Design, simulation and test of pulsed Panofsky quadrupoles

Abstract

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.

The Maryland electron ring for investigating space-charge dominated beams in a circular fodo system

“…The electron bunch is injected into the ring at a repetition rate of 60 Hz or less from the injector system [3] with the help of two pulsed Panofsky quads [6] and a pulsed dipole. The bunch can be extracted within the first turn or after any number of turns with a system that duplicates the features of the injector line except that the electron gun is replaced by a large diagnostic chamber with phosphor screen, emittance meter and energy analyzer.…”

PIC code simulations of collective effects in the space-charge-dominated beam of the University of Maryland Electron Ring (UMER)

“…The code has played a role in designing the injector [9], especially the inflector bend, and in testing the effects of the Panofsky quad used in injection [10]. The simulations have reproduced radial density waves observed in a prototype injector experiment [4], and played a major role in linking this phenomena to the initial particle distribution at the aperture.…”

The 10 keV injector for the University of Maryland Electron Ring Project

“…With a circulation time of 200 ns, the bunch length is expected to be 50-75 ns. The rise and fall time of the pulsed elements is expected be ~30 ns [2]. Since the two Panofsky quadrupoles overlap slightly, the mutual interaction is of some concern and is being studied with bench models.…”

“…The injector consists of an electron gun, means for matching the beam into a quadrupole lattice, and pulsed elements for injecting the beam into the ring. The pulsed elements include a pulsed dipole and two Panofsky quadrupoles, one for the injected beam and the other for the recirculating beam [2].…”