MX-BPM

Multi-pass or CW beam position measurement

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Multi-pass or CW beam position measurement

Principle

The signals from the four button electrodes are fed into the BPM module. The module processes the signals sequentially to give 3 analog output voltages: X, Y and Sum.

The four signals are multiplexed by four GaAs switches. The switches close one at a time under the control of a local clock, sampling each button 2000 times per second.

An external clock signal can override this onboard clock, to sample every button up to 10 000 times per second. The outputs of the four switches give a sequential signal. A low-noise preamplifier amplifies the signal under automatic gain control.

Only additions and subtractions are needed to obtain the X and Y positions, because the sum of all four buttons is normalized at all times to a constant value.

Main features

  • Resolution X & Y 1 µm
  • Dynamic Range > 75 dB
  • Operating Frequency From 60 MHz to 500 MHz

Features

  • The Beam Position Monitor (BPM) is an all-analog electronics module with superior performance in a very small volume
  • GaAs switches provide superior button-to-button isolation and low insertion loss
  • Automatic Gain Control range >90dB provides optimum level for demodulator, independent of beam intensity, number of bunches
  • Phase-locked synchronous demodulation gives high linearity and noise suppression
  • Button signal range –70dBm…+5dBm at selected harmonic
  • X / Y output ±10V, 0V for on-center beam