The charge measurements system at PHIL, LAL
PHIL is an electron beam accelerator at LAL (Laboratoire de l Accelerateur Lineaire). It produce low energy (E<5 MeV) and high current (1nC/bunch) electrons bunch at a repetition frequency of 5Hz. The charge measurements are performed by two Integrated Current Transformers (ICT) and two Faraday's cup. Signals from the charge measurement system were displayed on an oscilloscope, and used to calculate the charge and dark current manually using the oscilloscope features. This operation is long, not accurate and cannot be integrated in the control command system. To overcome this problems, a new approach was adopted, based on two systems: 1) An electronic system to integrate the signal from the charge measurement systems (20ns large pulse), and outputs a large duration signal (around 400µs) whose amplitude is proportional to the beam charge. 2) A microcontroller that aquire the integrated signal with a repition rate of 5Hz, make the analog-digital conversion, and calculate the statistical values of the signal. Output signal can be sent to the control command system for displaying and to automate other process, especially the charge-RF phase measurements. This system is accurate, with a resolution of around 1pC, and can be easily integrated in the control command system.