| Paper |
Title |
Page |
| MOPLT047 |
Lattice Design Study for HESR
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653 |
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- Y. Senichev, S. An, K. Bongardt, R. Eichhorn, A. Lehrach, R. Maier, S. Martin, D. Prasuhn, H. Stockhorst, R. Tölle
FZJ/IKP, Jülich
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The important feature of High Energy Storage Ring is the combination of phase space cooled beams with internal targets, which allows to reach high luminosities up to 2*1032cm-2s-1. However, the requirement to have the strongly focused beam on the target causes the high chromaticity value on the target straight section and as in result to the squeezing of dynamic aperture after sextupole correction of the chromaticity. Simultaneously, the momentum-compaction factor is one of the most important characteristics of an accelerator, which defines the collective instability threshold. Therefore, the HESR lattice has to have the following features: low or negative momentum compaction factor, dispersion free straight sections, convenient method to correct the chromaticity by the sextupoles, sufficiently large dynamic aperture. In this work we develop lattice, which meets all these requirements for HESR.
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| TUPLT043 |
Status of the Cooler Synchrotron COSY-Juelich
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1246 |
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- B. Lorentz, U. Bechstedt, J. Dietrich, R. Eichhorn, R. Gebel, A. Lehrach, R. Maier, D. Prasuhn, A. Schnase, H. Schneider, R. Stassen, H. Stockhorst, R. Tölle
FZJ/IKP, Jülich
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The cooler synchrotron COSY accelerates and stores unpolarized and polarized protons and deuterons in the momentum range between 300 MeV/c to 3.65 GeV/c. To provide high quality beams, an Electron Cooler at injection and a Stochastic Cooling System from 1.5 GeV/c up to maximum momentum are available. Vertically polarized proton beams with a polarization of more than 0.80 are delivered to internal and external experimental areas at different momenta. Externally, the maximum momentum is up to date restricted to approximately 3.4 GeV/c by the extraction elements installed in COSY. In 2003 deuteron beams with different combinations of vector and tensor polarization were made available for internal and external experiments. An rf dipole was installed, which is used to induce artificial depolarizing resonances. It can be used for an accurate determination of the momentum of the stored beams. The status of the cooler synchrotron COSY is presented and future plans are discussed.
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| TUPLT044 |
Delta-T Procedure for Superconducting Linear Accelerator
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1249 |
| |
- A. Bogdanov, R. Maier, Y. Senichev
FZJ/IKP, Jülich
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Development of the tune-up procedure for a linear accelerator is the next important stage after the design is complete. Conventional delta-T procedure developed for tuning of a normal-conducting linear accelerator by Crandall allows setting up of accelerating field amplitude and phase in cavity with known phase velocity. However, application of the delta-T procedure to a superconducting linac meets some difficulties. In particular, the synchronous phase velocity in superconducting linac is determined by RF phase shift between cavities, but not by geometrical size of accelerating cells as in normal conducting linac. Additionally, in superconducting linac the smaller phase advance leads to an insensibility of particles at the cavity exit to the variation of the electric field inside the cavity. In the paper we consider the modified delta-T procedure adjusted for superconducting linac. Numerical simulations prove that by proposed technique both tasks of preservation of necessary stable region motion and providing the beam with required final energy can be successfully solved.
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| TUPLT045 |
Separatrix Formalism Applied to Linacs Accelerating Particles with Different Charge to Mass Ratio
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1252 |
| |
- A. Bogdanov, R. Maier, Y. Senichev
FZJ/IKP, Jülich
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We have developed separatrix formalism for superconducting linear accelerators. This method allows optimizing the quasi-synchronous velocity behavior along a linac. It gives a great advantage in acceleration of particles with different charge to mass ratio. In the article design optimization of structure supposed to accelerate different particles is presented. As an example for numerical simulation superconducting injector COSY is taken.
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| TUPLT046 |
Luminosity Considerations for Internal and External Experiments at COSY
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1255 |
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- A. Lehrach, U. Bechstedt, J. Dietrich, R. Eichhorn, R. Gebel, B. Lorentz, R. Maier, D. Prasuhn, H. Schneider, R. Stassen, H. Stockhorst, R. Tölle
FZJ/IKP, Jülich
- A. Schnase
JAERI/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
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The future physics program at the Cooler-Synchrotron COSY in Jülich requires intense beams to provide high luminosities up to 1032cm-2s-1 for internal and external experiments. In 2003 the number of unpolarized protons could significantly be increased up to the theoretical space charge limit of COSY. This was achieved by careful study and adjustment of all subsystems in the accelerator chain of COSY. The intensities for polarized proton beams are at best an order of magnitude lower compared to one for unpolarized beams, depending on the beam current provided the injector cyclotron. Still there is some potential for further enhancement of polarized beam intensities. In this paper, luminosity considerations for polarized and unpolarized beams at COSY are presented taking into account different machine cycles and operation modes for internal and external experimental set-ups.
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| TUPLT047 |
First Results of Pulsed Superconducting Half-wave Resonators
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1258 |
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- R. Stassen, R. Eichhorn, F.M. Esser, B. Laatsch, R. Maier, G. Schug, R. Tölle
FZJ/IKP, Jülich
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A pulsed linac for the cooler synchrotron COSY was projected based on superconductive half-wave resonators (HWRs). The concept of single phased resonators is a great challenge related to the requirement of accelerating protons and deuterons up to a similar energy. A cryomodule, which houses four cavities was designed in Cooperation with FZJ-ZAT, taking into account the restricted space and the special requirements of a linear accelerator. Two prototypes of the 160MHz Half-Wave Resonators (HWRs) were built at different companies. The fabrication differs slightly concerning the top and bottom parts of the cavity as well as the welding of the inner and outer conductor. First results of warm and cold measurements will be presented. The behaviour of the adjustable 4kW main coupler as well as the mechanical tuner can be tested together with the HWR in a new vertical test-cryostat.
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| TUPLT049 |
Triple-spoke Cavities in FZJ
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1261 |
| |
- E. Zaplatin, W. Braeutigam, R. Maier, M. Pap, M. Skrobucha, R. Stassen, R. Tölle
FZJ/IKP, Jülich
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We report the situation with superconducting triple-spoke cavity activities at the research center FZJ in Juelich. The Nb prototype of the 700 MHz, beta=0.2 cavity is already in fabrication and should be tested this year. This work has been initiated for the European Spallation Source project. In the frames of the new European project of High Intensity Pulsed Proton Injector the 352 MHz, beta=0.48 cavity is under developments. This cavity should be designed, built and tested in the Lab within next few years.
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| WEPLT067 |
Space Charge Problem in Low Energy Super-conducting Accelerator
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1999 |
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- N.E. Vasyukhin, R. Maier, Y. Senichev
FZJ/IKP, Jülich
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At present the super-conducting option of linear accelerators is considered for low energy, and new type of RF cavities is considered for this purpose. However, together with electrodynamics problems we should solve the transverse stability problem, since in structures with external focusing elements the focusing period is longer, and in higher accelerating field the defocusing factor increases as well. In this paper we consider the transverse stability problem, taking into account the non-linear space charge problem. The fundamental mechanism of hallo creation in super-conducting linear accelerators is investigated to minimize the particle losses. The theoretical results are supported by numerical simulation.
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