BL1U at TRIUMF UCN Beamline Kicker Magnet (April 12, 2010)

UCN Facility in Meson Hall 12 mr 145 mr 18.5  deflection: KICKER

Kicker Specs:  500 MeV protons (p = 1090 MeV/c)  15 mr maximum deflection (Bdl = Tm); normal deflection 12mr  effective length 1.5 m (physical available 2 m)  aperture 100 mm x 100 mm (under review)  field uniform to  5% over central 80 mm diameter region  flat top 1 ms, flat to  5% over the 1 ms  fires every 3 ms (330 Hz rep. rate, able to run continuously)  can be re-configured (in <1 hr) to run as low as 100 Hz (33 Hz) rep rate  power supply able to be located 10 m away Notes: The aperture is an important constraint. Reducing the vertical aperture reduces the current needed for a given deflection (or reduces the length of the magnet). Decreasing the horizontal aperture decreases the inductance, and hence the voltage needed for ramp-up and ramp-down. The rise time is also important. The high voltage needed for ramp up and down scales as 1/T rise The trade-off between the different parameters is shown in the next two slides.

7 mm 60 mm 100 mm  “Two Sigma” beam spot containing 90% of beam is 16 mm wide by 5.5 mm high  Beam moves ~8mm horizontally at exit of kicker when kicker fires  Beam would still be 8.8 sigma from wall  Smaller horizontal dimension reduces inductance and hence power supply voltage  Smaller vertical dimension reduces the magnet length or the power supply current  It’s important not to make the aperture larger than necessary Ceramic pipe How small can the aperture be?

Proposed time division of beam 50  s to 100  s 2/3 beam to  SR 1/3 beam to UCN normal TRIUMF beam, 4 min ms 2 ms 1 ms 1 min. 120  A

Example of Proton Beam Sharing  A 80  A 40  A 120  A 0  A 1 min.4 min. meson hall UCN source

Preliminary Coil Design for UCN Kicker Mike Barnes

UCN Kicker Mike Barnes Aluminum Ferrite Air

Kicker Power Supply

Ramp-Up: SW1 and SW2 are closed, magnet ramps up from the high voltage + -

Kicker Power Supply End of Ramp-Up: + - SW1 is opened. Current circulates through D3, D1, and SW2

Kicker Power Supply Flat Top: + - SW3 closes as required to maintain the flattop with the low voltage supply + -

Kicker Power Supply Ramp-Down: + - All switches open. Current is against the HV for fast ramp down. Stops at I=0 when diodes become back biased.

rise/fall time (  s) Turns (N) inductance (  H) flattop current peak voltage A4500 V A2900 V A2500 V A1300 V A1700 V A1900 V Examples: This table shows some examples of what could be done for a 100 mm x 100 mm aperture. As the rise/fall time gets longer the required peak voltage goes down (all else being equal). For a fixed rise/fall time, the current scales as 1/N and the peak voltage as N. By adjusting N, we can trade current against voltage. The most likely choices are highlighted (Numbers are rounded off)

Kicker Aperture - Reducing Kicker Aperture sizes (Vert. & Horiz.) reduces the supply current & voltage requirements  reduces P.S. costs - Limiting factor  beam halo Coil Lifecycle - Kicker repeatedly going ON/OFF  Mechanical stresses? - Limit to the total number of cycles the coils can go thru? - Spares recommended (M.Barnes recommends incl. spare coils) - Extend the lifecycle by changing Kicker rep-rate & flat-top? Kicker Failure Modes - Need to quantify the nature & frequency of kicker failure modes Issues: