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Franchetti, G.

Paper Title Page
TUPEB038 Nonlinear Dynamics Induced by 1-D Model of Pinched Electron Cloud 1608
 
  • G. Franchetti
    GSI, Darmstadt
  • F. Zimmermann
    CERN, Geneva
 
 

The presence of an electron cloud in an accelerator generates a number of interesting phenomena. In addition to electron-driven beam instabilities, the electron "pinch" occurring during a beam-bunch passage gives rise to a highly nonlinear force experienced by individual beam particles. A simple 1-dimensional model for the effect of the electron pinch on the beam reveals a surprisingly rich dynamics. We present the model and discuss simulation results.

 
WEOBRA01 Benchmarking of the NTRM Method on Octupolar Nonlinear Components at the CERN-SPS Synchrotron 2435
 
  • G. Franchetti, A.S. Parfenova
    GSI, Darmstadt
  • R. Tomás, G. Vanbavinckhove
    CERN, Geneva
 
 

The measurement of synchrotron nonlinear components is an essential step for devising an effective compensation scheme for improving machine performances. A validation test of a recently proposed method called nonlinear tune response matrix (NTRM) for measuring circular accelerator nonlinear components is undergoing in a CERN-GSI joint effort. The test consists in the attempt of reconstructing few controlled octupolar components in the SPS synchrotron. In this proceeding we report on the SPS benchmarking experiment and discuss the performances the NTRM method applied to this measurements.

 

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Slides

 
THPEB002 Study on Particle Loss during Slow Extraction from SIS-100 3876
 
  • S. Sorge, O. Boine-Frankenheim, G. Franchetti
    GSI, Darmstadt
  • A. Bolshakov
    ITEP, Moscow
 
 

The heavy ion synchrotron SIS-100 will play a key role within the future FAIR project underway at GSI. Although this synchrotron is optimized for fast extraction, also slow extraction will be used. Slow extraction is based on beam excitation due to a third order resonance. The spread in the particle momenta generating a tune spread causes particle loss leading to an irradiation of the machine especially in a high-current operation. A major part of the losses is assumed to occur at the electro-static separator. In the present study we apply a tracking method to model the extraction process to predict the losses, where, in a first step, high current effects are not taken into account.

 
THPEB003 Determination of the Acceptance of SIS-18 using an RF Voltage 3879
 
  • S. Sorge, G. Franchetti, A.S. Parfenova
    GSI, Darmstadt
 
 

The present heavy ion synchrotron SIS-18 will be upgraded to be used as a booster for further synchrotrons being part of the FAIR project underway at GSI. We present a technique to measure the acceptance of an accelerator based on the extension of a previous method by the measurement of particle loss which we have applied to SIS-18. Here, we used an RF voltage to transversally excite a coasting heavy ion beam. The resulting transverse growth of the beam leads to particle loss when the beam width exceeds the limiting aperture. The acceptance has been determined from the time evolution of the beam current measured after particle have started to hit the aperture.