A synchrotron construction the magnetic field of which is without steel core is suggested. Acceleration chamber is combined with magnetizing winding. The described version of accelerator is favorably different in small weight, simplified production and assembling technique

Moskalev, Vladilen Aleksandrovich

Electronic archive of Tomsk Polytechnic University

ent part in beam capture. The values of charge limitaccumulated at the injection (7·1010 el.) and captured at the acceleration (4·1010 el.) are obtained.4. Possible increase in capture efficiency by means ofvariation of external magnetic field and beam energy selection of circuital decelerating EMF is investigated. Thus, at the electron energy 40 keV and theenergy selection value 200 eV/rev, capture efficiencyincreases by the factor of 1,5, which permits thecapture at the acceleration 6·1010 el. The maximumcapture parameters are obtained at combination ofvariation of the external magnetic field and decelerating EMF: Ncap≈7,4·1010 el., Kcap≈7,4 %.Bulletin of the Томsк Pоlytеchnic University. 2007. V. 310. № 164REFERENCES1. Vorobyev А.А., Kononov B.А., Evstigneev V.V. Betatron electronbeams. – Moscow: Atomizdat, 1974. – 152 p.2. Moskalev V.А. Betatrons. – Moscow: Energoizdat, 1981. – 282 p.3. Matveev А.N. On the mechanism of capture and limit current in betatrons // Journal of Experimental and Theoretical Physics. – 1958.– V. 35. – № 2. – P. 372–380.4. Kovrizhnykh L.М., Lebedev А.N. Consideration of electron common interaction in cyclic accelerators // Journal of Experimentaland Theoretical Physics. – 1958. – V. 34. – № 4. – P. 984–992.5. Antoshkin М.Yu., Grigoriev V.P., Koval Т.V., Sablin N.I. Numericalmodel for investigation of axialasymmetrical wave excitation in coaxial vircators // Radio Technology and Electronics. – 1995. – № 8.– P. 1300–1305.6. Hokney R., Eastwood J. Numerical simulation by the particlemethod. – Moscow: Mir, 1987. – 640 p.7. Bruk G. Cyclic accelerators of charged particles. – Moscow: Atomizdat, 1970. – 311 p.8. Ofitserov V.V. Numerical simulation of nonstationary processes incyclic induction accelerators // Computer Techniques. – 2003. –V. 8. – № 6. – P. 322–330.9. Kasyanov V.А., Shtein М.М., Chakhlov V.L. Formation of focusingpoint of smallsize deceleration radiation // Devices and Techniqueof Experiment. – 1998. – № 1. – P. 41–42.Arrived on 11.10.2006Resonance electron accelerator – synchrotron withweak focusing of electron beam presents a complexelectricalphysical device consisting of a number of large units and their supply systems. The basic element ofsynchrotron is an electric magnet producing progressivemagnet field necessary for motion of charged electronsalong the orbit of constant radius. It is the so called«control magnet field». Synchrotron magnetic conductor is made of sheet transformer steel and requires highaccuracy of electromagnet assembling and mountingmade up of four sectors including azimuth angle 90°each. In general this system is the most labourconsuming, technologically complex and expensive part ofthe accelerator. Thus, the steel weight of the synchrotron «Sirius» electromagnet per 1,5 GeV in Tomsk Polytechnic University is 120 tons [1, 2].Control magnet field in the suggested synchrotronconstruction is induced by singleturn winding enclosing an azimuth circle quarter [3].The winding presents two concentrically locatedstrips of conductive material. The strips are connectedwith each other at one end, but at the other one they areconnected with alternating power supply. Current flowsin both strips in the opposite directions.In the space between the strips magnet field providing the motion of accelerated particles along the orbit(control synchrotron field) is produced. This field is topossess the property of electron beam axial focusing.In accelerator with «steel» magnet system focusing isachieved by shaping magnet field in «barrellike» formby means of increasing the gap between the electromagnet poles as it moves away from the system centre.To shape magnet field in a necessary form inducedbetween the poles of singleturn winding these poles areto bend in the vertical direction so that the convex part ofthe strip would present outside from the system centre.One more labourconsuming element of synchrotron is a vacuum acceleration chamber. It is glued froma large number of ceramic curved sectors forming anarch of quarter circle length, the radius of which corresponds to that of path curve of the accelerated electronbeam. Four of such arched sections connected withUDC 621.364.634.3IRONFREE ELECTRON SYNCHROTRON WITH WEAK FOCUSINGV.А. MoskalevTomsk Polytechnic UniversityEmail: mva@tpu.ruA synchrotron construction the magnetic field of which is without steel core is suggested. Acceleration chamber is combined with magnetizing winding. The described version of accelerator is favorably different in small weight, simplified production and assembling technique.each other by straight line sections (without magnet field) form a close circle of racetrack type placed in specific air gap of synchrotron electromagnet.Singleturn magnetizing winding includes circlespace by its turnings – strips, where the motion of accelerated electron beam is to take place. Overlapping theupper and lower winding turns by vacuumtight dielectric covers makes it possible to use the winding as an accelerating chamber.The scheme of the suggested synchrotron is presented in the figure. Singleturn magnetizing winding forinduction of control magnet field consisting of four similar sections – 1, is placed in circular sections of accelerated particle path, each of which is performed in theform of concentrically located circle parts made of copper strips – 2, 3 connected electrically at one end, but atthe other one connected to opposite poles of pulsepower supply – 4. The strips – 2, 3 are connected witheach other by dielectric vacuum seal along the edges 5and form the four sections of the accelerating chamber.The chamber sections are connected with each other bystraight vacuum electron wires – 6, and forms a closedaccelerating chamber of «racetrack» type. To providethe focusing properties of control magnet field («barrellike» form of the field force lines), conductive strips – 2,3 are bent in width with convexity outside from the accelerator centre, fig. 1, а). The synchrotron contains also an injector – 7, accelerating resonator or resonators– 8, vacuum pumps – 9, placed in the area of straightparts of the accelerated particle path.Application of singleturn winding for producingcontrol magnet field and simultaneously forming accelerating chamber permitsing refuse completely from steel magnetic conductor, lightens the accelerator severaltimes and simplifies its construction, provides free access to the accelerating chamber along its whole length,simplifies the accelerator production and assemblingtechnology and increases synchrotron serviceability.At the given connection of singleturn winding current flows in the opposite directions in both strips. As aMathematics and mechanics. Physics65Figure. Synchrotron scheme112 6438AA4676946114A – A a)5result in the space between the strips there is alternating,dying away magnet field along the radius. The stripsconvexity in width gives the field force lines a «barrellike» form typical for the focusing («betatron») field.All four sections of the singleturn winding form asynchrotron single magnet system. Sections of the singleturn winding connected with vacuum seals – 5along the strip edges – 2, 3 form four curvilinear sections of accelerating chamber combined with magnetizing singleturn winding.These curvilinear sections are connected with eachother by straight electron wires and form a closed chamber as it is done in the known synchrotrons of «racetrack» type. The straight sections of the acceleratingchamber free from magnet field are used to assemble theattendant equipment – resonators, vacuum pumps etc.The value of control magnet field strength in the accelerator orbit depends on energy of the acceleratedparticles; the maximum field strength is determined bysetting value of particle energy that is desired to obtain.Injection of the charged particles into acceleratingchamber is made by the injector – 7, particle acceleration – by means of resonator or resonators – 8, vacuumin the chamber is provided by the pumps – 9.Thus, the use of singleturn winding concept for induction of control magnet field (similar to singleturnwinding used in miniature induction cyclic accelerator[4]) in the form of four similar sections located in circular sectors of the accelerated particle path, at simultaneous performing of the winding the function of accelerating chamber results in creation of charged particleaccelerator of new type, i.e. ironfree synchrotron having a number of new technical and engineeringeconomical parameters, such as small weight of the acceleratorand the accelerating chamber, combination of magnetizing winding and accelerating chamber functions in asingle system, simplified technology of the acceleratorproduction and assembling and etc. Therefore, the suggested ironfree synchrotron is favourably distinguishedfrom all the known accelerators of such type.Bulletin of the Томsк Pоlytеchnic University. 2007. V. 310. № 166REFERENCE1. Electron synchrotron «Sirius» // Formation and Development ofScientific Schools in Tomsk Polytechnic University / Edited byYu.P. Pokholkov, V.Ya. Ushakov. – Tomsk, 1996. – P. 158–160.2. Vorobyev А.А., Chuchalin I.P., Vlasov А.G. et al. TPI Synchrotronper 1,5 GeV. – Moscow: Atomizdat, 1968. – 160 p.3. Pat. 2265974 RF. IPC H05H 13/04. Ironfree synchrotron /V.А. Moskalev. Published 10.02.2005, Bull. № 34.4. Pat. 2193829 RF. IPC H05H 11/00. Induction charged particle accelerator / V.А. Moskalev. Published 27.11.2002, Bull. № 33.Arrived on 21.04.2006IntroductionThe application of pulsed electron beam for the initiation of plasmachemical processes, gas laser injection,microwave radiation generation and other fields requiresthe development of efficient electron accelerator whichwould possess long operation life time and high stability ofoperation parameters. Any nonproductive energy losseslead to the heating and premature destruction of construction units of the accelerator. The experimental investigations performed by us and the analysis of work of otherauthors [1, 2] showed that the accelerator operation life time is mainly determined by the diode unit.The presence of nonproductive losses in the diodeunit can be calculated by the current balance. The totalcurrent introduced to the diode unit from the nanosecond generator is equal to the sum of extracted electron beam current, current of capacity charge exchangeof the diode unit and parasite losses current. The lossesduring the electron beam generation can be conditioned either by the electron beam scattering while goingfrom the cathode to the Faraday cup collector or by thecharge escape along the isolator surface, or by the parasite discharges in the vacuum volume of the diodechamber. One of the principal loss sources in the diodeUDC 621.384.647RESEARCH OF CHARGE BALANCE IN DIODE UNIT OF PULSED ELECTRON ACCELERATOR A.I. Pushkarev, R.V. SazonovHigh Voltage Research Institute, TomskEmail: aipush@mail.ruThe results of experimental research of charge balance in the diode unit of highcurrent pulsed electron accelerator TEU500 (350...500keV, 60 ns, 250 J per pulse) at the operation of electron beam generation are presented. The investigations are performed for the planar diode as with the cathodes made of graphite, copper, carbon fiber 43...60 mm in diameter so with the multiedge cathode. It isshown that the main source of parasite losses of electrons in the planar diode is their scattering in the anodecathode gap induced bythe electron field distortion at the cathode periphery. In the matching mode of diode impedance to the output resistance of nanosecondgenerator (gap of 10...12 mm) the charge losses value does not exceed 12 %. The half of electron scattering angle is 68° at small anodecathode gaps and it decreases with the gap increase down to 60°.

Iron-free electron synchrotron with weak focusing

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