Strong Space Charge Research Articles

On the Design of a High Intensity Proton Linear Accelerator

In the CERN linear accelerator, intensities above 125 mA have been accelerated. For very big, present and future AG synchrotrons, however, there is a need for injectors giving 200 mA or more. At this intensity level, very strong longitudinal space charge effects occur which limit the phase stability in linacs and which also have been shown to prevent efficient bunching with conventional bunchers. Proposals are given to raise the limit of these effects to about half an ampere where beam loading compensation may become difficult. For a better prediction of the performances, several studies are still to be made and various methods are outlined; a few difficult points may, however, require further effort, especially if still higher intensities and extreme performances are needed.

Adiabatic Electron Fluid in the Presence of Strong Space-Charge Forces

We treat the case of an electron fluid with finite pressure embedded in a slowly varying axial magnetic field. Allowing for the presence of ions and accompanying space-charge forces, we find that variations in the resulting drift velocity vD alter the electron's precession frequency from the gyrofrequency Ω to a new frequency ω, with ω2 = Ω2 - Ω·(▿×vD). The precession orbit becomes distorted into an ellipse and the conventional adiabatic invariant is replaced with a new one. The fluid-dynamic consequences of these alterations are explored in the limit that the initial electron pressure is small compared to the initial magnetic pressure.