Synchrotron radiation in electron-positron colliders and synchrotron light sources ejects photoelectrons from the beam chamber walls. The resulting cloud of slow photoelectrons interacts with the beam, and may generate a transverse coupled bunch instability. In some high current storage rings a photoemission effect causes the dominant transverse instability, with a sub-millisecond risetime. Two...

The dynamic characteristics and parametric instability of a rotating electrorheological ER sandwich beam with rotary oscillation are numerically analyzed. Assuming that the angular velocity of an ER sandwich beam varies harmonically, the dynamic equation of the rotating beam is first derived based on Hamilton’s principle. Then the coupling and nonlinear equation is discretized and solved by the...

We report the results of experiments on a “fast beam-ion instability”[1] at the Advanced Light Source (ALS). This ion instability, which can arise even when the ions are not trapped over multiple beam passages, will likely be important for many future accelerators. In our experiments, we filled the ALS storage ring with helium gas, raising the pressure approximately two orders of magnitude abov...

The storage ring at Taiwan Light Source has experienced a strong collective instability since 1994. Various cures have been attempted to suppress this instability, including the use of damping antenna, tunable rf plungers, different filling patterns, and rf gap voltage modulation. So far these cures have improved the beam intensity, but the operation remains to be limited by the instability. Th...

Two-stream instabilities in intense charged particle beams, described self-consistently by the nonlinear Vlasov-Maxwell equations, are studied using a 3D multispecies perturbative particle simulation method. The newly developed beam equilibrium, stability, and transport (BEST) code is used to simulate the linear and nonlinear properties of the electron-proton (e-p) two-stream instability observ...

Attempts to describe analytically the beam-beam interaction in a storage ring are asnumerous as they are disappointing and frustrating. One can find in the literature many different theoretical approaches single resonance models, trapping, linear approximations, resonance overlap models, applications of Lie algebra, etc.? None of them give a satisfactory explanation of the observed phenomena ei...

The foundation of the beam perturbation formalism was established on the Sacherer integral equation [1]. The original solution was obtained by using simplified radial functions, and the results can be used to explain several important beam instability problems. To solve the instabilities caused by high beam intensities calls for more complete solution and the extension to the formalism as well....

gyroscopes are used as rotation rate sensors. conventional gyroscopes are heavy and bulky, which creates important problems regarding their usage in different applications. micro-gyroscopes have solved these problems due to their small size. the beam micro-gyroscope is one of the popular types of inertial sensors. their small dimensions and low energy consumption are key reasons for their popul...

We have studied fast ion instability (FII) in the electron ring (HER) at KEKB. We introduce an application of Singular Value Decomposition (SVD) to study multi-bunch beam oscillations. The SVD analysis[1] has been performed for a matrix consists of vertical bunch positions in a turn-byturn and bunch-by-bunch to extract wave lengths which characterized the behavior of multi-bunch beam instabilit...

In this note we carry out some basic beam-beam studies for the muon collider in the incoherent classical approximation, taking into account the instability of the muon. This collider has a beam-beam parameter value typical of an e+e− collider, and a damping time that is more typical of a hadron collider. We conclude that these characteristics can coexist thanks to the short cycle time forced by...