The Vlasov-Maxwell equations are used to investigate properties of the electron-ion two-stream instability for a continuous, high-intensity ion beam propagating in the zdirection with directed axial velocity Vb = βbc through a background population of (stationary) electrons. The analysis is carried out for arbitrary beam intensity, consistent with transverse confinement of the beam particles, a...

The hollow plasma channel is analyzed as an accelerating structure. The excitation of the channel by an ultrarelativistic beam is analyzed. Coupling to the fundamental and all higher-order azimuthal modes of the excited electromagnetic fields is derived. Implications of this work for plasma-based accelerators, including beam loading and beam breakup, are discussed. Small initial transverse disp...

The hollow plasma channel is analyzed as an accelerating structure. The excitation of the channel by an ultra-relativistic beam is analyzed. Coupling to the fundamental and all higher order azimuthal modes of the excited electromagnetic elds is derived. Implications of this work for plasma-based accelerators, including beam loading and beam breakup, are discussed. Small initial transverse displ...

Evidence is presented to show the transfer, via a collective electrostatic instability, of transverse energy to the longitudinal direction if the axial temperature of a beam is sufficiently low. Two-dimensional r,z electrostatic PIC simulations of a long coasting space-charge-dominated beam propagating in a uniform focused channel are presented to illustrate, for typical parameters, the develop...

In this Letter we discuss a novel method for generating ultrashort radiation pulses using a broadband two-stream instability in an intense relativistic electron beam. This method relies on an electron beam having two distinct two-energy bands. The use of this new high brightness electron beam scenario, in combination with ultrashort soft x-ray pulses from high harmonic generation in gas, allows...

In recirculating accelerators, and, in particular, energy-recovery linacs, the maximum current can be limited by multipass, multibunch beam breakup (BBU), which occurs when the electron beam interacts with the higher-order modes (HOMs) of an accelerating cavity on the accelerating pass and again on the energy recovering pass. This effect is of particular concern in the design of modern high ave...

We suggest a novel type of composite spatial optical soliton created by a coherent vortex beam guiding a partially incoherent light beam in a self-focusing nonlinear medium. We show that the incoherence of the guided mode may enhance, rather than suppress, the vortex azimuthal instability, and we also demonstrate strong destabilization of dipole-mode solitons by partially incoherent light.

A longitudinal single-bunch instability [1] in the damping rings at the Stanford Linear Collider (SLC) is thought to contribute to pulse-to-pulse orbit variations in downstream accelerator sections. To better understand this instability, we measured the beam phase and bunch length under harmonic modulations of the rf phase and rf voltage. For small phase-modulations the measured response can be...

In storage rings which operate with trains of bunches at high currents the observation of the motion of these bunches is quite important. An important reason is that the storage ring is often attempting to operate at or above the instability threshold for coupled bunch instabilities of the beam(s) and these observations are necessary to help to identify the cause of the instability and its poss...

Microwave instability in the Low Energy Ring of KEKB was studied using a broadband impedance model. The model gave excellent descriptions of longitudinal dynamics for both positive and negative momentum compactions. Moreover, it predicted that the threshold of microwave instability was a factor of two lower than the machine nominal operating bunch current. The prediction was confirmed by a meas...