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A NEW BEAM EXTRACTION SCHEME FROM A SYNCHROTRON USING A MAGNETIC SHIELD AS A SEPTUM |
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A.V. Bondarenkoª, S.V. Miginsky, N.A. Vinokurov Budker Institute of Nuclear Physics Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia Abstract A new scheme of beam extraction from a synchrotron is put forward. The main difference from other schemes of extraction is the use of magnetic shields instead of a septum. The magnetic shields are located in the central dipole magnets of a pulsed chicane. A magnetic shield is a multi-layer copper-iron tube. The presented numerical simulations and experimental results for the magnetic shields are in good agreement. The advantages and the area of application of the new extraction scheme are discussed. The proposed scheme will be used for extraction from the booster synchrotron to the storage ring of the new synchrotron radiation source in Novosibirsk. ª corresponding author |
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ALTERNATING WAKE FORCE IN RECTANGULAR WAVEGUIDE WITH PERIODIC PERTURBED WALLS |
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A. Opanasenkoª National Science Center Kharkov Institute of Physics and Technology, Kharkov, Ukraine Abstract The wake field excited by a relativistic charged bunch in a periodic waveguide can be expressed as a spatial harmonic Floquet series. Usually spatial harmonics of the wake force synchronous with the bunch are of interest due to their action on particles that results in the well known beam loading and beam break up effects in rf structures. However, an alternating transverse wake force which consists of nonsynchronous harmonics can give rise to undulating the particles with alternating transverse velocity that can result in no less important effect such as the wake field undulator radiation [1]. Therefore there exist an interest in developing of methods of calculation of alternating wake forces in a periodic rf structures. In this work a perturbation method for calculation of wake field in rectangular periodic waveguides was considered. A possible usage of the wake field excited by an electron bunch passing through a sub-millimeter planar periodic waveguide for both ultra-high gradient acceleration and generation of the hard wake field undulator radiation is discussed. ª corresponding author |
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ANALYTICAL DESCRIPTION OF BETATRON OSCILLATIONS IN LINEAR MACHINES |
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O.E. Shishaninª Moscow State Industrial University, Moscow, Russia Abstract As pointed out by Wiedemann, there are three basic periodic lattices using usually in storage rings [1, 2]. Among these are the FODO, Chasman-Green lattice and triplet. They have not sextupole and octopole lenses and define so-called linear machines. To facilitate the calculations the consideration is restricted only to systems with quadrupole magnets. The equations of small deviations are derived in linear approximation. It is established that these expressions are specific differential equations with periodic coefficients and small parameter of the highest derivative. The Hill equations with a formula for the angular velocity determine the charged particle dynamics. ª corresponding author |
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CALCULATIONS OF THE BEAM TRANSMISSION AND QUALITY IN THE RIKEN AVF CYCLOTRON |
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S.B. Vorozhtsovª¹, A.S. Vorozhtsov¹, E.E. Perepelkin¹, S. Watanabe², S. Kubono², T. Mitsumoto³, A. Goto³ ¹Joint Institute for Nuclear Research, Dubna, Russia ²Center for Nuclear Study, Wako, Japan ³The Institute of Physical and Chemical Research, Wako, Japan Abstract The highly advanced plan of the RIKEN AVF cyclotron (Japan) is under way. The intensity of the 14N5+ ion beam more than 10 pμA is required to obtain a sufficient yield of secondary particles. The computer model of the AVF electromagnetic field has been prepared and successfully checked against the measurements. The focus of the present study is on the 2nd RF harmonic regime. The intermediate goal of the upgrade is improvement of the transmission efficiency and the beam quality of the regime. Measured Hyper ECR output emittances were 64 and 135 π∙mm∙mrad, from which the emittance of 100 π∙mm∙mrad was assumed for both transverse oscillations in the simulation. The detailed account of the transmission efficiency and incremental losses are given. The optimization of the starting beam parameters for the existing electrode structure was considered first. The goal is to obtain a sufficiently small axial angle at the exit from the inflector to decrease axial losses in the initial turns. To this end, a new regime was formulated. The ECRIS voltage and the dee voltage were decreased by 15% to 9 kV and 40 kV, respectively. The modification is needed to ensure the beam passage through the puller with the crossing of the 1st acceleration gap at the positive RF phase that gives the electrical focusing there. Accordingly, the buncher voltage should be changed to 125 V. As a result, the RF phase range of the bunched beam became ±12° and energy spread ±0.8keV with the tails of ~25% of the beam intensity. The magnetic field variation by ~50% of the maximal contribution of the 1st trim coil is needed to ensure acceleration at the top of the dee voltage. The RF frequency 16.2 MHz was assumed. The particle losses in the range from the inflector ground to the ESD mouth became ~35% instead of previous ~60%. The obtained regime was tested experimentally at the AVF cyclotron before proceeding to a more radical modification of the central region as the next step. ª corresponding author |
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CBDA CYCLOTRON BEAM DYNAMICS ANALYSIS CODE |
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E.E. Perepelkinª, S.B. Vorozhtsov Joint Institute for Nuclear Research, Dubna, Russia Abstract A need for intense cyclotron beam requires to minimize the particle losses during injection, acceleration and extraction from the machine. More importance is given to the computational tools that are needed to optimise the design. The 3D CBDA program has been prepared for this purpose. The basic features of this code are: 1) The accelerated beam axial motion with analysis of the particle losses at the limiting aperture surfaces to estimate the transmission efficiency of the beam through cyclotron; 2) Very detailed 3D electrical and magnetic field maps generated and introduced into the code; 3) Simulation of the space charge dominated beam acceleration; taking into account Coulomb repulsion of particles in the beam by PIC (FFT) and PP methods; 4) Enhanced post-processing of the results by means of MathCAD and AutoCAD/SolidEdge software. Some efforts were undertaken to provide user friendliness of the code, including initial documentation and its menu driven operation. Several cross checks of the CBDA simulation results (fields and beam dynamics) compared with other studies have been successfully performed. A number of applications of the code simulate the functionality and design of various cyclotrons is given. They are: VINCY Cyclotron (Belgrade) [1]; 1.747 MeV, 5 mA, H- Customs cyclotron [2]; RIKEN AVF cyclotron (Japan) [3] etc. The present status of the code allows to provide efficient and realistic beam dynamics analysis for the new cyclotron design and operational cyclotron upgrade. ª corresponding author |
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COMPUTATIONAL SIMULATION AND EXPERIMENTAL RESEARCH OF BEAM RF CAPTURE INTO IHEP BOOSTER |
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A. Gurevichª, P. Chirkov Institute of High Energy Physics, Protvino, Russia Abstract The results of the numerical and experimental investigations of the beam RF capture in the booster fast-cycling proton synchrotron are presented in this report. The existing features of the magnetic field cycle of the accelerator are taken into account in the simulation. The time dependence of the RF voltage as well as the moment of the beam injection (during the field cycle) have been optimized to get the maximum efficiency of the capture. The experimental results giving nearly 100% beam cap¬ture in the Booster are presented. ª corresponding author |
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CORRECTING THE ROUND BEAM LATTICE OF VEPP-2000 COLLIDER USING ORBIT RESPONSE TECHNIQUE |
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A.L. Romanovª, D.E. Berkaev, A.N. Kirpotin, I.A. Koop, E.A. Perevedentsev, Yu.A. Rogovsky, P.Yu. Shatunov, D.B. Shwartz Budker Institute of Nuclear Physics Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia Abstract Round colliding beams option in VEPP-2000 [1] puts a number of strict requirements on the collider lattice. The orbit Response Matrix (ORM) technique is a versatile tool for lattice analysis and correction. For linear optical function study and correction, the orbit response to the dipole correctors is collected and processed, while for the orbit correction the quadrupole trimming is used. Theoretical and experimental responses of closed orbit to the same perturbations are compared to determine the most probable deviations of chosen parameters from its design values. ª corresponding author |
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CORRECTION TERMS TO PANOFSKY-WENZEL FORMULA AND WAKE POTENTIAL |
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A. Opanasenkoª National Science Center Kharkov Institute of Physics and Technology, Kharkov, Ukraine Abstract In their 1956 article [1] Panofsky and Wenzel derived a relation for the net transverse kick experienced by a fast charge particle crossing a closed cavity excited in a single rf mode. Later this relation, usually referred to the Panofsky-Wenzel theorem, was generalized for cavity containing wake field induced by a driving charge. This theorem has played very important role in accelerator physics. One well-known conclusion of this paper was that in a TE mode the deflecting impulse of the electric field always cancels the impulse of the magnetic fields. In our presentation we more exactly rederive Panofsky and Wenzel's result and obtain correction terms to the transverse kick. We show that in a TE mode the net transverse kick is not zero. Using the given approach we find correction terms to wake potentials which turn out to be inversely proportional to the relativistic factor. Practical implications of our results are discussed. ª corresponding author |
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EXPERIMENTAL RESULTS OF THE BEAM DYNAMICS BY USING GLASS CAPILLARIES FOR THE ESA-2 |
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A.E. Lagutinª, A.N. Sevchenko A.N. Sevchenko Scientific Research Institute of Applied Physical Problems, Belarussian State University, Minsk, Belorussia Abstract In comparison with the existing tools for formation of micrometer-sized beams, capillary method is undoubtedly simpler and less expensive. At the same time, is satisfies all the requirements of submicron Rutherford backscattering spectrometry or analysis with application of induced characteristic X-rays. The processes of interaction of accelerated protons with the surface of insulating capillaries have been investigated to determine the character of motion of particles during such interaction. The angular distributions of 240 keV protons transmitted through glass capillaries have been measured, and splitting of the distribution into a series of lines equally spaced from each other is revealed. Protons passed through the glasses (boron-silicon) capillaries with a diameter of 0.1, 0.5 and length of 30, 65, 178 mm at the axial entry angles of particles ± 0.2º and in the range of proton beam currents from 8.5∙10-13 to 10-11 A. Ion-optical characteristics of an tapered glass capillary were studied. We present evidence of the focusing effects of fine glass capillary optics for proton ion beams. The glass capillary optics is formed by a puller as to have inlet diameters of about 3 mm and outlet diameters of submicrons. The total length of the optics is about 80 mm. Impingent 240 keV protons to such optics are reflected by the inner wall several times, in a very similar process to the so-called surface channeling. ª corresponding author |
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IMPLEMENTING ELEMENTS OF DIGITAL TRANSVERSE FEEDBACK SYSTEM IN ALTERA FPGA |
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E.V. Gorbachevª, N.I. Lebedev, V.M. Zhabitsky Joint Institute for Nuclear Research, Dubna, Russia Abstract The transverse feedback system is intended to damp beam position errors after injection into an accelerator and cure beam instabilities during acceleration. The system consists of pick-ups, low level electronics making necessary signal processing and power electronics. Implementation of the low level electronics elements in Altera StratixII DSP development kit is described. The realized digital signal processing allows keeping an optimal phase between pick-up and kicker with changes of revolution frequency during accelerating cycle. ª corresponding author |
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INCOHERENT VERTICAL ION LOSSES AT COOLING STACKING INJECTION |
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A. Smirnov, E. Syresinª Joint Institute for Nuclear Research, Dubna, Russia Abstract The efficiency of the cooling-stacking injection depends on two parameters: the cooling-accumulation efficiency and the ion lifetime. The lifetime of newly injected ions is usually smaller than the stack lifetime of high intensity ion beams. The incoherent losses of newly injected ions are related to multiscattering on residual gas atoms and vertical heating caused by ion stack noise. The short lifetime of newly injected ions restricts the efficiency of the cooling stacking injection. The experimental dates, analytical estimations and BETACOL simulations of vertical incoherent ion losses at cooling stacking injection are discussed. ª corresponding author |
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ION BEAM ACCELERATION IN INDEPENDENTLY PHASED CAVITIES |
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E.S. Masunovª, A.V. Samoshin Moscow Engineering Physics Institute (State University), Moscow, Russia Abstract Ion superconducting linac is based on an array of short identical niobium cavities. By specific phasing of the RF cavities one can provide a stable particle motion in the whole accelerator. The longitudinal and transverse ion beam dynamics are studied in this linac. The equation of motion in the Hamiltonian form is devised by the smooth approximation. The focusing methods by the solenoid field and RF field are studied. The results of this investigation are compared with the matrix calculation of ion beam dynamics in superconducting linac. ª corresponding author |
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NARROW-BAND FEEDBACK SYSTEM TO DAMP TRANSVERSE COHERENT OSCILLATIONS OF BEAM IN THE U70 |
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O. Lebedevª, S. Ivanov, N. Ignashin, S. Sytov Institute of High Energy Physics, Protvino, Russia Abstract Resistive-wall transverse coherent instability shows up as a major adverse factor in running the U70 proton syn-chrotron of IHEP-Protvino. The 10th azimuthal spatial harmonic of coherent beam perturbation is the worst one prone to a strong instability. To damp this particular beam mode selectively, a dedicated narrow-band feedback cir-cuit has been developed. All of its hardware (comprising beam pickup and kicker plus analogue processing elec-tronics) is housed in one and the same straight section of the ring lattice, the feedback circuit configuration thus being the local one. Such a straightforward layout mini-mizes inherent time delays and eases closing the two feedback loops servicing horizontal and vertical direc-tions. The paper contains a brief technical specification of the damping system. Experimental results acquired during its turning on and beam-testing are outlined. ª corresponding author |
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NEW SCHEME FOR MAGNETIC COMPRESSION OF THE MULTIPLE BEAM AT THE POWERFUL MULTI-BEAM KLYSTRON |
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A. Larionovª Physicotechnical Center of Lebedev Physical Institute, Protvino, Russia Abstract This paper describes the design of the optical system of the powerful multi-beam klystron (MBK) that provides approximately twofold radial compression of the generated multiple beam. The basic advantage of this design is that the multiple beam is formed in the flat-type gun. The compression of the multiple beam and its matching with a solenoid magnetic field are also carried out, use being made of the set of simple magnetic lenses. Lenses are designed in form of the solenoid sister-coils and separated by the flat iron screens with the apertures for individual beamlets. The optical system in question may be applied in a low-voltage (60 kV) 10 MW L-band MBK for the ILC (International Linear Collider) as well as in a 10 MW X-band MBK to support the accelerating technologies being now under development at KEK (Japan). Herein are presented the results of the 3D simulation of the multiple beam optics for the mentioned above applications. ª corresponding author |
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POWER COUPLER FIELD ASYMMETRY INFLUENCE ON PARTICLE BEAMS DYNAMICS IN ACCELERATORS WITH SUPERCONDUCTING CAVITIES |
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M.V. Lalayanª¹, V.A. Makarov¹, N.P. Sobenin¹, V.I. Shvedunov², A.A. Krasnov³, A.A. Zavadtsev³ ¹Moscow Engineering Physics Institute (State University), Moscow, Russia ²Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia ³Scantech Sciences LLC, Atlanta, USA Abstract An investigation of input coupler asymmetry influence on electron beam's dynamics in energy recovery linacs (ERL) with superconducting cavities was carried out. There were considered several types of input power couplers coaxial and waveguide, asymmetric and symmetric. Based on numerical modeling distribution of electromagnetic fields in accelerating cavity with input coupler was found, the transverse deflecting impulse was calculated. RTMTRACE software was adapted for beam's dynamics modeling. ª corresponding author |
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SIMULATION OF PELLET TARGET EXPERIMENTS WITH BETACOOL CODE |
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A. Smirnov¹, A. Sidorin¹, D. Krestnikovª¹, R. Pivin¹, D. Prasuhn², M. Wolke² ¹Joint Institute for Nuclear Research, Dubna, Russia ²Institut für Kernphysik, Forschungszentrum Jülich GmbH, Jülich, Deutsch Abstract In last years at GSI (Germany) new accelerator complex project FAIR is being realized. One of the most important goals of this project is caring out an experiment with internal target PANDA [1]. The only way to achieve design luminosity value is to use a pellet target. However, such a target is coming up with short-scale luminosity variation. Peak to mean luminosity ratio can reach a big value unacceptable for detector. A numerical simulation of this experiment is connected to two different time-scale processes. The first one is the short-time process, which describes luminosity variations while one pellet is crossing the beam. This process can be about tenths microsecond long. The long-time process of the beam parameter evolution (particle number, transverse and longitudinal profiles) are defined by the beam losses and equilibrium between target heating and electron cooling. This article presents the numerical simulations with BETACOOL code [2] which allows solving both these tasks. ª corresponding author |
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SIMULATION STUDY OF STABLE AND MOVING BARRIER BUCKETS USING BETACOOL CODE |
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A. Smirnov, A. Sidorin, R. Pivinª, D. Krestnikov Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences, Tomsk State University, Tomsk, Russia Abstract A moving barrier RF bucket is an effective ion beam accumulation method used, for instance, in Fermilab's Recycler and proposed for NESR at FAIR project. A possible application of a stationary RF bucket is to compensate an ionization energy loss in experiments with an internal target. The ionization energy loss is the main physical effect limiting the experiment duration. The barrier bucket application permits to sufficiently decrease of a required power of a cooling system when a high resolution in an experiment is necessary[1]. Recently a new program was developed for barrier RF bucket simulation for FAIR rings [2]. To compare predictions of different models and to estimate efficiency of the barrier bucket application in internal target experiments the new algorithms were implemented into Betacool program [3] also. ª corresponding author |
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TEST OF THE PLASMA LENS OF THE ITEP ION ACCELERATOR |
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A. Drozdovskiyª, A. Golubev, B. Sharkov, M. Basko, D. Iosseliani, A. Kantsyrev, A. Kuznetsov, Yu. Novozhilov, P. Sasorov, S. Savin, V.V. Yanenko, V. Abramenko, O. Pronin Alikhanov Institute for Theoretical and Experimental Physics, Moscow, Russia Abstract The problem of focusing of intense heavy-ion beams is an important issue for investigating high energy densities in matter. Application of a plasma lens to this area of research has a number of essential advantages in comparison with the traditional system on the basis of quadruple lenses. At ITEP the plasma lens has been designed and installed into the exit channel of the TWAC accelerator complex. The description of the plasma lens and the results of the first experiments with this lens are reported. ª corresponding author |
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THE FORMATION OF ELECTRONS BEAMS IN GAS UNDER ATMOSPHERIC PRESSURE |
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V.A. Shklyaevª, K.P. Artyomov, S.Ya. Belomyttsev, A.A. Grishkov, V.V. Ryzhov, I.Yu. Turchanovsky Institute of High Current Electronics, Siberian Branch of the Russian Academy of Sciences, Tomsk State University, Tomsk, Russia Abstract In this work results of numerically researches of the formation of runaway electrons beam in gas under atmospheric pressure presents. It is showed that runaway electrons beam was formed in highly inhomogeneous electric field near the cathode. This beam consists of electrons emitted from cathode and electrons arising as a result of gas ionization. It was showed that duration of the beam of run-away electrons nearby cathode mainly depend on outer electrical field screening by plasma and was equal to 10÷20 ps. Dynamic of acceleration electrons in gas similar to dynamic of acceleration electrons in vacuum. ª corresponding author |
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TRANSVERSE DEFLECTING STRUCTURE PARAMETERS STUDY |
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D. Denisenko, V. Paramonovª Institute for Nuclear Research of Russian Academy of Sciences, Moscow, Russia Abstract Parameters of a periodical traveling wave structure, based on the disk-loaded waveguide with operating HE11 wave, have been considered. The structure is intended for single, or several, bunch extraction from long bunch train. For stability, single mode operations is required and pass bands separation with structure axial symmetry deterioration is investigated. Both backward and forward wave regimes are considered. The aim of investigations is to define cell dimension to provide required particle deflection under limited filling time and restricted RF power. Results of the study are reported. ª corresponding author |
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UAL 3: ASPECT-ORIENTED APPROACH |
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N. Malitskyª¹, R. Talman² ¹Brookhaven National Laboratory, Upton, USA ²Cornell University, Ithaca, USA Abstract The paper presents the next step in the evolution of the Unified Accelerator Libraries (UAL). The existing version is base on an object-oriented framework addressing a broad spectrum of offline modeling applications ranging from configurable efficient integrators to full-scale realistic beam dynamics studies encompassing multiple physical effects. Accumulated experience with various projects has validated the UAL framework and outlined its relationship with the new aspect-oriented paradigm (AOP). As a result, the UAL3 version is designed to develop and apply the AOP Conceptual Reference Module in the context of the accelerator computational physics domain. ª corresponding author |
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VARIOUS MATRIX FORMALISM TO DESIGN ION LINEAR ACCELERATORS |
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V.A. Moiseevª, S.E. Bragin Abstract The well-known betatron function parameterization in the beam optical computations provides an emittance independent representation of the properties of a beam transport system. The acceleration effects lead to nonsymplecticity of the transfer matrix. The error analysis of matrix presentation in the different phase spaces has been carried out. The coupling transformations of betatron functions for the studied phase spaces are presented. ª corresponding author |
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