Velocity Distribution of $\hbox{H}^{-}$ Ions in Low Temperature Hydrogen Plasma
A Monte Carlo solution of the Boltzmann equation is applied to the calculation of the velocity distribution of negative atomic ions H- in uniform H/H2 plasmas in a wide parameter range. Results are shown for the energy distribution n(epsiv), the 2-D velocity distribution, and the energy-dependent coefficients of the spherical harmonics expansion of its angular part, for different values of the reduced electric field E/N, the atomic fraction, and the H+ mole fraction. By increasing E/N or the atomic fraction at constant ion energy, the velocity distribution becomes highly anisotropic, and at same time, n(epsiv) features a suprathermal tail consistent with analytical results.
Modeling of Capacitively Coupled RF Plasmas in H2
Hydrogen is the main component of many feeding mixtures used for plasma processing. Despite this, the physics and chemistries of the parallel plate, capacitively coupled, radio frequency discharges in pure hydrogen are not yet fully understood. The state of the art of the modeling of this system is analyzed, including the problems posed by the electron and ion reactions, the ion heating, the chemistry of excited molecules, the non-equilibrium distributions, the surface catalytic reactions, the double frequency discharge effects. Specific points are illustrated using new results obtained by a self-consistent kinetic model developed in the last 10 years. A concluding discussion summarizes the achievements and open problems of the field.
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.