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US3268758A - Hollow gas arc discharge device utilizing an off-center cathode - Google Patents

Hollow gas arc discharge device utilizing an off-center cathode Download PDF

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Publication number
US3268758A
US3268758A US367266A US36726664A US3268758A US 3268758 A US3268758 A US 3268758A US 367266 A US367266 A US 367266A US 36726664 A US36726664 A US 36726664A US 3268758 A US3268758 A US 3268758A
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United States
Prior art keywords
cathode
hollow
chamber
discharge
anode
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Expired - Lifetime
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US367266A
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English (en)
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John W Flowers
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Individual
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Priority to US367266A priority Critical patent/US3268758A/en
Priority to GB11663/65A priority patent/GB1061453A/en
Priority to DEU11711A priority patent/DE1240199B/de
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Publication of US3268758A publication Critical patent/US3268758A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T1/00—Details of spark gaps
    • 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
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/32532—Electrodes
    • H01J37/32596—Hollow cathodes
    • 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
    • H05H1/48—Generating plasma using an arc
    • H05H1/50—Generating plasma using an arc and using applied magnetic fields, e.g. for focusing or rotating the arc

Definitions

  • the second method of operation in the above patent utilized a PIG-type discharge.
  • a pair of hollow cathodes were aligned along the magnetic field with an aligned coaxial hollow anode interspersed therebetween and gas was fed to both cathodes.
  • Arcs of this type have been run at about 100 amperes and a voltage of about 1000 volts with other parameters being about the same as those for the arc discharge in the first method described above.
  • FIG. 1 is a cross-sectional view of one embodiment of the present invention for producing a hollow arc discharge
  • FIG. 2 is a cross-sectional view of a second embodiment for producing a hollow discharge
  • FIG. 3 is a graph showing the measured relationship between arc voltage and current for various operating conditions for the device of FIG. 1 or FIG. 2.
  • the above objects have been accomplished in the present invention by providing a self-heated cathode or 3,268,758 Patented August 23, 1966 cathodes disposed and mounted off-center of the axis of the discharge chamber and of an axial magnetic field.
  • a refluxing-type discharge is established with this cathode or cathodes, and a surrounding cylindrical anode provides a sufliciently large radial component of electric field so that there is a large rotational drift of the discharge to produce a hollow discharge symmetrical about the axis of the anode.
  • the size of the hollow discharge thus produced is determined by the distance that the cathode is mounted from the axis of the anode.
  • a cylindrical vacuum chamber 1 is provided with externally projecting end flanges 2, 2'.
  • One end of chamber 1 is closed with a cathode mounting block 3 which, in turn, is separated from flange 2 with a pair of hollow cylindrical insulators 4, 5.
  • an annular radial disc-shaped shield 6 Interposed between these insulators is an annular radial disc-shaped shield 6.
  • the structure of the anticathode or reflector end of the chamber 1 is similar, with the reflector being a block 7 spaced from flange 2' by two insulators 8, 9.
  • a second radial shield 10 is held between the insulators 8, 9.
  • Within the chamber 1 is mounted an annular anode 11 spaced about equally between flanges 2, 2'.
  • At least one small hollow cathode 12 is mounted perpendicular to the cathode mounting block 3 so that the axis thereof is parallel to, but not on, the axis of the chamber 1.
  • the position of the cathode is at a smaller radius in the chamber 1 than is the inner surface of the anode 11 or the inner diameters of the shields 6, 10.
  • the dimensions of the radius of the inner surface of the anode 11 and the inner diameters of the shields 6, 10 as shown in FIG. 1 are by way of example only. These dimensions may be made larger than those shown in FIG. 1, if desired, and the cathode 12 can thus be placed at a larger radius to thereby increase the diameter of the hollow discharge to be provided by this device.
  • the cathode mounting block 3, reflector block 7, and the chamber 1 are provided with cooling means such as tubing 13 through which water or other coolant is caused to flow.
  • the chamber 1 is evacuated by means of a vacuum pump 14 which is in communication with the chamber by means of a conduit 15, and annular magnetic field coils 24 are provided to produce an axial magnetic field within the chamber 1 in a conventional manner.
  • a gas supply 16 is provided to supply feed gas such as argon or hydrogen, for example, to the cathode 12 through a feed tube 17.
  • a source of electrical power 18 is provided to impress, through leads 19, 20, the proper voltage to the anode 11 and cathode 12.
  • the reflector 7 is normally permitted to electrically float.
  • the chamber 1 may be provided with a port through which ions, neutrals, etc., may be injected for reaction with the hollow discharge.
  • the cathode mounting block 3 is provided with an aperture 21 for injecting ions, electrons, etc., axially into the hollow discharge.
  • an aperture 22 is provided in the reflector block 7 to permit axial withdrawal of ions, etc., from the hollow discharge.
  • the aperture 22 may be lined with an insert 23 to withstand the heat generated by the passage therethrough of the ions, etc. Because of the manner of operation of this embodiment, it would be operated within a separate vacuum chamber; therefore, no means for producing a vacuum are shown.
  • FIG. 1 or FIG. 2 of the present invention The operation of either FIG. 1 or FIG. 2 of the present invention is essentially the same.
  • the chamber 1 is evacuated to a pressure of about 5 10 Torr, and the magnetic field adjusted to be of the order of 6000 gauss at the cathode 12.
  • a DC. potential of about 300 volts is applied between the cathode 12 and anode 11, and as gas is admitted through the cathode, an arc discharge is struck using, for example, a short burst of RF signal superimposed upon the DC. voltage.
  • the radial component of electric field introduced by the annular anode causes a rotational drift in the discharge so as to create a hollow discharge symmetrical about the axis of the chamber 1 having a radius equal to the distance the cathode is spaced from the axis.
  • This radius of the hollow arc discharge may be adjusted, if desired, and this could be accomplished by providing means, not shown, for adjusting the radial position of the cathode 12 with respect to the axis of the chamber 1.
  • one cathode about A; inch in diameter and located about inch off the axis of the chamber produced a discharge about inch in diameter.
  • the intensity of the discharge was then controllable by regulating the gas feed to the cathode and/ or by adjustment of the potential applied between the cathode and anode.
  • the relationship between discharge current and applied voltage for several feed gases is shown in FIG. 3.
  • the resultant discharges were very stable even at the low voltage utilized, compared to 1000 volts for the PIG-type arc discharge in the aforementioned Patent No. 2,927,232.
  • gas utilization in the present invention is more eflicient than in the above prior patent, which is evidenced by the low pressure in the present device.
  • the embodiment of the present invention as shown in FIG. 2 may be used as an ion source for a 100 kw. accelerator of the type shown in FIG. 3 of US. Patent No. 3,075,115, issued January 22, 1963.
  • a relatively small, hollow reflux-type arc discharge was provided and a stream of high-energy electrons were caused to axially penetrate the discharge so as to provide the necessary electrons for space-charge neutralization of the ion beam being withdrawn from the ion source.
  • the output of such an accelerator is relatively poor and not very eflicient due to poor gas utilization and the requirement of about 1500 volts for stable operation of the arc discharge. Since the refluxtype are discharge of FIG.
  • Means for establishing a hollow cylindrical arc discharge comprising an elongated evacuated chamber, a hollow cathode mounted in one end of said chamber, a reflector electrode mounted within the other end of said chamber, an elongated, hollow anode positioned within said chamber between said cathode and said reflector electrode to provide a radial electric field component therewithin, said chamber and anode having a common axis, a source of feed gas, means for feeding gas from said source into the interior of said cathode at a controlled nate, means for providing a magnetic field parallel to said common axis, a source of operating potential connected between said anode and cathode, said cathode being mounted a selected distance from said common axis such that the axis of said cathode is spaced from and parallel to said common axis to establish an offcenter refluxing arc discharge parallel to said magnetic field and between said cathode and said reflector electrode, said discharge being caused to rotationally drift by said radial component of
  • each of said mounting block and said reflector electrode is provided with an axially disposed aperture, whereby high energy electrons may be axially injected into said hollow discharge through said mounting block aperture and a space-charged neutralized beam of electrons and ions may be withdrawn from said chamber through said reflector electrode aperture.
  • feed gas is selected from a group of gases including argon and hydrogen.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electron Sources, Ion Sources (AREA)
US367266A 1964-05-13 1964-05-13 Hollow gas arc discharge device utilizing an off-center cathode Expired - Lifetime US3268758A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US367266A US3268758A (en) 1964-05-13 1964-05-13 Hollow gas arc discharge device utilizing an off-center cathode
GB11663/65A GB1061453A (en) 1964-05-13 1965-03-19 Hollow gas arc discharge
DEU11711A DE1240199B (de) 1964-05-13 1965-05-11 Entladungsvorrichtung zum Erzeugen einer energiereichen Bogenentladung

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US367266A US3268758A (en) 1964-05-13 1964-05-13 Hollow gas arc discharge device utilizing an off-center cathode

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US3268758A true US3268758A (en) 1966-08-23

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US (1) US3268758A (de)
DE (1) DE1240199B (de)
GB (1) GB1061453A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3326769A (en) * 1966-07-20 1967-06-20 Rodger V Neidigh Energetic electron plasma blanket
US3363130A (en) * 1965-10-23 1968-01-09 Atomic Energy Commission Usa Frequency tuning of an energetic arc discharge by varying the diameter of the cylindrical hollow arc
US4084076A (en) * 1977-05-10 1978-04-11 Evgeny Ivanovich Istomin Electron beam welding gun

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2312709A (en) * 1996-04-30 1997-11-05 David Johnston Burns Flying craft with magnetic field/electric arc vertical thrust producing means
EP1640608B1 (de) * 2004-09-22 2010-01-06 Elwing LLC Antriebssystem für Raumfahrzeuge

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2831996A (en) * 1956-09-19 1958-04-22 Eugene F Martina Ion source
US2969308A (en) * 1958-08-07 1961-01-24 Persa R Bell Method of producing energetic plasma for neutron production
US3116433A (en) * 1959-06-15 1963-12-31 Giannini Controls Corp Production of neutral molecular beams

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2831996A (en) * 1956-09-19 1958-04-22 Eugene F Martina Ion source
US2969308A (en) * 1958-08-07 1961-01-24 Persa R Bell Method of producing energetic plasma for neutron production
US3116433A (en) * 1959-06-15 1963-12-31 Giannini Controls Corp Production of neutral molecular beams

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3363130A (en) * 1965-10-23 1968-01-09 Atomic Energy Commission Usa Frequency tuning of an energetic arc discharge by varying the diameter of the cylindrical hollow arc
US3326769A (en) * 1966-07-20 1967-06-20 Rodger V Neidigh Energetic electron plasma blanket
US4084076A (en) * 1977-05-10 1978-04-11 Evgeny Ivanovich Istomin Electron beam welding gun

Also Published As

Publication number Publication date
DE1240199B (de) 1967-05-11
GB1061453A (en) 1967-03-15

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