Wave and particle measurements near the lower-hybrid frequency

Experimental results are presented on lower-hybrid waves excited in a plasma column by an electrostatic coupler. It is found that the observed wave patterns which clearly show resonance cones, are as predicted by a theory based on the superposition of bounded-plasma eigenmodes for a source with a wide kz spectrum and are also consistent with the WKB resonance-cone formulation. Results on electron heating and plasma loss produced by lower-hybrid waves are also presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48950/2/ppv19i5p455.pd

An experimental study of microwave stability near transition in the PSR

We have undertaken a study of microwave stability in the PSR storage ring under a variety of beam conditions near transition, including variable intensity and machine impedance, which can be independently controlled in the PSR. Results indicate that the general features of a linear stability model are valid, namely that the instability threshold becomes very small sufficiently close to transition. In addition, many nonlinear features are apparent and the results suggest an extended operating regime is possible with saturated, but otherwise benign, longitudinal fluctuations. Details of the linear model experimental results and corresponding simulations will be presented

A compact layout for a 50 GeV proton radiography facility

We describe a new compact layout for a 50 GeV proton radiography facility. The more compact design utilizes two-point extraction from the main ring to drive an optimal 8 view imaging system. The lattice design of both the main ring, and of the corresponding 8.5 GeV booster ring is described. The rings have very good longitudinal stability, which is of interest for other applications of high current proton machines in this energy range

Characterization of the proton beam at the output of the 6.7MeV LEDA RFQ.

The present configuration of the Low-Energy Demonstration Accelerator (LEDA) consists of a 75-keV proton injector, a 6.7-MeV 350-MHz cw radio-frequency quadrupole (RFQ) with associated high-power and lowlevel rf systems, a 52-magnet periodic lattice followed by a short high-energy beam transport (HEBT) and highpower (670-kW cw) beam stop. The rms beam emittance was measured prior to the installation of the 52-magnet lattice, based on wire-scanner measurements of the beam profile at a single location in the HEBT. New measurements with additional diagnostic hardware have been performed to determine the rms transverse beam properties of the beam at the output of the 6.7-MeV LEDA RFQ. The 52-magnet periodic lattice also includes ten beam position monitors (BPMs) evenly spaced in pairs of two. The BPMs provide a measure of the bunched beam current that exhibits nulls at different locations in the lattice. Model predictions of the locations of the nulls and the strength of the bunched beam current are made to determine what information this data can provide regarding the longitudinal beam emittance

The Sloan Digital Sky Survey: Technical Summary

The Sloan Digital Sky Survey (SDSS) will provide the data to support detailed investigations of the distribution of luminous and non- luminous matter in the Universe: a photometrically and astrometrically calibrated digital imaging survey of pi steradians above about Galactic latitude 30 degrees in five broad optical bands to a depth of g' about 23 magnitudes, and a spectroscopic survey of the approximately one million brightest galaxies and 10^5 brightest quasars found in the photometric object catalog produced by the imaging survey. This paper summarizes the observational parameters and data products of the SDSS, and serves as an introduction to extensive technical on-line documentation.Comment: 9 pages, 7 figures, AAS Latex. To appear in AJ, Sept 200