Using a pulsed deflector for extraction of pulsed beams from the TRIUMF cyclotron
In the normal mode of operation, the TRIUMF cyclotron accelerates H/sup -/ ions to produce 500 MeV proton beams of 160 /spl mu/A with 4 nsec pulses separated by 43 nsec. A proposed experiment (/spl mu//spl rarr/e conversion) requires a 500 MeV beam with 100-200 nsec pulses separated by 1-2 /spl mu/ sec with an average intensity of 200 /spl mu/A. Two methods have been investigated to achieve this time structure. Both incorporate a pulsed electric deflector and take advantage of extraction by stripping. In the first case, a deflector with a thin septum deflects radially up to six accumulated turns onto a stripping foil in one turn. In the second, a pair of vertically deflecting plates are pulsed at a frequency to excite a coherent vertical growth, and the particles are eventually intercepted by a stripping foil. Under certain conditions extraction occurs in almost perfect synchronism with the driving pulse. Both methods will be described in detail and results of computer simulations will be presented.
Measurements on a FET based 1 MHz, 10 kV pulse generator
A prototype pulser, which incorporates thirty-two 1 kV field-effect transistor (FET) modules, has been built and tested at TRIUMF. The pulser has been developed for application in a scheme for pulsed extraction from the TRIUMF 500 MeV cyclotron. Deflection of the beam will be provided by an electric field between a set of 1 m long deflector plates. The pulser generates a continuous, unipolar, pulse train at a fundamental frequency of approximately 1 MHz and a magnitude of 10 kV. The pulses have 38 ns rise and fall times and are stored on a low-loss coaxial cable which interconnects the pulse generator and the deflector plates. The circuit performance was evaluated with the aid of PSpice in the design stage and confirmed by measurements on the prototype. Temperature measurements have been performed on 1 kV FET modules under DC conditions and compared with temperatures under operating conditions to ensure that switching losses are acceptable. Results of various measurements are presented and compared with simulations.
PULSE: a high-repetition-rate linac driver for x-ray FELs
We describe a staged concept for a linac-based freeelectron laser providing coherent tuneable VUV and soft X-ray output with pulse lengths down to 10 fs or less. Use of 1.3 GHz cryomodules operated with CW RF will allow flexible pulse patterns at potentially very high repetition rates up to 1 MHz. We consider the options for FELs that may be included in a facility of this type.