HB2012 - List of Authors (Li, K.S.B.)

Paper

Title

Page

Low Gamma Transition Optics for the SPS: Simulation and Experimental Results for High Brightness Beams

381

H. Bartosik, G. Arduini, T. Argyropoulos, T. Bohl, K. Cornelis, J.F. Esteban Müller, K.S.B. Li, Y. Papaphilippou, G. Rumolo, B. Salvant, F. Schmidt, E.N. Shaposhnikova, H. Timko
CERN, Geneva, Switzerland
A.Y. Molodozhentsev
KEK, Ibaraki, Japan

The single bunch transverse mode coupling instability (TMCI) at injection is presently one of the main intensity limitation for LHC beams in the SPS. A new optics for the SPS with lower transition energy yields an almost 3-fold increase of the slip factor at injection energy and thus a significantly higher TMCI threshold, as demonstrated both in simulations and in experimental studies. It is observed furthermore that the low gamma transition optics yields better longitudinal stability throughout the entire acceleration cycle. In addition, simulations predict a higher threshold for the electron cloud driven single bunch instability, which might become an important limitation for high intensity LHC beams with the nominal 25 ns bunch spacing. This contribution gives a summary of the experimental and simulation studies, addressing also space charge effects and the achievable brightness with high intensity single bunch beams.

THO1B05

Broad-band Transverse Feedback against e-cloud or TMCI: Plan and Status

527

C.H. Rivetta, J.M. Cesaratto, J.D. Fox, M.T.F. Pivi, O. Turgut, S. Uemura
SLAC, Menlo Park, California, USA
W. Höfle, K.S.B. Li
CERN, Geneva, Switzerland

The feedback control of intra-bunch instabilities driven by electron-clouds or strong head-tail coupling (Transverse mode coupled instabilities, TMCI) requires bandwidth sufficient to sense the vertical position and apply multiple corrections within a nanosecond-scale bunch. These requirements impose challenges and limits in the design and implementation of the feedback system. To develop the feedback control prototype, different research areas have been pursed to model and identify the bunch dynamics, design the feedback control and implement the GigaHertz bandwidth hardware. This paper presents those R&D lines and reports on the progress as it stands today. It presents preliminary results of feedback systems stabilizing the transverse intra-bunch motion, based on macro-particle simulation codes (CMAD / HeadTail) and measurement results of the beam motion when it is driven by particular excitation signals.

Slides THO1B05 [7.197 MB]

Paper	Title	Page
WEO1B01	Low Gamma Transition Optics for the SPS: Simulation and Experimental Results for High Brightness Beams	381
	H. Bartosik, G. Arduini, T. Argyropoulos, T. Bohl, K. Cornelis, J.F. Esteban Müller, K.S.B. Li, Y. Papaphilippou, G. Rumolo, B. Salvant, F. Schmidt, E.N. Shaposhnikova, H. Timko CERN, Geneva, Switzerland A.Y. Molodozhentsev KEK, Ibaraki, Japan
	The single bunch transverse mode coupling instability (TMCI) at injection is presently one of the main intensity limitation for LHC beams in the SPS. A new optics for the SPS with lower transition energy yields an almost 3-fold increase of the slip factor at injection energy and thus a significantly higher TMCI threshold, as demonstrated both in simulations and in experimental studies. It is observed furthermore that the low gamma transition optics yields better longitudinal stability throughout the entire acceleration cycle. In addition, simulations predict a higher threshold for the electron cloud driven single bunch instability, which might become an important limitation for high intensity LHC beams with the nominal 25 ns bunch spacing. This contribution gives a summary of the experimental and simulation studies, addressing also space charge effects and the achievable brightness with high intensity single bunch beams.

THO1B05	Broad-band Transverse Feedback against e-cloud or TMCI: Plan and Status	527
	C.H. Rivetta, J.M. Cesaratto, J.D. Fox, M.T.F. Pivi, O. Turgut, S. Uemura SLAC, Menlo Park, California, USA W. Höfle, K.S.B. Li CERN, Geneva, Switzerland
	The feedback control of intra-bunch instabilities driven by electron-clouds or strong head-tail coupling (Transverse mode coupled instabilities, TMCI) requires bandwidth sufficient to sense the vertical position and apply multiple corrections within a nanosecond-scale bunch. These requirements impose challenges and limits in the design and implementation of the feedback system. To develop the feedback control prototype, different research areas have been pursed to model and identify the bunch dynamics, design the feedback control and implement the GigaHertz bandwidth hardware. This paper presents those R&D lines and reports on the progress as it stands today. It presents preliminary results of feedback systems stabilizing the transverse intra-bunch motion, based on macro-particle simulation codes (CMAD / HeadTail) and measurement results of the beam motion when it is driven by particular excitation signals.
	Slides THO1B05 [7.197 MB]