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Beam Current Monitors Lunch-Time Seminar

Beam Current Monitors Lunch-Time Seminar. Martin Kesselman April 12, 2001. WHAT DO WE WANT TO MEASURE?. Number of charged particles in the beam A non-destructive measurement Measure current Number of charged particles per unit time Integrate over total beam pulse to get total charge. S.

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Beam Current Monitors Lunch-Time Seminar

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  1. Beam Current MonitorsLunch-Time Seminar Martin Kesselman April 12, 2001 BCM Lunchtime Seminar

  2. WHAT DO WE WANT TO MEASURE? • Number of charged particles in the beam • A non-destructive measurement • Measure current • Number of charged particles per unit time • Integrate over total beam pulse to get total charge BCM Lunchtime Seminar

  3. S N + + N S BASICS - Fields & Forces v MOVING CHARGE MAGNETS CHARGE BCM Lunchtime Seminar

  4. CURRENT MEASURING INSTRUMENTS • Faraday Cup • Wall Current Monitor • Beam Position Monitor • Current Transformer • Others BCM Lunchtime Seminar

  5. Faraday Cup - Simplified + BCM Lunchtime Seminar

  6. Wall Current Monitor - Simplified Volt Meter BCM Lunchtime Seminar

  7. Beam Position Monitor - Simplified Zo BCM Lunchtime Seminar

  8. Beam Position Monitor - Simplified R Zo - - - - - -- - Zo Iwall Reflection ++++++++ - - - - - - Ibeam + - - - - - - - ++++++++ Zo - - - - - - - Zo R BCM Lunchtime Seminar

  9. BASIC CURRENT TRANSFORMER Magnetic Field R N turns v Toroidal Core  is proportional to I I out is 1/N times I in Varying Current BCM Lunchtime Seminar

  10. Placing Transformer Inside the Beam Pipe Shroud Transformer Connected to pipe Connected to pipe Beam Pipe Ceramic Gap Vacuum Seal BCM Lunchtime Seminar

  11. BCM Testing Fixture BCM Lunchtime Seminar

  12. Large Testing Fixture BCM Lunchtime Seminar

  13. 220mm Inside Diameter Current Transformer BCM Lunchtime Seminar

  14. Example Transformer BCM Lunchtime Seminar

  15. SNS Ring Beam Current Readout BCM Lunchtime Seminar

  16. Short Rise Time- Long Decay Time LOW PASS Rise Time  HIGH PASS Droop  BAND PASS  BCM Lunchtime Seminar

  17. Droop in Current Transformer Signals BCM Lunchtime Seminar

  18. Compensating for Droop BCM Lunchtime Seminar

  19. HEBT Beam Instrumentation BCM Lunchtime Seminar

  20. SNS Ring Instrumentation BCM Lunchtime Seminar

  21. RTBT Beam Instrumentation BCM Lunchtime Seminar

  22. Beam Current Monitor Distribution * not finalized BCM Lunchtime Seminar

  23. 8 Bits + ADC DAC +0dB - Analog Front End & Digitizer Block Diagram AD602A or AD603 -10dB to +30dB AD8131 Diff. Out 1:100 15mA to 60 Amps SWITCHED ATTENUATOR 0dB,-20dB,-40dB 7MHz Gaussian LP Filter Dual-amps switched 0.12 V for 15mA 0.47V for 60mA 0.47V for 60A 78 Ohms FILTER -40 dB 6mV to 23.4 V -34dB to +26dB Duplicated for switched amps 8 Bits FRONT END GAIN REG. 1.05MHz rf AD6644 14 Bit +/- 1.1V 14 Bits DIGITAL INTERFACE DATA 40MHz or 60MHz Clock (continuous) DIGITIZER BCM Lunchtime Seminar

  24. DATA Partitioning Options Separate Boards SETTING INFO SETTING INFO Gain, Ref., etc. Gain, Ref., etc. TIMING REFERENCES 60MHz Sampling Clock RING Ref., etc. DIGITAL INTERFACE Averaging, Circular Buffer, Gain Memory, Gain Correction, Baseline Restore, Integration, Time-stamp ANALOG FRONT END and BAND-LIMITING SENSOR DIGITIZER DIFFERENTIAL INPUT DIFFERENTIAL INPUT STATUS STATUS BCM Lunchtime Seminar Digitizer with Analog Front End Digitizer with Interface

  25. 14 Bits Digital Interface 1.05MHz RING Ref 1.05MHz (f) RING Ref. PLL and TIMING TIMING EVENT TRIGGER 1mS GATE 67MHz Clock Gate Control Timing Data Timing In Data Timing Out DIGITIZER CIRCULAR DATA MEMORY FIFO DATA DATA DATA LOCAL COMPUTER PC INTERFACE 8 Bits GAIN & SETTINGS MEMORY BCM Lunchtime Seminar

  26. Information to Controls • All data time-stamped • Average Current/Charge per macro-pulse • Average Current/Charge per Mini-pulse • Time history for a macro-pulse • Time history for a single mini-pulse • Mode Information • Gain selection • Event markers • Ring Revolution rate • High speed digitizer capability BCM Lunchtime Seminar

  27. Iin/n Broadband Model 2=(RL/ RL+ Rs)((RsC/Le + (1/ RL)Le/C) o=1/(RL/ RL+ Rs) LeC Iin/n Low to Midband Model Simplified Equivalent Circuit BCM Lunchtime Seminar

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