No abstract available

[en] A beam chopper is required in the transfer line between the 1 GeV/c TRIUMF cyclotron and the Accumulator ring of the pro-posed 30 GeV/c KAON Factory synchrotrons. The beam chopper must generate pulses with a magnitude of at l-t 9.5 kV, with rise and fall times of less than 38 ns, at a repetition rate of 10⁶ pulses per second, and at a 100% duty cycle. Precise control of grid timing aid voltage is required at the driver tetrode to achieve deflector kick pulse widths of 48 ns and 92 ns while maintaining an interpulse and flattop ripple at less than ±10% of the deflector kick magnitude. Results of measurements are presented where all of the design criteria have been met, for the first time, over a wide range of pulse widths with sub-nanosecond precision. Rise and fall times of 18 ns to 31 ns have been achieved on 15 kV pulses at 0.93 x 10⁶ pulses per second continuous operation. (author) 10 refs., 9 figs., 1 tab

[en] Kicker magnets will be required for all ring-to-ring transfers in the 5 accelerator rings of the KAON factory. The kick must rise (or fall) from 1% to 99% of full strength during the time interval of gaps created in the beam so that the beam can be extracted fully with minimum losses. The gaps in the beam will be created by a 1 MHz (10⁶ discrete pulses/s) beam chopper installed in the injection line to the Accumulator (A) ring. The repetition rate of the kicker magnets must be 50Hz in the A, and Booster (B) ring and for injection into the Collector (C) ring. The rate must be 10Hz in the Driver (D), and Extender (E) ring and for extraction from the C ring. Kicker magnet design parameters have been studied for various lattice designs. A total of 12 injection, 27 extraction and 10 diagnostic kicker magnet modules as well the 1 MHz chopper will be required. A summary of kicker parameters is presented. Results of tests on a prototype kicker magnet, which was built at TRIUMF, that was successfully operated at a repetition rate of 50Hz with a PFN voltage of 74kV, using an upgraded pulser that is on loan from CERN, are also presented. Results of extensive computer modelling are also summarized. (author)

[en] Deflection of 1 GeV/c H^- beam bunches to be eliminated by the 1 MHz chopper, for the proposed Kaon factory at TRIUMF, will be provided by an electric field between a set of deflector plates. Deflection rise time is a function of beam transit time through the deflector plates and the rise time of the stored voltage pulse. This paper presents the results of time-domain mathematical simulations to assess the relationship between the above quantities: the results of these simulations allow an accurate determination of the required rise-time of the stored voltage pulse. The representation of the deflector plates is modified so that linear displacement of the beam, as well as angular deflection, may be assessed. Simulations have also been performed to assess the attenuating effect of the deflector plates upon both angular deflection and linear displacement of the H^- beam caused by voltage ripple. A measured voltage pulse is simulated as driving the deflector plates, and beam deflection is predicted. (Author) 12 refs., 3 figs

[en] A pulse generator consisting of a coaxial cable and a high voltage modulator, incorporating two stacks of Field-Effect Transistor (FET) switches operating in ''push-pull'' mode, has been designed and built. The modulator generates a continuous, unipolar, pulse train at a fundamental frequency of 1 MHz and a magnitude of 10 kV. The rise and fall times of the pulses are less than 39 ns. The two stacks each utilize 14 FETS, which are individually rated at 1 kV. The design incorporates a low-loss coaxial cable on which pulses are stored. Extensive PSpice simulations have been carried out to evaluate various design options. Subsequent measurements on the prototype pulse generator confirm the PSpice predictions. This system is applicable for the kicker system at TRIUMF

[en] 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 in 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

[en] The field rise for kicker magnets is often specified between 1% and 99% of full strength. Three-gap thyratrons are frequently used as switches for kicker magnet systems. These thyratrons turn on in three stages: the collapse of voltage across one gap causes a displacement current to flow in the parasitic capacitance of off-state gap(s). The displacement current flows in the external circuit and can thus increase the effective rise-time of the field in the kicker magnet. One promising method of decreasing the effect of the displacement current involves the use of saturating ferrites. Another method for achieving the specified rise-time and 'flatness' for the kick strength is to utilize speed-up networks in the electrical circuit. Measurements have been carried out on a prototype kicker magnet with a speed-up network and various geometries of saturating ferrite. Measurements and PSpice calculations are presented. (author)

[en] Kicker magnets are required for all ring-to-ring transfers in the 5 rings of the proposed KAON factory synchrotron. The kick must rise/fall from 1% to 99% of full strength during the time interval of gaps created in the beam (80 ns to 160 ns) so that the beam can be extracted with minimum losses. Approximately one-third of the injection and extraction kicker magnets will operate continuously at a rate of 50 pulses per second: the others operate at 10 pulses per second. The kicker magnet PFN voltages will be in the range 50kV to 80kV, hence multi-gap thyratrons will be used for the injection and extraction kicker systems. Displacement current arising from turn-on of a multi-gap thyratron flows in the external circuit and can thus increase the effective rise-time of the kick. A mathematical model of a three-gap thyratron, which includes the drift spaces, has been developed for simulating turn-on, and is described in this paper. The thyratron model has been used to investigate ways to suppress the effects of displacement current on the kick, and to reduce thyratron switching loss. A ferrite saturating inductor may be connected adjacent to each thyratron to reduce switching loss, so that thyratron life can be extended and the kick rise-time improved. This inductor can also be used to reduce the effect of anode displacement current during turn-on of a multi-gap thyratron. The research has culminated in a predicted kick rise time (1% to 99%) of less than 50 ns for a TRIUMF 10 cell prototype kicker magnet. The proposed improvements are currently being implemented on our prototype kicker system. (author). 15 refs., 11 figs

[en] 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. (author)

[en] Kicker magnets are required for all ring-to-ring transfers in the 5 rings of the proposed KAON factory. The kick must rise from 1% to 99% of full strength during the time interval of gaps (80 ns to 160 ns) created in the beam so that beam extraction losses are minimized. The 'kick' strength must have a uniformity of ± l% over the useful aperture of the magnet. PE2D calculations have been performed to determine the uniformity of the combined electric and magnetic kick in the aperture of a TRIUMF prototype kicker magnet. Measurements of the magnetic field were performed with 50Ω striplines while the prototype magnet was excited with a low voltage 1 MHz sine wave. The predicted and measured results for the magnetic field in the prototype kicker magnet are in good agreement, and are presented in this paper. Circuit analysis code PSpice has been utilized to mathematically model the magnet and stripline probe, and the results of the simulations have provided a better understanding of the effect of parasitics upon the measurements. (author). 6 refs., 1 tab., 2 figs