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TY - CONF AU - Boine-Frankenheim, O. AU - Hofmann, I. AU - Struckmeier, J. ED - Petit-Jean-Genaz, Christine ED - Arduini, Gianluigi ED - Michel, Peter ED - Schaa, Volker RW TI - Artificial Collisions, Entropy and Emittance Growth in Computer Simulations of Intense Beams J2 - Proc. of IPAC2014, Dresden, Germany, June 15-20, 2014 C1 - Dresden, Germany T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - During particle tracking with self-consistent space charge artificial collision between the macro-particles lead to diffusion-like, numerical effects. The artificial collisions generate a stochastic noise spectrum. As a consequence the entropy and the emittance of the particle beam can growth along periodic focusing structures. The growth rates depend on the number of simulation macro-particles and on the space charge tune shifts. For long-term tracking studies the numerical diffusion can lead to incorrect beam loss predictions. In our study we present analytical prediction for the numerical friction and diffusion in 2D and 3D simulations. For simple focusing structures with derive a relation between the friction coefficient and the entropy growth. The scaling of the friction coefficient with the macro-particle number and the space charge tune shift is obtained from 2D and 3D simulations and compared to the analytic predictions. PB - JACoW CP - Geneva, Switzerland SP - 1588 EP - 1590 KW - emittance KW - space-charge KW - simulation KW - focusing KW - scattering DA - 2014/07 PY - 2014 SN - 978-3-95450-132-8 DO - 10.18429/JACoW-IPAC2014-TUPRI017 UR - http://jacow.org/ipac2014/papers/tupri017.pdf ER -