US3895254A - Charged particle accelerator with integral transformer and shielding means - Google Patents

Charged particle accelerator with integral transformer and shielding means Download PDF

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Publication number
US3895254A
US3895254A US484339A US48433974A US3895254A US 3895254 A US3895254 A US 3895254A US 484339 A US484339 A US 484339A US 48433974 A US48433974 A US 48433974A US 3895254 A US3895254 A US 3895254A
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United States
Prior art keywords
receptacle
charged particle
particle accelerator
conductor layer
voltage
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Expired - Lifetime
Application number
US484339A
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English (en)
Inventor
Yoshihisa Minamikawa
Susumu Ozasa
Shoji Kamimura
Yasushi Saito
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Hitachi Ltd
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Hitachi Ltd
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Publication date
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement, ion-optical arrangement
    • H01J37/06—Electron sources; Electron guns
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/248—Components associated with high voltage supply

Definitions

  • a charged particle accelerator wherein a receptacle surrounding an accelerating tube is made of an insulator, a grounded conductor layer is provided on the outside surface of the receptacle, at least one transformer is formed by opposing a primary coil on the outside and a secondary coil on the inside with the wall of the receptacle held therebetween, a conductor layer is provided on the inside surface of the receptacle at the transformer forming portion, a corona shield is provided at an end part of the inside conductor layer, and the induced voltage of the secondary coil is rectified and smoothed so as to apply the resultant voltage to a Wehnelt cylinder as a bias voltage.
  • a continuously variable bias voltage can be obtained by regulating the applied voltage on the primary side of the transformer.
  • a bias voltage to be applied between a filament and a Wehnelt cylinder which is provided around the filament and which serves to regulate the amount of electron rays from the filament the value of a bias resistance disposed between the filament and the Wehnelt cylinder is mechanically adjusted by an external control rod.
  • the bias voltage is bestowed by the self-bias system owing to the bias resistance.
  • the bias voltage V has the relation of V R] where 1 denotes the amount of electron rays emitted from the filament and R the bias resistance value.
  • the amount of electron rays I is also a function of the bias voltage V. It has been accordingly impossible to pro vide an arbitrary bias voltage or a continuously variable bias voltage.
  • the alignment of the filament, the change-over operation in the case of employing a plurality of filaments, etc., are involved in the high voltage portion in addition to the change-over operation of the bias resistance. All the adjustments have hitherto been made mechanically by means of control rods.
  • the use of the control rod increases the chance of a creepage of current along the insulation portion which is most unstable in the high voltage situation. Therefore, the reliability for the application of a high voltage becomes less, and the structure becomes complicated.
  • An object of this invention is to obviate the disadvantages of the prior art, and to provide a charged particle accelerator which reduces the creepage insulation portion and which can provide a continuously variable bias voltage.
  • the fundamental construction of the charged particle accelerator according to this invention lies in provision of a receptacle surrounding an accelerating tube, which receptacle is made of an insulator.
  • a grounded conductor layer is provided on the outside surface of the receptacle, at least one transformer is formed by oppositely disposing the primary coil on the outside and the secondary coil on the inside with the receptacle wall held therebetween, and the induced voltage of the secondary coil is rectified and smoothed so as to apply the resultant voltage to a Wehnelt cylinder as a bias voltage.
  • a further construction of the charged particle accelerator lies in that a conductor layer is provided on the inside surface of the receptacle at the transformer forming portion, and that its end part is shielded against corona.
  • FIG. 1 is a sectional view of a prior art multistage accelerator which is the electron source of an electron microscope;
  • FIG. 2 is a sectional view of a multistage accelerator for an electron microscope as shows an embodiment of this invention
  • FIG. 3 is a diagram showing a circuit for the bias voltage and filament heating portion of the device in FIG. 2, and
  • FIG. 4 shows another embodiment of this invention.
  • FIG. 1 shows the schematic construction of the prior art charged particle accelerator.
  • numeral 1 designates an accelerating tube, 2 a divided resistance, 3 a receptacle, 4 the internal space of the receptacle having an insulating gas atmosphere, 5 a supply and exhaust port for the insulating gas, 6 a Wehnelt cylinder for adjusting the amount of emitted electrons, 7 a filament cathode forming an electron or ion source, 8 an electron beam, 9 an electron microscope body, 10 a bias resistance determining the amplitude of the current supplied to the cylinder 6, 11 a control rod for changing over the bias resistance, 11 a control rod for aligning the filament, 12 a high voltage cable, 13 a cable head, 14 a filament transformer, and 15 a filament power source.
  • a high voltage is applied from a high voltage generator (not shown) through the high voltage cable 12 as well as the cable head 13 to the Wehnelt cylinder 6.
  • the electron beam 8 emitted from the filament 7 passes through the accelerating tube 1 to the electron microscope body 9.
  • the heating of the filament 7 is executed by the filament power source 15 applying heating current through the filament transformer 14 disposed within the cable head.
  • FIG. 2 shows an embodiment of this invention, and is a transverse sectional view of a charged particle accelerator.
  • the same symbols as in FIG. 1 indicate the same constituent members.
  • the accelerating tube I is stored in the receptacle 31 which is made of an insulator, for example, an epoxy resin. Since the receptacle 31 is made of an insulating material, a voltage is in Jerusalem in the surface thereof by the high voltage applied to the accelerating tube, which is dangerous. In order to avoid the danger resulting therefrom and also to make the electric field of the insulator portion uniform, the outside surface is coated with a conductive paint 16, which is grounded.
  • a transformer is provided which is composed of the primary coil 17 disposed at the top part of the receptacle 31, and the secondary coil 18 insulated therefrom by the receptacle wall. Power is supplied from a power source 19 to this transformer, and power thus induced in the secondary coil is fed as the bias voltage by a circuit shown in FIG. 3. More specifically, the pwer induced in the secondary coil 18 is converted to a DC. voltage through a smoothing circuit 20.
  • bias voltage is applied between the filament 7 and the Wehnelt cylinder 6 in the form of the bias voltage, so as to adjust the amount of the electron rays 8. Since the bias voltage is applied through the transformer, arbitrary and continuous adjustments are possible from outside the receptacle by merely varying the bias voltage. By way of example, bias voltages of 0.1 V to 2,000 V are obtained. The spacing between the primary coil 17 and the secondary coil 18 becomes small by slenderizing the top part of the receptacle 3], so that the transmission efficiency of the transformer is enhanced. Since the secondary coil is at the high voltage potential as illustrated in FIG.
  • a corona shield 22 is provided at the end of the conductor 21, so as to prevent the electric discharge between the insulation surface along the inner wall of the receptacle and the grounded portion on the microscope body 9 side.
  • the insulator of the receptacle which intervenes between the primary coil and the secondary coil lies in a uniform electric zone owing to the conductive paints l6 and 21 which are respectively applied on the outer and inner surfaces of the receptacle.
  • the thickness of the insulator differs in dependence on the applied voltage. To take one example, it is about mm when an epoxy resin having a withstand voltage of IO kV/mm is used at an applied voltage of 100 kV. Considering the electrode shape and the safety factor, the thickness is determined upon the calculation of the electric field.
  • the secondary coil is mechanically mounted on the top part of the accelerating tube and is separated from the inner wall of the receptacle.
  • the merit of such structure is that the secondary coil whose output need be connected to the Wehnelt cylinder 6 and the filament 7 located within the accelerating tube can be directly joined by soldering, etc. If the secondary coil is mounted on the receptacle, a separable contact must be provided between the accelerating tube and the secondary coil. Accordingly, the structure of the top part of the accelerating tube becomes complicated, and troublesomeness is inevitably involved in the assembling job.
  • FIG. 4 shows another embodiment of this invention.
  • the same symbols as in FIG. 2 indicate the same constituent members.
  • three insulated transformers are provided.
  • An insulated transformer 24 feeds power to a driving motor 28, to perform the alignment of the filament 7 integral with the Wehnelt cylinder 6.
  • An insulated transformer 25 heats the filament 7.
  • the secondary coils of these two transformers are fixed at the top part of the accelerating tube 1, and are separated from a receptacle 32.
  • An insulated transformer 26 bestows a bias voltage between the filament and the Wehnelt cylinder through a smoothing circuit 27.
  • the secondary coil 18" is mounted on the receptacle 32 and supplies power to the smoothing circuit inside the acclerating tube by means of a contact 29 provided on the side wall of the top part of the accelerating tube.
  • At least one transformer whose insulator is a part of the receptacle made of an insulator is employed, so that the insulated control rod which is prone to creepage discharge is not required and that the alignment of the filament, the change-over of a plurality of filaments contained therein, etc., can be made by a motor, a relay or the like.
  • a continuously variable voltage can be supplied to the Wehnelt cylinder. The invention has such remarkable effects.
  • a charged particle accelerator including electron ray generating means having a Wehnelt cylinder provided in the vicinity of a filament in an accelerating tube and means for applying a bias voltage to said Wehnelt cylinder to adjust the amount of electron rays emitted from the filament,
  • the improvement comprising a receptacle surrounding said acclerating tube and made of an insulator, an outer grounded conductor layer provided on an outside surface of said receptacle, at least one transformer formed by a primary coil arranged on the outside of said receptacle and connected to said bias voltage means and a secondary coil arranged on the inside of the receptacle opposite said primary coil with the receptacle wall therebetween, and means connecting said secondary winding to said Wehnelt cylinder for rectifying the induced voltage of said secondary coil and applying said rectified voltage to said Wehnelt cylinder as said bias voltage, whereby a continuously variable bias voltage can be applied to said Wehnelt cylinder by regulating the voltage applied to said primary windmg.
  • the charged particle accelerator according to claim 1 further including an additional conductor layer 5 provided on an inside surface of said receptacle at the transformer forming portion, and means for shielding an end part of said additional conductor layer against corona.
  • the charged particle accelerator according to claim 1 further including means for establishing a constant field zone enclosing the portion of said receptacle contacting said outer conductor layer.
  • said means for establishing a constant field zone includes a second conductive layer disposed receptacle said receptable opposite said outer conductive layer.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Particle Accelerators (AREA)
  • Electron Sources, Ion Sources (AREA)
US484339A 1973-07-02 1974-06-28 Charged particle accelerator with integral transformer and shielding means Expired - Lifetime US3895254A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP48073699A JPS529971B2 (de) 1973-07-02 1973-07-02

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JP (1) JPS529971B2 (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4016499A (en) * 1975-07-17 1977-04-05 Gersh Itskovich Budker Charged particle accelerator
FR2552264A1 (fr) * 1983-09-17 1985-03-22 Leybold Heraeus Gmbh & Co Kg Canon electronique pour le chauffage de materiaux, en vue du soudage en particulier
US5118991A (en) * 1989-09-09 1992-06-02 Ptr Prazisionstechnik Gmbh Electron beam generator for an electron gun
US5235188A (en) * 1990-08-10 1993-08-10 U.S. Philips Corporation Charged particle beam device
US20120025106A1 (en) * 2009-04-14 2012-02-02 Manfred Apel Beam head
US20150179387A1 (en) * 2012-06-11 2015-06-25 Hitachi High-Technologies Corporation Charged particle beam generating apparatus, charged particle beam apparatus, high voltage generating apparatus, and high potential apparatus
US10694616B2 (en) * 2018-10-29 2020-06-23 Nuctech Company Limited Filament power supply for electron accelerator and electron accelerator

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5268918A (en) * 1975-12-05 1977-06-08 Hitachi Ltd Insulated transformer

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1815131A (en) * 1921-10-14 1931-07-21 Rca Corp Means for heating filaments
US3119931A (en) * 1960-06-28 1964-01-28 Philips Corp Circuit means for coupling an x-ray device to a control supply apparatus
US3283120A (en) * 1963-03-23 1966-11-01 United Aircraft Corp Apparatus for working materials with a beam of charged particles
US3288120A (en) * 1963-11-22 1966-11-29 Daimler Benz Ag Rotary piston internal combustion engine
US3808498A (en) * 1971-11-17 1974-04-30 Jeol Ltd Electron beam generating source

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1815131A (en) * 1921-10-14 1931-07-21 Rca Corp Means for heating filaments
US3119931A (en) * 1960-06-28 1964-01-28 Philips Corp Circuit means for coupling an x-ray device to a control supply apparatus
US3283120A (en) * 1963-03-23 1966-11-01 United Aircraft Corp Apparatus for working materials with a beam of charged particles
US3288120A (en) * 1963-11-22 1966-11-29 Daimler Benz Ag Rotary piston internal combustion engine
US3808498A (en) * 1971-11-17 1974-04-30 Jeol Ltd Electron beam generating source

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4016499A (en) * 1975-07-17 1977-04-05 Gersh Itskovich Budker Charged particle accelerator
FR2552264A1 (fr) * 1983-09-17 1985-03-22 Leybold Heraeus Gmbh & Co Kg Canon electronique pour le chauffage de materiaux, en vue du soudage en particulier
US5118991A (en) * 1989-09-09 1992-06-02 Ptr Prazisionstechnik Gmbh Electron beam generator for an electron gun
US5235188A (en) * 1990-08-10 1993-08-10 U.S. Philips Corporation Charged particle beam device
US20120025106A1 (en) * 2009-04-14 2012-02-02 Manfred Apel Beam head
CN102396035A (zh) * 2009-04-14 2012-03-28 西门子公司 射束头
CN102396035B (zh) * 2009-04-14 2014-08-27 西门子公司 射束头
US8946657B2 (en) * 2009-04-14 2015-02-03 Siemens Aktiengesellschaft Beam head
US20150179387A1 (en) * 2012-06-11 2015-06-25 Hitachi High-Technologies Corporation Charged particle beam generating apparatus, charged particle beam apparatus, high voltage generating apparatus, and high potential apparatus
US9548182B2 (en) * 2012-06-11 2017-01-17 Hitachi High-Technologies Corporation Charged particle beam generating apparatus, charged particle beam apparatus, high voltage generating apparatus, and high potential apparatus
US10694616B2 (en) * 2018-10-29 2020-06-23 Nuctech Company Limited Filament power supply for electron accelerator and electron accelerator

Also Published As

Publication number Publication date
JPS529971B2 (de) 1977-03-19
JPS5023767A (de) 1975-03-14

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