Ashida, K

Harada, S

Harami, T

Hashimoto, H

Iizuka, M

Ishida, T

Kabasawa, Mitsuaki

Kamitsubo, H

Mashiko, K

Nakayama, K

Ohtsuka, H

Shimada, T

Suzuki, H

Suzuki, Y

Yamada, K

Yanagida, K

Yokomizo, H

Yoshikawa, H

CERN Document Server

Particle Accelerators, 1990, Vol. 33, pp. 63-68Reprints available directly from the publisherPhotocopying permitted by license only© 1990 Gordon and Breach, Science Publishers, Inc.Printed in the United States of AmericaINJEcrOR DESIGN FOR 1HE 8 GEV SYNCHROTRON RADIATION FACILITYIN JAPANTAIKAN HARAMI, HIDEAKI YOKOMIZO, HIDEO OHTSUKA,TAIREl SHIMADA, KENICHI YANAGIDA, KATSUO MASHIKO,HIROSHI YOSHIKAWA, HIROMITSU SUZUKI, MITSUAKI KABASAWA,KOICHI NAKAYAMA, HIROSHI HASHIMOTO, KAZUO ASHIDA,TSUTOMU ISHIDA, KOHJI YAMADA, MOTOAKI IIZUKA, SHUNTI HARADA,YASUO SUZUKI, HIROMICHI KAMITSUBOJAERI-RIKEN Synchrotron Radiation Facility Design TeamJAERI, Tokai-mura, Naka-gun, Ibaraki-ken, 319-11, JapanAbstract The improved injection system consists of a 1.0 GeV linac and a 1 Hz, 8 GeVsynchrotron(circumference 396 m) for the synchrotron radiation facility planned inJapan.The natural emittance of the synchrotron with a racetrack shape of lattice is about1.95 x 10-7 m ·rad at 8 GeV, which is expected to be satisfactory for subsequent injectioninto the storage ring.INTRODUCfIONThe design, research and developments are under way to construct the new facility for a highbrilliant synchrotron photon source in Japan 1. The project is carried forward by Japan AtomicEnergy Research Institute(JAERI) and the Institute of Physical and ChemicalResearch(RIKEN), under the supervision of Science and Technology Agency(STA) of ourgovernment.The injection system was frrst designed on a rather large scale taking into account the futureextensive use of the facilities2 • In the meantime, the design of the injection system has beenimproved to be reasonable by the consideration of the injection efficiency into the storage ringand the cost. The improved injection system consists of a 1.0 GeV linac and a 1 HZ,8 GeVsynchrotron (circumference 396 m).The two basic modes of operation, the multibunch and single bunch charging of the storagering, are considered with the loaded beam current of 100 rnA and 5 rnA, respectively. The in-jection system is capable of filling the storage ring to its full current of electrons within twominutes on the assumption that the transmission of electrons is about 30 % from the exit of thelinac to the storage ring. In the case of using positrons instead of electrons, the filling time willbe significantly longer than with electrons. A positron accumulating and damping ring isconsidered as an option to be installed.[1753]/6364/[1754]LINACT. HARAMI ET AL.Table I Linac parametersTable 2 Synchrotron parametersThe linac is made up of three parts to ac-celerate electrons and positrons. The firstsection is a 50 MeV electron linac, fol-lowed by the second section of the linac toaccelerate electrons up to I GeV for theinjection into the synchrotron. The thirdsection is a 200 - 250 MeV high-currentelectron linac that impinges on a con-verter target to generate the positrons.The positrons are focused through apulsed solenoid magnetic field and thenaccelerated by the second section of thelinac.Some of the major parameters of the linacsystem are listed in Table I. The pulseswith a narrow width of I nsee are plannedto be produced by a combined way of agrid pulser,a subharmonic buncher andbunchers. An option is considered for themacropulse waveform of electronswhich has successive 500 pulses with theInsec width at every 2 nsec interval.The linac is designed to operate at themaximum frequency of 60 Hz. The accel-eration tubes are 21C/3 traveling wavemode and each is about 3 m long.An energy compression system (ECS) ,made up of dipole magnets and a radiofrequency cavity is planned to be attachedto the end of the linac to minimize theenergy spread of the electron beam fromthe linac.SYNCHROTRONThe synchrotron is designed to accelerateEnergyRepetition rateFrequencyMultibunch mode(e-)Peak currentPulse lengthSingle bunch mode(e-)Peak currentPulse lengthMultibunch mode(e+)Peak currentPulse lengthSingle bunch mode(e+)Peak currentPulse lengthInjection energyMaximum energyRadiation lossNominal tunesBeam emittanceNat. chromaticityMometum compactionBending magnetsfieldbending radiusQuadrupole magnetsfieldSextupole magnetsfieldRF systemfrequencyharmonic numbervoltageQuantum lifetime1.0GeV60Hz2856 MHz100 rnAI ms300mAInslOrnAIOnslOrnAIns1.0GeV8.0GeV11.5MeV/tum11.73(x)/8.78(y)1.95 x 10-7 m·rad-15.3/-12.79.51 x 10-30.85 T (8 GeV)31.4m14.5 TIm (QF)12.5 T/m (QD)201.3 T/m2 (SF)162.7 T/m2 (SD)508.58 MHz67217.1 MV (8 GeV)over 10 secondsINJECTOR DESIGN [1755]/65electrons injected from the linac at an energy of 1 GeV to the full energy of the storage ring of8 GeV. The synchrotron lattice is based on a separated function FODO arrangement ofmagnets3• There are four dispersion-free straight sections on qJposite sides of the synchrotrongiving a racetrack shape. Injection is on one side and extraction on the other side. 8 rf cavities(fRF=508.58 MHz) are located in two straight sections upstream of the injection and theextraction regions (4 cavities in each region). Some of the major parameters of the synchrotronare shown in Table2.LatticeThe injector synchrotron has 40 FODO cells. There are 32 normal cells in the lattice.Dispersion is suppressed by removing a bending magnet from a nonnal cell, followed by a fullempty cell.The horizontal and vertical tunes are, 11.73 and 8.78. Figure 1 shows the lattice functions forthese particular tunes. Four dispersion-free straight sections are 4.35 m long. The naturalemittance at 8 GeV is 1.95 x 10-7 m·rad. This value of emittance is expected to be quitesatisfactory for subsequent injection into the storage ring. The natural chromaticities of thelattice are ~x= -15.3 and ~y= -12.7. To correct the chromaticities, 16 focusing and 32defocusing sextupoles, each 0.15 m long, are placed near focusing and defocusing quad-rupoles. The sextupole strength are 201.3 T/m2 for the focusing and 162.70 T/m 2 for thedefocusing sextupoles.The lattice has a large dynamic aperture according to the calculation performed using thetracking code RACETRACK.The incoming beam rms emittance of 1 x 10-6 m ·rad, the maximum ~ function of 16.7 m andthe maximum dispersion function of 1.0 m give rms beam size of 9.1 mm at the quadrupolesFig. 1 ~ and dispersion functions for the synchrotronbeta x rmleta x rmlbeta y [m]0-+--t~-r-+~~ ..................-4~""'''''''~~~:+-''''''-302520151 0 5 0 5 1015202530s [m]..........EO-+-4oi~~'-'+-""""""---~-+-+-~~~+-+-~-w-t66/[1756] T. HARAMI ET AL.in the horizontal plane.The vertical half-height of the vacuum chamber in the quadmpoles is 18 mm which is 4.4 timesthe nns beam size of 4.1 mm in the vertical plane. The gap of the bending magnet is 45 mm.At injection,incoming linac macropulse is 1 nsec long. The bucket length is more than 1 nsec,which may assure an effective capture efficiency.MagnetsThe major ring magnets for the synchrotron consist of 68 dipoles, 80 quadrupoles and 68sextupoles. These magnets are assembled by stacking 0.5 mm thick silicon steel laminations.The cross section of the magnets has been detennined by 2D calculations using TRIM.The dipoles are specified as H magnets. The pole profile is shown in Fig.2 The pole widthis 150 mm with lateral shims 9 mm wide by 1.2 mm high. The magnetic field variations hasbeen calculated to be L\B/B =5 x 10-4 within an aperture ofx =+ 35 mm, y =+ 15 mm. Thereare no saturation effects with the maximum magnetic field of 1.5 T throughout the yoke.The pole tip of the quarupoles is hyperbolic (equation:xy = (31)2/2) for a total angle of 45° andcontinued by a linear tangent. The magnetic field is correct (Llli/B < lxl0-3) up to x =22mm.The Bohr radius and the length of the sextupole is 42 mm and 0.2 m, respectively.Vacuum systemThe synchrotron ringvacuum system is· de-signed to satisfy the fol-lowing main require-ment; maintain a pres-sure of 1 x 1Q-6 torr witha8GeV lOrnA beam ofelectrons to give a life-time of more than 10seconds due to gas scat-tering.The vacuum chambersare made from 1.5 mmthick stainless steeltubes fonned to a race-track shape. The insidedimensions are 36 mmheight and 72 mmwidth. The eddy cur-Fig. 2 End view of bending magnet for the synchrotron402INJECTOR DESIGN [1757]/67rent effect is negligible. The heating of the chamber due to synchrotron radiation requires noadditional water cooling.RF systemThe rf system is designed to adopt a frequency of 508.58 MHz because of the availability ofsuitable klystrons at this frequency in KEK. The same rf frequency is used as for the storagering. The l{l resonant cavities is shaped nose cone type to optimize the shunt impedance, shownin Fig.3. There are 5 cells per cavity coupled to each other through slots. The effective shuntimpedance is 21 MW/m. The rated dissipation power per cavity is evaluated to be about 150kW. A minimum of 8 cavities may be required to satisfy the synchrotron design parameterspecifications.Fig. 3..Side view of 5 cells rf cavity for the synchrotronAntennaHOM damper HOM damper./'Cooling waterBeam oco~-e-~~~~\~~~~~~~-+-_lir+----- Vacuum pump - 1 7'.7 a--------~BEAM TRANSPORT SYSlEMFigure 4 shows the layout of the injection system and the storage ring. The facility is built onthe ground created in the hilly country of Nishiharima. The injection system and the storagering are based on rock bed. The injection system is planned to be built on the lower groundby about 10m than that of the storage ring.The 60 m beam transfer line from the linac to the synchrotron is composed of the injectionseptum in the synchrotron and bending magnets and quadrupole magnets to match thedispersion function in the synchrotron and the phase-space matching between linac andsynchrotron.The transfer line between the synchrotron and the storage ring is made of three parts. The frrstpart of the transfer line is an achromatic cell. This achromatic cell eliminate the dispersioncreated by the extraction hardware. The dispersion-free second part contains quadrupoles for68/[1758] T. HARAMI ET AL.matching the functions from the synchrotron to those of the storage ring. The third part, whichincludes the storage ring injection magnets, is an achromatic cell that matches the dispersionfunction in the ring. lne total length of the transfer line is about 270 m. This long beam linecan afford a place around the injection system building for the future use of the synchrotronto another application.CONCLUDING REMARKSThe current design, research and development of the injection system was described for the8 GeV synchrotron radiation facility in Japan. The R&D of the hardwares, magnets, rf cavitiesand vacuum chambers for the synchrotron is carried out this fiscal year. The test of the positrongeneration system is planned. The design of the injection system will be improved on the basisof these studies.REFERENCES1. M. Hara, S.H. Be,R. Nagaoka, S. Sasaki, T. Wada and H. Kamitsubo, Proceedings of1989 Particle Accelerator Conference in Chicago.(1989).2. H. Yokomizo, T. Harami, K. Yanagida, K. Mashiko, K. Ashida, K. Nakayama,K.Yamada, H. Konishi, S. Sasaki, Y. Suzuki, H. Kamitsubo, Proceedings of 1989Particle Accelerator Conference in Chicago (1989).3. M. Kabasawa, K. Nakayama, T. Harami, T. Shimada, K. Yanagida and H. Yokomizo,JAERI- M 89-109 (in Japanese) (1989).Fig. 4 Layout of the injection system and the storage ringstorage ring""\ \\\\\\\\\III~\\ synchrotro\"290m "-_ 280m above the sea

Injector Design For The 8-gev Synchrotron Radiation Facility in Japan

Injector Design For The 8-gev Synchrotron Radiation Facility in Japan

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