CN1395459A - Method for utilizing radio-frequency to accelerate electrons - Google Patents

Abstract

The method for speeding up electronic includes following steps. In the betatron, the guiding of the electron orbit is setup by the four blocks of the separated magnets. The snakelike sizing block for correcting the field is added to each side of the magnet. The four blocks of the separated magnets meet the following condition; the sum of the deflection angles of the magnet beam flow is 360 degree; the perimeter of the center orbit is the integral multiple of the radio frequency wavelength of the speeding voltage. The accelerating chains of the radio frequency single cavity speed up electrons longitudinally and respeatedly, making electrons do circumnutation about 5-10 cycles. In the acceleration process, the accelerating phases are slid within plus or minus 60 degrees.

Description

Utilize the method for radio-frequency to accelerate electrons

Technical field:

The present invention relates to accelerator art, specifically a kind of method of utilizing radio-frequency to accelerate electrons.

Background technology:

Microtron (MICROTRON) is the very strong competitor of electron linear accelerator as a kind of irradiation bomb.But because the orbit correction difficulty is unsuitable for producing in batches.The racetrack microtron that Hou is succeeded in developing changes microwave single resonance chamber the accelerating tube of one section electron linear accelerator into, and will dominate magnet and be divided into two, has reserved the drift section of electron orbit, and the orbit correction situation is slightly taken a favorable turn.Yet cost also increases considerably thereupon, has weakened competitive advantage.Someone imagines electron orbit is further separated, magnet is divided into a lot of pieces, put by petal, and adopt the radio-frequency (RF) coaxial chamber laterally to quicken, and reduced cost, made things convenient for and transferred bundle, this kind accelerator is called as RHODOTRON, mean ' rosette accelerator ', but its complex structure, acceleration efficiency is low.

Summary of the invention:

The objective of the invention is a kind of method of utilizing radio-frequency to accelerate electrons of designing at the deficiencies in the prior art, this kind method is used in the electron accelerator, it has the advantage of racetrack microtron and rosette accelerator concurrently, and in technical pattern, the acceleration principle aspect then is very different, be more economically a kind of, the irradiation accelerator of being more convenient for promoting is expected to become a kind of suitable device in the irradiation technique field.

Utilize the method for radio-frequency to accelerate electrons, it may further comprise the steps:

A, in microtron, with magnet M1, M2, M3, the M4 of four separation the guiding of electron orbit is set, every magnet side is added with the snakelike parallels that alignment field is used, and the setting of four discrete magnets is met the following conditions:

I, magnet M1, M2, M3, M4 beam bending angle sum are 360 °;

The girth of the central orbit of ii, electron cyclotron motion is the integral multiple of accelerating voltage radio frequency wavelength;

B, with the vertical accelerated electron of radio frequency list chamber acclerating section, and repeat repeatedly to carry out, make electronics do circumnutation, in electron cyclotron 5-10 week, in accelerator, accelerating phase slides in ± 60 °.

The present invention can be applicable to a lot of aspects as irradiation technique:

(1) sterilization, mildew-resistant, desinsection, sterilization

Grain, vegetables, the mildew-resistant of fruit, insect protected;

Melon and fruit fresh-keeping;

Packed food anticorrosion;

Milk, the sterilization of beverage;

The sterilization of books, retaining case, anti-mould and anti-moth.

(2) sterilization of health care

The sterilization of medicinal material;

The sterilization of medicine equipment.

(3) commercial Application

Radiation modification, irradiation damage;

High molecular radiation crosslinking;

Flaw detection.

(4) research application

Radioactive breeding.

The accelerator that adopts the present invention to obtain has following characteristics:

(1) production cost is low.Used radio frequency is in the radio and television frequency range, and transmitter is easy to obtain domestic industry support.Radio-frequency range cavity and transmitter processing cost are also low than microwave equipment.Do not need heavy duty machine tools equipment and special process in the whole course of processing.With existing other kind electron accelerator ratio,, have a clear superiority in from the production angle.

(2) transfer Shu Rongyi, be suitable for producing in batches.

Move (3), safeguard that simply general dynamo-electric personnel just can be competent at, help promoting.

(4) small investment, the duration is short, needs several and does several, does not need large-scale factory building place.

Description of drawings:

Fig. 1 for electronics among the present invention at accelerator phase change schematic diagram

Fig. 2 is the accelerator general structure schematic diagram among the present invention

Consult Fig. 1,2, adopt 100-300 megahertz High-frequency machine, lotus root is bonded to coaxial cavity and vertically accelerates. Rail-guided magnet is divided into four. Acceleration orbit becomes track type, can carry out the school to track in the drift region Just. The separation of deflecting region magnet is for the injection of electron beam provides the space. Electron gun use etc. from The daughter negative electrode is to improve the life-span. Because the radio frequency wavelength is longer, electronics is the theory of relativity in accelerator It is an a small amount of that the track length variation that the growth of character amount causes is compared with route track length, whole adding Accelerating phase slides in the positive area in the speed process, and wants unlike the conditional electronic cyclotron Ask electron mass to increase by integral multiple, thereby accelerator can become track and accelerate, can change easily Become the energy of educt beaming flow. Accelerating cavity voltage can be adjusted magnetic field between 500 kilovar to 2 megavolts Also correspondingly adjust between thousands of Gausses from hundreds of. As long as accelerating phase does not skid off the positive area, can Accelerate with the orbit determination road, also can adopt not orbit determination speed technology, accelerator has very big flexibility.

Consult Fig. 2, electron gun EG provides the electronic beam current of 50,000 electron volts, injects the radio frequency accelerating cavity RF.K accelerates Hou, through leading magnet M1, M2, M3, M4 deflection, again enters cavity and accelerates, and is straight Draw to reaching predetermined power Hou. BM can draw for electron beam irradiation for drawing electronic beam current Use, the generation X ray of also can practicing shooting is used for x ray irradiation x. Cavity is encouraged by a High-frequency machine, High-frequency machine is determined by different type of machines that with high-power ceramic pipe self-oscillation, concrete power efficient can reach 80%, can be from 10,000 watts to apolegamy thousand watt of the hundreds of. High-frequency machine may be worker under the pulse condition Do, need join the pulse power. Whole accelerator is worked under high vacuum state, and vavuum pump is installed Below the drift section of M1, M2 and M3, M4.

Basic thought of the present invention is to accelerate with the microwave that radio frequency list chamber replaces in the microtron The chamber, thus the microwave system of costliness is changed to cheap radio system, reduced the manufacturing of accelerator Cost has kept simultaneously racetrack microtron track and has been easy to proofread and correct, compact conformation excellent The point. We are called it in ' radio frequency electric cyclotron ', English called after ' RADIO FREQUENCE ELECTRON CYCLOTRON ' is abbreviated as ' RFEC ', and Chinese is called for short ' radio frequency electric '. Every kGy The investment of irradiation yield equipment needed thereby is much smaller than other type.

Embodiment:

With 120,000 watts of medium size installations, RFEC-120 is an example, and its design parameter is as follows:

Electron energy 12MeV (just being adjusted to 6MeV);

Flow strong 10mA (just being adjusted to 5mA);

Beam power 120kW (just being adjusted to 30kW);

Ray conversion efficiency (tungsten target) is total 30%, leading peak 19%. (initial adjustment total 19%, leading peak 11%);

Output power 200kW.

RFEC-120 is by electron gun, the high frequency accelerating system, and three most compositions of magnet, auxiliary system has vacuum system and automatic control system, regular service equipment such as power supply water-cooled.Electron gun requires axially to draw and becomes the circle bundle, does not have what difference with the specification requirement of most of electron beam equipments, and this technology is ripe in China, only need apply mechanically a kind of standard design and get final product.The energy of drawing of electron beam is 50 kilovars, and stream is tens of milliamperes by force, is the secondary technology level at home.Single chamber acclerating section similar design in accelerating cavity employing and the single chamber accelerator, domestic existing technology for full deposit.Inductothermy apparatus and high power television transmitter require identical, and inductothermy apparatus can adopt homemade earthenware, stable performance, and price is wanted considerably cheaper than imported goods.Total specification requirement is: hunting power reaches 150,000 watts, and acceleration efficiency is 0.8.Power consumption is 200,000 watts, and the high frequency transformation efficiency is 0.75.Accelerator gross efficiency about 60%.Quickening slit voltage is 2 megavolts.Specific practice is: the guiding of electron orbit is set, four symmetrical in twos compositions of magnet in the high frequency accelerating system.Its design parameter is as follows:

4 centimetres of magnetic pole gaps;

Magnetic field intensity 0.2 tesla;

Excitatory ampere-turn 1 * 10 ⁴Ampere-turn.

And to make it satisfy four magnet beam bending angle sums be 360 °, and every block of magnet all makes 90 ° of track deflections, and putting of four blocks of magnet will be satisfied: the central orbit girth of electron cyclotron motion is the integral multiple (present embodiment is 3 times) of accelerating voltage radio frequency wavelength.Every magnet side all is added with the snakelike parallels that alignment field shape is used, and uses the vertical accelerated electron of radio frequency (200kHz) single chamber acclerating section then, and this acceleration repeats repeatedly to carry out, and accelerating phase slides in ± 60 ° of phase regions in the accelerator.Rollback point is set in electronics and crosses over central orbit and gets over when quickening the slit, and that time in the middle of just in the electron cyclotron process or twice be crack (is that odd number still is that even number is decided on the number of times that always circles round) more, and present embodiment is got over the crack 6 times.Along with the growth of electron energy, the also corresponding increase of the quality of electronics.Condition of resonance between rf frequency and the electronics gyrofrequency can not accurately satisfy, and realizes omnidistance the acceleration by the reasonable phase shift allocations in the positive area.More the crack is 6 times, and accelerating phase is respectively :+20 ° 0 °, and-20 °-20 ° 0 °, among+20 ° of Fig. 1 shown in 1,2,3,4,5,6 each points.

Consider the edge effect of magnet, the corner is revised during design.Model machine adds benefit iron in the corner, so that field shape is accurately revised.During orbit correction, can add some plate coils, each bar track is proofreaied and correct respectively in deflecting magnet yoke portion.Because magnetic field numerical value is lower, a shape is discrete less, so by changing the numerical value of magnetic field intensity and high frequency voltage, just can change the energy of line.

Magnet system adopt to be separated the polylith structure, does that like this orbit correction is become easily, also makes the magnet miniaturization, is convenient to processing, makes the total cost reduction.Magnet separates Hou, the designs simplification of vacuum chamber, and load performance takes a turn for the better, the also corresponding attenuating of processing cost.The layout of magnet, mainly consider the needs of the requirement and the track levelling of beam dynamics, each bar orbital drift Duan Shangke correction up coil, in order to improve beam transport efficient, because radio frequency list chamber lateral dimension is bigger, the deflecting magnet at two ends is divided into two by 45 degree, and the centre is drawn back, and also injecting to electronics provides the space.

It is 5 * 10 that vacuum degree requires ^-6Holder can be selected two of homemade 1500 liters of/second oil diffusion pumps for use, is installed in the magnet left and right sides respectively.

Robot control system(RCS) is implemented by a PC industrial computer, except that accelerator is operated, also irradiation system is monitored.

Electron beam is drawn Hou, adds one scan magnet, and the direct irradiation object of available electron bundle also can be adorned a heavy metal target, produces X ray in order to irradiation.This will be the accelerator auxiliary equipment according to user's Demand Design.

Claims (1)

1, a kind of method of utilizing radio-frequency to accelerate electrons is characterized in that it may further comprise the steps:

A, in microtron, with magnet M1, M2, M3, the M4 of four separation the guiding of electron orbit is set, every magnet side is added with the snakelike parallels that alignment field is used, and the setting of four discrete magnets is met the following conditions:

I, magnet M1, M2, M3, M4 beam bending angle sum are 360 °;

The girth of the central orbit of ii, electron cyclotron motion is the integral multiple of accelerating voltage radio frequency wavelength;

B, with the vertical accelerated electron of radio frequency list chamber acclerating section, and repeat repeatedly to carry out, make electronics do circumnutation, in electron cyclotron 5-10 week, in accelerator, accelerating phase slides in ± 60 °.