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KRAKEN, a numerical model of RHIC impedances

Description: The simulation code KRAKEN confirms analytical predictions of head-tail stability criteria, in the presence of momentum dependent linear coupling. It also confirms that resistive wall transverse wake fields are not a serious threat to strong head-tail stability in RHIC, at the vulnerable stage of proton injection. Equation 10, derived from the perspective of two macroparticles, potentially offers a very convenient seminumerical evaluation of the effects of arbitrary transverse wake potentials. It remains to be seen how well the two macroparticle results correlate with simulations using, say, 100 macroparticles. KRAKEN is still under rapid development. Future plans are to include resonant wakefields, multiple bunches, space charge wakefields, betatron detuning, and a connection to the detailed RHIC impedance database.
Date: May 1, 1995
Creator: Peggs, S. & Mane, V.
Partner: UNT Libraries Government Documents Department

RADON reconstruction in longitudinal phase space

Description: Longitudinal particle motion in circular accelerators is typically monitoring by one dimensional (1-D) profiles. Adiabatic particle motion in two dimensional (2-D) phase space can be reconstructed with tomographic techniques, using 1-D profiles. A computer program RADON has been developed in C++ to process digitized mountain range data and perform the phase space reconstruction for the AGS, and later for Relativistic Heavy Ion Collider (RHIC).
Date: July 1, 1997
Creator: Mane, V.; Peggs, S. & Wei, J.
Partner: UNT Libraries Government Documents Department

RHIC injection kicker impedance

Description: The longitudinal impedance of the RHIC injection kicker is measured using the wire method up to a frequency of 3 GHz. The mismatch between the 50 ohm cable and the wire and pipe system is calibrated using the TRL calibration algorithm. Various methods of reducing the impedance, such as coated ceramic pipe and copper strips are investigated.
Date: May 1, 1995
Creator: Mane, V.; Peggs, S.; Trbojevic, D. & Zhang, W.
Partner: UNT Libraries Government Documents Department

Estimation of collective instabilities in RHIC

Description: The authors have estimated the broadband impedance in RHIC to be {vert_bar}Z/n{vert_bar} < 1.2 {Omega} for frequencies above 100 MHz. The Z/n threshold is set for Au{sup +79} ions at transition with an estimated 10% growth in emittance for Z/n = 1.5 {Omega}. They summarize the sources of broad and narrow band impedances in RHIC and investigate the multibunch instability limits throughout the machine cycle. The largest contribution to the broadband impedance comes from the abort and injection kickers. Since RHIC is designed to accelerate fully stripped ions from H{sup +} up to Au{sup +79} they give results for both protons and gold ions; other ions should give results somewhere between these two extremes. All ion species are expected to be stable during storage. At lower energies damping systems and chromaticity corrections will limit any growth to acceptable levels during the short time it takes to inject and accelerate the beams.
Date: May 1, 1995
Creator: MacKay, W.W.; Blaskiewicz, M.; Deng, D.; Mane, V.; Peggs, S.; Ratti, A. et al.
Partner: UNT Libraries Government Documents Department