Classifications

• • 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
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/24—Generating plasma
  • H05H1/46—Generating plasma using applied electromagnetic fields, e.g. high frequency or microwave energy
• • 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
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/02—Arrangements for confining plasma by electric or magnetic fields; Arrangements for heating plasma
  • H05H1/10—Arrangements for confining plasma by electric or magnetic fields; Arrangements for heating plasma using externally-applied magnetic fields only, e.g. Q-machines, Yin-Yang, base-ball

Definitions

• the present invention relates to a device for creating a magnetic field inside an enclosure.
• the present invention relates to a device intended to create a magnetic field in order to confine a plasma inside an enclosure.
• Plasmas are ionized gases, electrically neutral mixtures of ions and electrons, used in industry, in particular, to make very thin deposits on surfaces.
• Plasma can be created by various methods, for example, from non-ionized atoms which are brought, in the form of vapor, into an enclosure in which there is a magnetic field having a determined configuration.
• the term configuration takes into account both the spatial geometry of the magnetic field and its intensity at any point in the space where it prevails.
• the configuration of the field depends mainly on the arrangement of the magnetic field generating means around the enclosure. By placing them appropriately, it is possible to obtain a field having the desired configuration in the enclosure.
• the atoms are ionized, for example, by energetic electrons called "heated by a high frequency wave propagating in the enclosure and coupled with the magnetic field B reigning in the enclosure, according to the relation:
• the electrons, torn from the nuclei of atoms under the effect of the high frequency wave, are subjected to the magnetic field B and describe then spiral movements while colliding with the other surrounding atoms, thus causing their ionization.
• the plasma is thus confined in a limited volume delimited by the magnetic field B, that is to say that it serves, in a way, as an intangible container plasma.
• the shocks between atoms and electrons accelerate the ionization of atoms of non-ionized or already ionized gases. It is thus possible to tear off several electrons from the same atom and to form multi-charged ions.
• the magnetic field prevailing in the enclosure is produced by permanent magnets or coils placed outside the enclosure. In general, the intensity of the field used is between 0.01 T and several Teslas. The fields generated by these magnets or coils only allow a magnetic field of determined configuration to be created, only in very small volumes, of the order of a few liters.
• This cooling device requires the superconductive coils to be placed at a distance of at least 5 cm from the walls of the enclosure, which considerably hinders the establishment of a magnetic field of arbitrary configuration inside the enclosure.
• the object of the present invention is to solve the technical problems posed by the prior art.
• This object is achieved by means of a device intended to create a magnetic field inside an enclosure delimited by a wall and provided with at least one orifice for the entry of an atomic material, in vapor phase and at least one orifice for extracting ions, electrons or electromagnetic radiation from the ionization of this material, comprising:
• magnetic field generating means capable of at least partially surrounding the enclosure.
• These magnetic field generating means are placed at a distance from the wall of the enclosure of between a few millimeters and a distance of the order of the largest dimension of the enclosure, and comprise at least one coil produced with a material having superconductive properties between 16 K and 273 K as well as a cryogenic system intended to maintain said magnetic field generating means at this temperature.
• the magnetic field generating means are arranged at a distance from the wall of the enclosure comprised, approximately, between 1 mm and 50 mm.
• the device using superconductive materials between 16 K and 273K it is then possible to dispense with the refrigeration device using liquid helium.
• a cryogenic system of the "Cryocooler” type which not only allows the coils to be brought together, but also has the advantage of being less bulky, less expensive and more flexible and safer to use than a helium cryogenic system.
• the cost of the installation is thus greatly reduced and the safety of the installation improved.
• a device using a conventional cryogenic helium system generally occupies a volume of 1 m 3 and weighs several hundreds of pounds.
• a device using a cryogenic system of the "Cryocooler” type occupies a volume of only a few tens of liters.
• Such a device can be used, for example, to confine a plasma produced in another device.
• the very small distance between the wall and the generating means makes it possible to establish, at any point situated inside an enclosure of any volume, a magnetic field of the order of 1 to 5 T sufficient for multiple applications.
• this device further comprises a system for injecting the atoms into the enclosure and a system for extracting the ions and electrons from the plasma contained in the enclosure.
• a system for injecting the atoms into the enclosure and a system for extracting the ions and electrons from the plasma contained in the enclosure.
• Such a device can then be integrated into the structure of various devices.
• this device will also comprise a system for ionizing the atoms injected into the enclosure.
• the device will also comprise a device for guiding a high frequency wave inside said enclosure.
• ECR electronic cyclotron resonance
• such a device can further comprise an extraction system making it possible to obtain a wide beam. It could then be used, for example, for the production of wide beams, or the production of an apparatus intended to treat surfaces on an industrial scale.
• the volume magnetized by the device according to this As the invention can be very important, the part to be treated can be completely immersed in the plasma. Its processing is then much easier and faster than with a beam which must be moved on the surface of said part. The deposit thus made is perfectly uniform.
• the device according to the present invention further comprises a system for extracting heavy elements which may be contained in the plasma.
• the device according to the present invention may also, according to a particular embodiment, comprise displacement members of at least part of the means generating the magnetic field.
• the device according to the present invention further comprises means for regulating the intensity of the electric current flowing through at least one winding.
• means of regulation can be, for example, simple potentiometers. It is possible to combine means for regulating the intensity of the current in the winding with one or more members for moving said winding or other magnetic field generating means.
• One use of the device according to the present invention is the production of apparatuses intended for the production of plasmas.
• FIG. 1a shows a particular embodiment of the present invention
• Figure 1b shows the different configurations that can be obtained using the device of Figure 1a;
• FIG. 2a shows a particular embodiment, used for the production of a plasma
• FIG. 2b represents an example of configuration of the magnetic field inside the enclosure
• FIG. 3a shows a second embodiment of the present invention, used to produce multi-charged ions
• FIG. 3b represents an example of configuration of the field used
• FIG. 4 schematically shows a third embodiment used in a system for producing large and uniform plasma for the industrial treatment of large areas
• FIG. 5a schematically shows a fourth embodiment used, for example, for the manufacture of an apparatus for producing X-rays
• FIG. 5b represents an example of a preferred configuration of the magnetic field used in this device
• FIG. 1a represents a particular embodiment making it possible to obtain a magnetic field B prevailing in an enclosure 10 and having a cylindrical geometry with respect to an axis of symmetry z.
• Five coils, 20, 21, 22, 23 and 24 create an axial magnetic field Bz, that is to say parallel to the axis z.
• the coils 20, 21, 22, 23 and 24 are contained in an envelope 30 connected, for example, to a Cryocooler (not shown in FIG.
• FIG. 1b represents the different configurations of the axial component that it is possible to obtain with such a device, by varying the intensity of the current flowing through the windings.
• Each curve represents the shape of the module of the axial component of the magnetic field. prevailing in the enclosure as a function of the position on the z axis The maximum intensity of this component is of the order of a few teslas and depends on the cyclotron resonance frequency
• the curves 100, 101 and 102 all present two maxima of different values and a minimum value which can form a plateau, as is the case on curve 102
• Curve 103 is almost plane
• Curves 104 and 105 have only a maximum value whose position on the z axis is adjustable by adjusting the intensity of the current in the coils, for example, by means of potentiometers
• the intensity of the current in said coils will, for example, be of the order of a few hundred amperes
• FIG. 2a schematically represents an embodiment of the present invention
• Five coils 20, 22, 24, 26 and 28 of superconductive materials maintained at a temperature between 16 K and 273 K are disposed respectively in an envelope 30 connected to a cryogenic system suitable 40, for example, a Cryocooler which maintains them at a temperature of the order of 30 K, the envelope 30 itself being at ambient temperature
• a cryogenic system suitable 40 for example, a Cryocooler which maintains them at a temperature of the order of 30 K, the envelope 30 itself being at ambient temperature
• a cryogenic system suitable 40 for example, a Cryocooler which maintains them at a temperature of the order of 30 K
• the envelope 30 itself being at ambient temperature
• a cryogenic system suitable 40 for example, a Cryocooler which maintains them at a temperature of the order of 30 K
• the envelope 30 itself being at ambient temperature
• separate envelopes for each of the windings connected to independent cryogenic systems surround the enclosure 10 comprising an inlet orifice 12 for the material in
• This ionization system is, for example, either a filament, a waveguide, or an optical system making it possible to bring a high frequency wave into the enclosure 10. It is also possible to provide a number of windings suitable for the dimensions of the enclosure to be magnetized.
• a conventional extraction system 50 intended to extract the components of the plasma generated in the enclosure 10 and an injection system 52 will complete the device which will then be able to receive a plasma or atoms inside the enclosure 10
• the field then advantageously has the configuration shown in FIG. 2b.
• the magnetic field has at least one value at which electronic cyclotron resonance is obtained with any field geometry.
• the coils are arranged as close as possible to the plasma chamber in order to minimize the magnetized volume.
• FIG. 3a schematically represents an apparatus used to generate plasmas of multi-charged ions, that is to say comprising several positive charges.
• the device further comprises a system for generating a multipolar magnetic field 60 comprising superconductive coils or permanent magnets and a system for guiding a high frequency wave (not shown in FIG. 3a) inside the enclosure 10 so as to generate plasma by electronic cyclotron resonance.
• the windings 20, 21 and 22 are preferably placed around the enclosure 10 and placed at a distance I of the order of a few millimeters.
• Each winding is contained in an envelope 30, 31, 32 connected to a cryogenic system. Several cryogenic systems can also be provided, one for each envelope.
• FIG. 3b represents a preferred configuration of the magnetic field along a section of the chamber along an axis perpendicular to the axis z located in the middle of the enclosure in the case of a magnetic field B having a cylindrical symmetry with respect to this axis z.
• the magnetic field module B has two maximums B1 and B2 surrounding a minimum value B3 intermediate to these two maxima.
• the value of these maxima is greater than the value B ECR for which the cyclotronic resonance is obtained.
• This value B ECR depends on the nature of the atoms used and the high frequency wave brought into the enclosure 10.
• the minimum value B3 is less than B ECR -
• FIG. 4 represents an embodiment of the present invention intended to treat surfaces using large and uniform plasmas in density .
• FIG 4 for simplicity, a single coil 20 has been shown.
• This coil 20 is contained in an envelope 30 connected to an appropriate cryogenic system, maintaining it at a temperature between 16 K and 273 K.
• the extraction system 70 comprises a grid 74 of so as to produce a wide plasma beam which will be applied to a fixed or mobile substrate S under the device.
• the surface to be treated of the substrate S is located at an adjustable distance R, of the order of several tens of centimeters, for example.
• R adjustable distance
• the waveguiding system comprises several waveguides 200, 201, 202, 203, 204, 205, 206, and 207 arranged along the enclosure 10 and intended to bring there a wave of frequency greater than 900Mhz, with a uniform distribution of the power density of this HF wave.
• the magnetic field B prevailing in the enclosure 10 is intense and uniform, preferably its intensity is greater than 0.01 T.
• the magnetizable volume can be extremely large, it is possible to extract long and wide beams representing an area of approximately 1 m 2 . It is then possible to treat very large areas quickly and obtain a regular deposit.
• Figure 5a schematically shows a fourth embodiment of the present invention which can be used for the production of X-rays.
• the device comprises a system 58 for guiding a wave of higher frequency, preferably at 2.45 Ghz, inside the enclosure 10.
• the generator means comprising several windings, 20, 21, 22, 23, 24 are arranged along the z axis.
• the magnetic field generated in the enclosure assuming that it has an axi-cylindrical geometry, to simplify its representation, has a configuration preferably similar to that shown in FIG. 5b.
• the magnetic field module presents along the axis of symmetry z two maxima B1 and B2, at values greater than R ECR and a plateau, B3, whose value is equal to R ECR -
• the atoms confined between these two maxima suffer shocks between themselves and with the electrons that have been torn from them.
• An electron strongly linked to the nucleus is torn from the atom, an electron located near the nucleus but less linked to it than the electron previously torn off fills the void left by the preceding electron.
• This passage is carried out with an emission of high energy photons such as X-rays.
• This type of device also makes it possible to obtain a magnetic field of arbitrary geometry in the enclosure 10.
• Each embodiment described above may further include members for moving at least part of the magnetic field generating means. It is then possible to modulate the configuration of the magnetic field prevailing in the enclosure by moving the magnetic field generating means. It is thus possible to modify, at any point situated inside the enclosure, the direction of the magnetic field vector as well as its intensity.
• the windings are fixed on displacement members, for example in translation along the plasma chamber, comprising for example screws allowing precise movement of the windings. This modulates the configuration of the magnetic field B prevailing in the enclosure. It is also possible to simultaneously equip the device with potentiometers intended to regulate the intensity of the current flowing through the windings.
• the generator means being close to the wall, it is easy to modify with finesse and precision the configuration of the magnetic field prevailing in the enclosure, that is to say, its intensity and its geometry. We can thus create, in any volume, a magnetic field of any geometry.
• the modulation of the magnetic field has several advantages.
• the chamber has dimensions depending on the high frequency wave which ionizes the atoms.
• the magnetic field is also coupled to this wave.
• the fact of being able to modulate the intensity of the B field makes it possible to use waves of different frequencies and thus to obtain electronic cyclotron resonance for several kinds of ions originating from different elements.
• the shape of the windings can be variable, namely, for example, circular or square, depending on the field to be created in the enclosure 10.
• the magnetic configuration of the field also determines the type of ions formed.
• the device according to the present invention therefore makes it possible to produce different configurations of fields adapted to the formation of different types of ions.

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• 1998
  • 1998-05-26 FR FR9806579A patent/FR2779315B1/fr not_active Expired - Fee Related
• 1999
  • 1999-05-26 EP EP99920915A patent/EP1080613B1/de not_active Expired - Lifetime
  • 1999-05-26 JP JP2000551587A patent/JP2002517078A/ja active Pending
  • 1999-05-26 WO PCT/FR1999/001223 patent/WO1999062307A1/fr active IP Right Grant
  • 1999-05-26 DE DE69915282T patent/DE69915282T2/de not_active Expired - Fee Related
  • 1999-05-26 AU AU38313/99A patent/AU3831399A/en not_active Abandoned

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