Thermally excited fluctuations as a pure electron plasma temperature diagnostic

Thermally excited charge fluctuations in pure electron plasma columns provide a diagnostic for the plasma temperature over a range of 0.05 0.2, so that Landau damping is dominant and well modeled by theory. The third method compares the total (frequency-integrated) number delta N of fluctuating image charges on the wall antenna to a simple thermodynamic calculation. This method works when lambda(D)/R-p > 0.2

Thermally excited Trivelpiece–Gould modes as a pure electron plasma temperature diagnostic

Thermally excited plasma modes are observed in trapped, near-thermal-equilibrium pure electron plasmas over a temperature range of 0.05<kT<5 eV. The modes are excited and damped by thermal fluctuations in both the plasma and the receiver electronics. The thermal emission spectra together with a plasma-antenna coupling coefficient calibration uniquely determine the plasma (and load) temperature. This calibration is obtained from the mode spectra themselves when the receiver-generated noise absorption is measurable; or from separate wave reflection/absorption measurements; or from kinetic theory. This nondestructive temperature diagnostic agrees well with standard diagnostics, and may be useful for expensive species such as antimatter

Collective modes and correlations in one-component plasmas

The static and time-dependent potential and surface charge correlations in a plasma with a boundary are computed for different shapes of the boundary. The case of a spheroidal or spherical one-component plasma is studied in detail because experimental results are available for such systems. Also, since there is some knowlegde both experimental and theoretical about the electrostatic collective modes of these plasmas, the time-dependent correlations are computed using a method involving these modes.Comment: 20 pages, plain TeX, submitted to Phys. Rev.

Voting on Growth Control Measures: Preferences and Strategies

Citizens of many California cities and counties have sought to restrict the rate of population growth in their localities. In 1988, Citizens for Limited Growth used the initiative process to place a pair of growth control measures on the ballot in the City and County of San Diego, respectively. The City Council and Board of Supervisors responded by placing less stringent, competing measures on the same ballot. This paper analyzes voting data from this election to examine the nature of support for such measures. We find strong support for the hypotheses that whites, homeowners, liberal/environmentalists, and those exposed to high levels of traffic congestion are more likely to favor growth controls. This paper also investigates the behavior of voters when they confront competing propositions concerning the same issue on the same ballot, and finds strong evidence of strategic voting

Confining Bethe--Salpeter equation in QCD

We derive a confining $q \bar{q}$ Bethe--Salpeter equation starting from the same assumptions on the Wilson loop integral already adopted in the derivation of a semirelativistic heavy quark potential. We show that, by standard approximations, an effective meson squared mass operator can be obtained from our BS kernel and that, from this, by ${1\over m^2}$ expansion, the corresponding Wilson loop potential is recovered, spin--dependent and velocity--dependent terms included. We also show, that, on the contrary, neglecting spin--dependent terms, relativistic flux tube model is reproduced.Comment: 5 pages, Latex, talk given at the workshop CONFINEMENT95, 22-24 March, Osak

Polarization-correlated photon pairs from a single ion

In the fluorescence light of a single atom, the probability for emission of a photon with certain polarization depends on the polarization of the photon emitted immediately before it. Here correlations of such kind are investigated with a single trapped calcium ion by means of second order correlation functions. A theoretical model is developed and fitted to the experimental data, which show 91% probability for the emission of polarization-correlated photon pairs within 24 ns.Comment: 8 pages, 9 figure

Bethe--Salpeter equation in QCD

We extend to regular QCD the derivation of a confining $q \bar{q}$ Bethe--Salpeter equation previously given for the simplest model of scalar QCD in which quarks are treated as spinless particles. We start from the same assumptions on the Wilson loop integral already adopted in the derivation of a semirelativistic heavy quark potential. We show that, by standard approximations, an effective meson squared mass operator can be obtained from our BS kernel and that, from this, by ${1\over m^2}$ expansion the corresponding Wilson loop potential can be reobtained, spin--dependent and velocity--dependent terms included. We also show that, on the contrary, neglecting spin--dependent terms, relativistic flux tube model is reproduced.Comment: 23 pages, revte

Star clusters dynamics in a laboratory: electrons in an ultracold plasma

Electrons in a spherical ultracold quasineutral plasma at temperature in the Kelvin range can be created by laser excitation of an ultra-cold laser cooled atomic cloud. The dynamical behavior of the electrons is similar to the one described by conventional models of stars clusters dynamics. The single mass component, the spherical symmetry and no stars evolution are here accurate assumptions. The analog of binary stars formations in the cluster case is three-body recombination in Rydberg atoms in the plasma case with the same Heggie's law: soft binaries get softer and hard binaries get harder. We demonstrate that the evolution of such an ultracold plasma is dominated by Fokker-Planck kinetics equations formally identical to the ones controlling the evolution of a stars cluster. The Virial theorem leads to a link between the plasma temperature and the ions and electrons numbers. The Fokker-Planck equation is approximate using gaseous and fluid models. We found that the electrons are in a Kramers-Michie-King's type quasi-equilibrium distribution as stars in clusters. Knowing the electron distribution and using forced fast electron extraction we are able to determine the plasma temperature knowing the trapping potential depth.Comment: Submitted to MNRA