Patents by Inventor Tihiro Ohkawa

Tihiro Ohkawa has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6396223
    Abstract: A cusp filter for altering a multi-species plasma to separate ions of different masses (M1 and M2) includes first and second axi-symmetric magnetic fields which are coaxial, have the same magnitude (B), and are oriented back-to-back to establish a null cusp. The null cusp is thus oriented perpendicular to the axis between the magnetic fields. An injector is provided for directing the plasma ions along the axis toward the null cusp to divert the ions (M1) away from the axis and prevent them from crossing the null cusp, while allowing the ions (M2) to cross the null cusp and proceed along the axis through the filter. In one embodiment, a cut-off mass, Mc, is determined such that M1<Mc<M2 with Mc=e2B2r2/2W where “e” is the ion charge, “r” is the radial distance of the ion from the axis, and W is its kinetic energy.
    Type: Grant
    Filed: April 21, 2000
    Date of Patent: May 28, 2002
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6386374
    Abstract: A multi-mass filter for separating particles of a multi-species plasma includes a chamber, which defines an axis. A radial electric field is crossed with a magnetic field (E×B) to move the particles of different mass (M1, M2 and M3) on respective trajectories into respective first, second and third regions. Specifically, particles M1 are confined in the first region, while both particles M3 and M2 are ejected from the first region into the second region and only the particles M3 are ejected from the second region into the third region.
    Type: Grant
    Filed: May 17, 2001
    Date of Patent: May 14, 2002
    Assignee: Archimedes Technology Group, Inc.
    Inventors: Robert L. Miller, Tihiro Ohkawa, Richard L. Freeman
  • Patent number: 6375860
    Abstract: The occurrence of internally-formed contaminants or negatively-charged particulates within a plasma is minimized by preventing such from becoming trapped in the plasma. The plasma is formed in a plasma chamber having control electrodes and reference electrodes. The control electrodes are biased with a negative potential. The plasma assumes a potential more positive than the control electrodes. The reference electrodes are then biased to be more positive than the plasma. Hence, negative ions or negatively-charged particulates in the plasma are attracted to the more positive reference electrodes, and thus escape the plasma without being trapped therein, and are not available to serve as nucleation or agglomeration points for contaminants. A pair of Helmholtz coils produce a magnetic field having magnetic field lines that run longitudinally between the control electrodes.
    Type: Grant
    Filed: March 10, 1995
    Date of Patent: April 23, 2002
    Assignee: General Atomics
    Inventors: Tihiro Ohkawa, Stanley I. Tsunoda
  • Publication number: 20020020657
    Abstract: A multi-mass filter for separating particles of a multi-species plasma includes a chamber, which defines an axis. A radial electric field is crossed with a magnetic field (E×B) to move the particles of different mass (M1, M2 and M3) on respective trajectories into respective first, second and third regions. Specifically, particles M1 are confined in the first region, while both particles M3 and M2 are ejected from the first region into the second region and only the particles M3 are ejected from the second region into the third region.
    Type: Application
    Filed: May 17, 2001
    Publication date: February 21, 2002
    Inventors: Robert L. Miller, Tihiro Ohkawa, Richard L. Freeman
  • Patent number: 6322706
    Abstract: A plasma filter for separating particles includes a hollow semi-cylindrical chamber that is enclosed by a wall. At least one plasma source is mounted in the chamber between the longitudinal axis of the chamber and the wall for generating a multi-species plasma containing light mass particles (M1) and heavy mass particles (M2). A magnetic coil is used to generate a magnetic field, Bz, in the chamber that is aligned parallel to the longitudinal axis, and electrodes at each end of the chamber generate an electric field, Er, in the chamber that is oriented perpendicular to the longitudinal axis. These crossed electric and magnetic fields rotate the multi-species plasma on a curved path around the longitudinal axis, and in a plane substantially perpendicular to the longitudinal axis, to separate M1 from M2.
    Type: Grant
    Filed: July 14, 1999
    Date of Patent: November 27, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6303007
    Abstract: A plasma injector for creating a plasma discharge includes a hollow, substantially cylindrical-shaped waveguide, and a coaxial dielectric loaded cavity. The waveguide is specifically dimensioned to establish a predetermined cut off wavelength in the waveguide. A microwave power generator is connected with the cavity to generate a resonant microwave in the cavity which will establish a TE mode electrical field in the waveguide. Importantly, the resonant microwave has a wavelength that is below the cut off wavelength in order to prevent a propagation of the microwave through the waveguide. The injector also includes a feed line for introducing a waste material into the waveguide. Specifically, the waste material interacts with the TE mode electrical field in the waveguide to vaporize the waste material and thereby create the plasma discharge.
    Type: Grant
    Filed: November 15, 1999
    Date of Patent: October 16, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6293406
    Abstract: A multi-mass filter for separating particles according to their mass-charge ratio includes a chamber for receiving a multi-species plasma that includes particles therein having different mass-charge ratios (with M1<M2<M3). Inside the chamber, which defines an axis, a radial electric field is crossed with a magnetic field (E≦B) to move the particles (M1, M2 and M3) on respective trajectories into respective first, second and third regions. For one embodiment, the filter is configured so that az2Bz is held constant in the expression for cut-off mass, Mcz=eaz2Bz2/(8Vctr). For this embodiment, only the heavier particles M3 are ejected into the third region (M3>Mc3) and only the intermediate particles M2 are ejected into the second region (M2>Mc2). In another embodiment, the radial electrical field is increased outwardly from the axis to a radial distance a2 (r2) at a first rate.
    Type: Grant
    Filed: August 21, 2000
    Date of Patent: September 25, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventors: Robert L. Miller, Tihiro Ohkawa, Richard L. Freeman
  • Patent number: 6294781
    Abstract: A device for segregating high-mass particles in a multi-species plasma from lower-mass particles has a chamber surrounded by a hollow annular shaped enclosure which defines a central axis. In a radial direction outwardly from the axis, the chamber includes a light mass collection section that is in fluid communication, through an intermediate section, with a filter section. A magnetic field, Bz, is oriented parallel to the central axis in the filter section, and the filter section has an outer wall which is at a distance slightly greater than a distance “a” from the central axis. An electric field is crossed with the magnetic field and is perpendicular to the central axis in the filter section. Further, there is zero potential on the outer wall of the filter section while there is a positive potential “V” on the inner wall of the filter section.
    Type: Grant
    Filed: April 23, 1999
    Date of Patent: September 25, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6287463
    Abstract: A collector cup for the collection and removal of the low-mass particles that exit from a plasma mass filter includes a cylindrical shaped wall, an internally cooled. getter plate and a plurality of internally cooled baffles. The baffles are concentrically mounted and are attached to the inside of the cylindrical wall, between the getter plate and the plasma mass filter thereby creating an enclosed volume that is defined by the getter plate, the baffles and the cylinder wall. Entryways are formed between the baffles to allow the gas formed at the baffles to enter the enclosed volume. When the ions and electrons exit from the filter, they collide with the cooler baffles, ano combine to form neutral atoms and vaporize. Once formed, the gas can pass through the entryways and into the enclosed volume where it can be condensed onto the surface of the temperature controlled getter plate.
    Type: Grant
    Filed: November 15, 1999
    Date of Patent: September 11, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6258216
    Abstract: An ion separator includes a plasma source for generating a multi-species plasma having ions of heavy mass (M2) and light mass (M1). Also included is an accelerator for accelerating these ions to a common velocity (vo) before they are injected into a hollow chamber. For this invention, the chamber can be configured as a toroid or a cylinder confining a curved path which generates a mass proportional drift velocity (ud) for each ion as it travels along the path. Consequently, ions will collide with the chamber wall, in sequence, according to their mass. This will be at predetermined arc lengths (L) along the path in the chamber. Specifically, ions of heavy mass (M2) will collide with the chamber wall before ions of light mass (M1). The ions can then be subsequently removed from the chamber wall. For one embodiment, the geometry of the chamber is established as a helix having a pitch angle which captures only heavy mass ions (M2) and allows ions of light mass (M1) to completely transit through the chamber.
    Type: Grant
    Filed: June 17, 1999
    Date of Patent: July 10, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6252224
    Abstract: A nuclear waste remediation system includes, in-line, an ionizer, an accelerator, an optional cooler and a separator. A pair of co-planar spaced-apart conductors extend the entire length of the system to establish a magnetic field which is perpendicular to the lengthwise dimension of the system. In the ionizer, the conductors are surrounded by casings which hold opposite alternating voltages that ionize a neutral gas. In turn, the ionized gas vaporizes nuclear waste to create a multi-species plasma. In the accelerator, cooler and separator, the conductors are surrounded by casings which carry the same dc current to thereby create an electric field which crosses with the magnetic field.
    Type: Grant
    Filed: December 18, 1998
    Date of Patent: June 26, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6251281
    Abstract: A plasma filter for separating positive ions from negative ions in a multi-species plasma includes a cylindrical shaped chamber. Magnetic coils surrounding the chamber generate a magnetic field that is aligned substantially parallel to the chamber's longitudinal axis. An electrode generates an electric field that is substantially perpendicular to the magnetic field to create crossed magnetic and electric fields inside the chamber. The inward directed electric field has a negative potential on the longitudinal axis and a substantially zero potential at the wall of the chamber. An injector injects the multi-species plasma into said chamber to interact with said crossed magnetic and electric fields.
    Type: Grant
    Filed: November 30, 1999
    Date of Patent: June 26, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6251282
    Abstract: A plasma mass filter using a helical magnetic field for separating low-mass particles from high-mass particles in a multi-species plasma includes a cylindrical outer wall located at a distance “a” from a longitudinal axis. Also included is a coaxial cylindrical inner wall positioned to establish a plasma chamber between the inner and outer walls. The magnetic field is generated in this chamber with an axial component (Bz) and an azimuthal component (B&thgr;), which interact together with an electric field to create crossed magnetic and electric fields. The electric field has a positive potential, Vctr, on the inner wall and a zero potential on the outer wall.
    Type: Grant
    Filed: December 8, 1999
    Date of Patent: June 26, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventors: Sergei Putvinski, Tihiro Ohkawa, Richard L. Freeman
  • Patent number: 6248240
    Abstract: A method for separating charged particles according to their mass requires providing a multi-species plasma in a chamber. The plasma includes both relatively low-mass charged particles (M1) and relatively high-mass charged particles (M2) which are influenced by crossed electric and magnetic fields (E×B) in the chamber. Specifically, the crossed fields (E×B) rotate the particles M1 and M2 in respective orbits that are characteristic of the mass of the particular particle. Inside the chamber, each charged particle has a respective cyclotron frequency (&OHgr;), and the plasma is maintained with a density wherein the collisional frequency (&ngr;) of particles in the chamber relates to the cyclotron frequency such that their ratio is greater than approximately one (&OHgr;/&ngr;≧1). Additionally, a collector is positioned to intercept the particles (M2) in their orbits and to thereby separate the particles (M2) from the particles (M1).
    Type: Grant
    Filed: December 15, 1999
    Date of Patent: June 19, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6235202
    Abstract: A tandem plasma mass filter for separating low-mass particles from high-mass particles in a multi-species plasma includes a cylindrical shaped wall which surrounds a hollow chamber. A magnet is mounted on the wall to generate a magnetic field that is aligned substantially parallel to the longitudinal axis of the chamber. Also, an electric field is generated which is substantially perpendicular to the magnetic field and which, together with the magnetic field, creates crossed magnetic and electric fields in the chamber. Importantly, the electric field has a positive potential on the axis relative to the wall which is usually zero potential. When a vapor is injected into the chamber and ionized, the resultant multi-species plasma interacts with the crossed magnetic and electric fields to eject high-mass particles into the wall surrounding the chamber.
    Type: Grant
    Filed: August 8, 2000
    Date of Patent: May 22, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6235250
    Abstract: A method and system for separating radioactive waste containing volatiles, into light ions and heavy ions, includes a loader/transporter for transferring the waste into a high vacuum environment in the chamber of a plasma processor. During this transfer, gases of the volatiles are released from the waste, collected in a holding tank, and subsequently ionized in the chamber. As the volatiles are ionized, the ions are directed by a magnetic field into contact with the waste to vaporize the waste. The waste vapors are then ionized in the plasma processor chamber to create a multi-species plasma which includes electrons, light ions and heavy ions. Within the chamber, the density of the multi-species plasma is established to be above its collision density in order to establish a substantially uniform velocity for all ions in the plasma. A nozzle accelerates the multi-species plasma to generate a fluid stream which is directed from the chamber toward an inertial separator.
    Type: Grant
    Filed: September 29, 1999
    Date of Patent: May 22, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6217776
    Abstract: A centrifugal filter for separating low-mass particles from high-mass particles in a rotating multi-species plasma includes a pair of annular shaped coaxially oriented conductors. The conductors are both aligned along a central axis and are spaced apart to create a plasma passageway between them. In this configuration, the conductors generate respective magnetic field components which interact to create a magnetic field having an increased magnitude in the passageway and a decreased magnitude along the central axis. The filter also includes an electric field which has a positive potential along the central axis and a decreasing potential in an outwardly radial direction from the central axis. Specifically, this electric field is crossed with the magnetic field in the passageway to confine low-mass particles in the passageway and to eject high-mass particles from the passageway.
    Type: Grant
    Filed: January 5, 2000
    Date of Patent: April 17, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6214223
    Abstract: A toroidal shaped plasma mass filter for separating heavy mass ions (M2) from light mass ions (M1) includes a platform having an annular shaped surface with a circular axis of rotation located midway between the inner and outer circumferences of the platform. An arched wall covers the platform to create a plasma chamber with the wall at least at a distance “a” from the axis of rotation. A plasma source is mounted on the platform in the chamber between the axis of rotation and the wall to generate a multi-species containing light mass particles (M1) and heavy mass particles (M2). In the chamber, the toroidal component, B&phgr;, of a helical magnetic field, B, is crossed with an electrical field, Er, having a positive potential Vctr along the axis of rotation.
    Type: Grant
    Filed: July 14, 1999
    Date of Patent: April 10, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6204510
    Abstract: An apparatus for altering the surface of a substrate includes a housing that is formed with an enclosed chamber having a first end and a second end. The chamber defines a longitudinal axis extending between the ends, and the substrate is positioned near the second end. A set of conductors are mounted in the chamber parallel to the longitudinal axis, and each conductor carries a current to establish a magnetic field (B) in said chamber. A first casing and a second casing surround each conductor with time alternating voltages being applied on the set of first casings to generate a plasma. The second casings are electrically insulated from a respective first casing so that a dc voltage can be applied to the second casings in a manner which ensures the potential of the resultant electric field (E) in the chamber is proportional to the magnetic flux.
    Type: Grant
    Filed: December 18, 1998
    Date of Patent: March 20, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa
  • Patent number: 6203669
    Abstract: A method and system for separating radioactive waste containing volatiles, into light ions and heavy ions, includes a loader/transporter for transferring the waste into a high vacuum environment in the chamber of a plasma processor. During this transfer, gases of the volatiles are released from the waste, collected in a holding tank, and subsequently ionized in the chamber. As the volatiles are ionized, the ions are directed by a magnetic field into contact with the waste to vaporize the waste. The waste vapors are then ionized in the plasma processor chamber to create a multi-species plasma which includes electrons, light ions and heavy ions. Within the chamber, the density of the multi-species plasma is established to be above its collision density in order to establish a substantially uniform velocity for all ions in the plasma. A nozzle accelerates the multi-species plasma to generate a fluid stream which is directed from the chamber toward an inertial separator.
    Type: Grant
    Filed: March 24, 1999
    Date of Patent: March 20, 2001
    Assignee: Archimedes Technology Group, Inc.
    Inventor: Tihiro Ohkawa