Richard D'Arcy

Abstract:

The H- ion source and beam-line at FETS will require the beam current and beam position to be continually monitored. Current transformer toroids will measure the beam current and beam position monitors (BPMs) will determine the beam position. The ion source delivers pulses at a rate of 50 Hz with a current up to 60 mA, each pulse is 2 ms long, and a 324 MHz micro-bunch structure imposed by the radio frequency quadrupole (RFQ) accelerating structure. The toroid outputs will be acquired on a fast oscilloscope. Two BPM designs are under consideration (shorted strip-line or button type) but the processing for both types is similar and has been designed, with simulated measurements made. Each BPM uses four pickups, at a frequency of 324 MHz, which are mixed using RF electronics to an intermediate frequency of 10.125 MHz. The resulting signals are then digitized at 40.500 MHz and processed in an FPGA to produce the position and phase of the beam at each BPM location, with a precision of better than 100 μm and 0.05 rad. The measurements from the toroids and BPMs will be available via EPICS servers at every pulse.

Abstract:

EMMA (Electron Machine with Many Applications) is a prototype non-scaling Fixed-Field Alternating Gradient (ns-FFAG) accelerator whose construction at Daresbury Laboratory, UK, was completed in the autumn of 2010. The energy recovery linac ALICE [1] will serve as an injector for EMMA, within an energy range of 10 to 20 MeV. The injection line consists of a symmetric 30o dogleg to extract the beam from ALICE, a matching section and a tomography section for transverse emittance measurements. This is followed by a transport section to the injection point of the EMMA ring. The ring is composed of 42 cells, each containing one focusing and one defocusing quadrupole. Commissioning of the EMMA ring started in late 2010. A number of different injection energy and bunch charge configurations are planned; for some the effects of spacecharge may be significant. It is therefore necessary to model the electron beam transport in the injection line and ring using a code capable of both calculating the effect of and compensating for space-charge. Therefore the General Particle Tracer (GPT) code [2] has been used. A range of injection beam parameters have been modelled for comparison with experimental results. Copyright © 2012 by IEEE.

Abstract:

EMMA (Electron Model for Many Applications) is a prototype non-scaling electron FFAGoperating at Daresbury Laboratory. After demonstrating serpentine channel acceleration andfast resonance crossing in 2011, studies continue of the beam dynamics to explore the largetransverse and longitudinal acceptance, the detailed effects of integer tune crossing atslow acceleration rates, comparison of measurements to detailed field measurements, and theexperimental mapping of the machine by relating the initial and final phase spacecoordinates. These recent results are reported in this paper, together with more practicalimprovements such as injection orbit matching with real-time monitoring of the bunchcoordinates in transverse phase space. Copyright © 2012 by IEEE.