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ISIS Beam Protection System and MICE operation.

ISIS Beam Protection System and MICE operation. Dean Adams 29 Nov 07 Presented by Chris Rogers. ISIS Beam Protection System.

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ISIS Beam Protection System and MICE operation.

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  1. ISIS Beam Protection System and MICE operation. Dean Adams 29 Nov 07 Presented by Chris Rogers

  2. ISIS Beam Protection System • ISIS Beam Protection System (BPS) consists of hardware interlocks (magnets, RF..) and beam diagnostic measurements (Intensity and Beam loss monitors). The latter using DAQ and tolerance comparison to determine trips. • To minimise beam off time an ‘inhibit unit’ sits above the BPS system and turns the beam off on a BPS trip for ~ 1.5 s and then automatically switches the beam back on. If another BPS trip occurs within 10s then the beam is switched off by insertion of a beam stop. This then requires a manual reset to enable beam.

  3. Beam Intensity Monitors • 1 Current transformer (R5IM1) sits in SP5. • DAQ resolution 2e10 protons per pulse. • Acceleration tolerances 2.5 – 9.8 ms • BPS trip : 3 consecutive > 2e12 each 25 consecutive > 0.5e12 average/pulse • BPS warning displayed in ISIS MCR @ 30 s and 20 mins if average per pulse > 0.25e12 or 0.2e12

  4. Beam Loss Monitors • 39 BLM’s in ring. • Each BLM signal is integrated 0-10 ms and compared to a tolerance. • Trip issued when 20 pulses > tolerance in 15 MINUTES. • Pulse count reset on each trip. • BLM upgrade Jan 08. Pulse count changed to 20 CONSECUTIVE pulses.

  5. MICE operation and the current ISIS BPS • Assumptions: MICE at 1 Hz, ISIS at 50 Hz. • Intensity Monitors 3 consecutive pulses : MICE cannot force this trip alone. 25 pulse average : MICE could produce one BPS trip if it intercepted more than 25* 0.5e12 = 1.25e13. This would produce an inhibit. The next MICE dip occurs in less than the 10s inhibit window so additional loss would cause another trip and turn the machine off. • Beam Loss Monitors 20 pulses in 15 mins : MICE can inhibit but never trip 20 consecutive pulses: MICE cant inhibit or trip.

  6. Where to go next. • Old HEP target operated @50 Hz diping at 7 ms for ~ 200 µs. ISIS BLM tolerances were 0.2 V in super period 7. MICE target @1Hz but dips from 8-10 ms. Different machine activation source. Need to quantify.. • Current BPS protection not suitable for MICE. ISIS will need to produce some new trip mechanism on the BLM’s. Ie DAQ system measuring SP7 losses at 1 Hz connected to ISIS BPS system. • Target tests in Jan 08 should limit loss to 0.05 V trip level. During this time machine activation can be measured. The requirement for MICE rates and ISIS activation can then be reviewed.

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