einer abgeschmolzenen Hochflup-Neutronenröhre

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US (1) US5112564A (de)
EP (1) EP0362946A1 (de)
JP (1) JPH02148700A (de)
FR (1) FR2637725A1 (de)

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Publication number Priority date Publication date Assignee Title
IT1239133B (it) * 1990-04-06 1993-09-28 Ariete Srl Ferro da stiro a vapore, in particolare del tipo a goccia
FR2666477A1 (fr) * 1990-08-31 1992-03-06 Sodern Tube neutronique a flux eleve.
FR2710782A1 (fr) * 1993-09-29 1995-04-07 Sodern Tube neutronique à confinement magnétique des électrons par aimants permanents et son procédé de fabrication.
US6441569B1 (en) 1998-12-09 2002-08-27 Edward F. Janzow Particle accelerator for inducing contained particle collisions
US6922455B2 (en) * 2002-01-28 2005-07-26 Starfire Industries Management, Inc. Gas-target neutron generation and applications
CA2575505A1 (en) * 2004-08-06 2006-02-16 Grain Processing Corporation Frozen food products comprising holocellulose and methods for their manufacture
JP5673916B2 (ja) * 2009-02-24 2015-02-18 独立行政法人日本原子力研究開発機構 放射性同位元素の製造方法及び装置
JP5522568B2 (ja) * 2009-02-24 2014-06-18 独立行政法人日本原子力研究開発機構 放射性同位元素の製造方法及び装置
JP5522565B2 (ja) * 2009-02-24 2014-06-18 独立行政法人日本原子力研究開発機構 放射性同位元素の製造方法及び装置
JP5522566B2 (ja) * 2009-02-24 2014-06-18 独立行政法人日本原子力研究開発機構 放射性同位元素の製造方法及び装置
JP5522563B2 (ja) * 2009-02-24 2014-06-18 独立行政法人日本原子力研究開発機構 放射性モリブデンの製造方法及び装置
JP5522567B2 (ja) * 2009-02-24 2014-06-18 独立行政法人日本原子力研究開発機構 放射性同位元素の製造方法及び装置
JP5522564B2 (ja) * 2009-02-24 2014-06-18 独立行政法人日本原子力研究開発機構 放射性同位元素の製造方法及び装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3448314A (en) * 1965-03-11 1969-06-03 Atomic Energy Authority Uk Neutron generators
US3569756A (en) * 1964-08-18 1971-03-09 Philips Corp Ion source having a plasma and gridlike electrode
NL7707357A (en) * 1977-07-04 1979-01-08 Philips Nv Anode for neutron generator ion source - has holes aligned to outlets in cathode converging beams on target
US4529571A (en) * 1982-10-27 1985-07-16 The United States Of America As Represented By The United States Department Of Energy Single-ring magnetic cusp low gas pressure ion source

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3014132A (en) * 1959-01-02 1961-12-19 High Voltage Engineering Corp Loss current diminisher for compact neutron source

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3569756A (en) * 1964-08-18 1971-03-09 Philips Corp Ion source having a plasma and gridlike electrode
US3448314A (en) * 1965-03-11 1969-06-03 Atomic Energy Authority Uk Neutron generators
NL7707357A (en) * 1977-07-04 1979-01-08 Philips Nv Anode for neutron generator ion source - has holes aligned to outlets in cathode converging beams on target
US4529571A (en) * 1982-10-27 1985-07-16 The United States Of America As Represented By The United States Department Of Energy Single-ring magnetic cusp low gas pressure ion source

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JPH02148700A (ja) 1990-06-07
FR2637725A1 (fr) 1990-04-13
US5112564A (en) 1992-05-12

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