The University of Maryland Electron Ring (UMER), currently under construction, has been designed to study the physics of space-charge dominated beams at extremely large values of the betatron tune shift which exceed those of existing strong-focusing synchrotrons and rings by more than an order of magnitude. In this paper, the unique design features of this research facility, the new beam physics to be investigated, and recent experimental results in the injector prototype as well as simulation studies will be reviewed.

Results are presented for electron beam transport experiments in a 1-m-long straight section consisting of a solenoid and five short printed-circuit quadrupoles. A linear computer code for rms envelope matching, SPOT, is used for channel design, while final simulations with more realistic elements are obtained with a 2 1 2 D version of WARP, a particle-in-cell code. Reasonable agreement is found between calculations and the effective beam envelope obtained from pictures of the beam on a movable phosphor screen. The results validate, within experimental errors, the use of short magnetic quadrupoles for the transport of space-charge dominated beams. The straight section constitutes the prototype matching section for an electron recirculator to be built at the University of Maryland. [S1098-4402(98)

Two Panofsky quadrupoles with rectangular aperture and fast rise time are proposed for the injection area in the University of Maryland electron ring project (UMER) [1,2,3]. The theoretical current distribution needed on the surface of a rectangular aperture to produce a quadrupole field is derived [4]. The conductor location is determined mostly by the theoretical current distribution, with some free factors to optimise the field. The design is based on the linearity of longitudinal integrated field. Each quadrant of the Panofsky quadrupole consists of 10 loops of conductors to minimize inductance while retaining the field quality. A 2:1 scaled model has been made and the magnetic field was measured. Two 1:1 models have been made to measure inductance, mutual inductance and the rise time. Simulations of beam propagation with Panofsky quadrupoles demonstrated the linearity of the design.

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The 10 keV, 100 mA, Pierce-type electron gun and injector for the University of Maryland Electron Ring (UMER) Project are described. Using a pulsed control grid located 0.15 mm from the 4-mm radius cathode, 100ns bunches are generated. The A/K gap is variable, producing beam currents ranging from 50 to 160 mA. A rotatable aperture plate is included to allow six different masks, including a pepperpot. Beam current after the aperture plate is measured with a built-in Rogowski coil. The injector line consists of a solenoid lens, five printedcircuit quadrupoles, and two in-line diagnostic chambers. A separate, multi-purpose chamber is placed at the end of the injector line during gun characterization studies for emittance, profile, and energy analysis.