Particle Charging in DC Corona Fields
After a brief review of the currently accepted theory of particle charging in corona fields in air by both ionic bombardment and diffusion in the dark space surrounding the dc corona glow, the paper presents some of the recently published findings on particle charging within the corona glow. The study was made possible by the discovery that additions of CO2 to air in a 5 to 20% range will increase a cylindrical positive corona glow to a size which is sufficiently large to allow particles to be dropped on to various trajectories parallel to the corona wire and their charge to be measured. The influence of the shape of the particles when exposed to corona charging is also discussed.
Charging of Polar Versus Nonpolar Liquids During Brief Exposure to Ionic Currents
Experimental results are reported which show the amount of corona charging of polar and nonpolar liquid droplets during brief exposure to ionic currents. They show that the nonpolar materials tested acquired from 10 to 36 percent less charge than equivalent water droplets and that the polar materials acquired from 1 to 15 percent more charge than the water. These differences are not predicted by the Pauthenier theory. The reason for the differences is believed to be due to the relaxation time of the materials and the effect it has on the rate at which the ionic particles may distribute themselves over the surface of the droplet. In particular, the nonpolar materials being highly resistive have long relaxation times and thus acquire fewer charges than the polar materials.
Parameters for low energy operation of CESR
We present a detailed design for operation of the Cornell Electron Storage Ring, CESR, in the energy range covering the /spl psi/ resonances and the Charm and Tau thresholds, as well as reaching to the upper Y resonances near 11 GeV. The addition of 18 m of super-ferric wiggler magnets will partially restore low energy beam emittance and damping times. Installation of superconducting quadrupoles in the interaction region and the addition of high performance superconducting RF cavities will enhance performance at all energies. Studies of optics, beam dynamics, wiggler and vacuum system performance, beam stability, and beam-beam effects confirm operation with a luminosity of 3/spl times/ 10/sup 32/ CM/sup -2/ sec/sup -1/ at 1.88 GeV.