Electric lamp and discharge devices: systems – Current and/or voltage regulation – Automatic regulation
Patent
1981-08-05
1983-08-09
La Roche, Eugene R.
Electric lamp and discharge devices: systems
Current and/or voltage regulation
Automatic regulation
315 10, 315101, 315106, H05B 7148
Patent
active
043981321
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to accelerator technique, and more particularly to electron beam current stabilizing devices.
BACKGROUND OF THE INVENTION
It is known that the magnitude of a charged particle beam current in the accelerators designed for industrial application is a basic factor defining the radiation dose value within the accelerator irradiation field. When the material is treated by a charged particle beam, for example, by an electron beam, it acquires certain predetermined properties depending on the radiation dose. Unstability of the radiation dose results in deviation and spread of the properties of the irradiated material from the predetermined specifications. In order to provide the stability of the radiation dose it is very important to stabilize the electron beam current.
The magnitude of the electron beam current is adjusted generally by alteration of the cathode emission current varying either the cathode heater current or the intensity of the electric field around the cathode of the accelerating tube.
Known in the art is an electron beam current stabilizing device (Cf. an article by Akoulov V. V. et al. "Promishlennie uskoriteli serii "Elektron" dlja radiatsionnoi himii", preprint of NIIEFA No. D-0198, Leningrad, 1974, p.II), comprising a ferroresonant voltage regulator connected to a secondary winding of an accelerator high-voltage transformer, designed to supply the accelerating tube cathode heater, and an adjustable autotransformer connected to the output of the ferroresonant regulator. Connected to the output of the autotransformer is a primary winding of the cathode heater transformer, the autotransformer being regulated by means of a reversible electric motor the shaft of which is coupled through an insulating bar with a sliding contact of the autotransformer. The reversible motor is actuated by an operator controlling the magnitude of the electron beam current.
The aforementioned device provides considerably low beam current stability because of, in the first place, low stability of ferroresonant voltage regulators when alteration of the voltage in a supply network occurs, in the second place, the ambiquous relation between the cathode heater voltage and the cathode temperature (the resistance of the heater circuit and herewith the heater current may vary in the course of operation resulting in the alteration of the cathode temperature which brings, in its turn, again to the alteration of the heater circuit resistance etc.) whereas it is known that the cathode emission current depends exactly on the cathode temperature and, in the third place, the loss of emissive properties by the activated cathode due to the aging of said cathode.
Besides, the aforementioned device fails to provide automatic adjustment of the beam current and therefore a considerably large period of time may pass from the moment of alteration of the beam current to the moment of effecting the control, during which the radiation dose will not correspond to a rated value thus leaving a part of the treated material devoid of the required property.
Known in the art is an electron beam current stabilizing device (C.f. Japanese Pat. No. 34514, published in 1974), comprising a thyristor current stabilizer inserted in the cathode heater circuit. The beam current is adjusted in this device, similar to the aforementioned one, by an operator actuating the current stabilizer through insulating bar coupled with the shaft of the reversible electric motor. The device according to this patent provides better stability of the beam current since the heater current and not the heater voltage define the temperature of the cathode and consequenty the beam current. However, the stability of the beam current is still not sufficient due to participation of a man in the process of control.
Also known in the art is an electron beam current stabilizing device (Cf. U.S. Pat. No. 3,293,483 published in 1966), comprising a photosensitive element connected to a cathode of an accelerating tube to adjust the beam
REFERENCES:
patent: 3293483 (1966-12-01), Engel
patent: 3611017 (1971-10-01), Freeland
patent: 3909662 (1975-09-01), Thomas et al.
Translation of Russian Publication entitled "Beam Control Unit for Charged Particle Accelerator".
Akulov et al., "Industrial Accelerators of Electron Type for Radiative Chemistry", Preprint D-0198, L., SRIEA, 1974, 18p., with ill.
Dmitriev Stanislav P.
Razin Gennady I.
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