Integrating Current Transformer & Beam Charge Monitor

Integrates bunch down to femtoseconds.

ICT integrates bunch charge without loss For transfer lines, injection/extraction monitoring and For laser-plasma, wakefield accelerators.


Single very short bunches, down to femtoseconds are integrated without loss. Microsecond long trains of very short micro bunches are integrated with negligible loss. High sensitivity for pC resolution pulse measurement.



ICT combines two nested transformers:

A shorted one-turn current transformer loads the bunch charge in a series of low-inductance capacitors distributed evenly around the transformer toroid. The full bunch charge is instantly loaded in those capacitors. A readout transformer transfers the charge loaded in the capacitor to its readout winding, at a slow pace determined by the RC time constant loading the winding. As a result of this very low frequency transfer, the eddy-current losses in the cores are negligible. Alloys used to assemble these cores are specially annealed to lower their coercive field and further minimize core loss.


In-flange ICT are mounted directly in the beam line. UHV compatible. Available for many pipe diameters: 1", 1.5", 2.5", 4", 6" and 8" Also with elliptical aperture or other arbitrary shape aperture. Ceramic gap, shields and wall current bypass are included. Bellows are not required.


In-air ICT are installed over the vacuum chamber. It requires a "gap" in the vacuum chamber to prevent the wall current from flowing through the ICT aperture. The gap can be a brazed ceramic ring or an organic material O-ring depending on the vacuum requirements. Typical installations include bellows, a wall current bypass and an electromagnetic shield covering the ICT completely.Schema ICT


The Beam Charge Monitor (BCM) measures the beam charge of pulsed beams.


BCM processes the signal from an Integrating Current Transformer (ICT). It has a bipolar voltage output that is directly proportional to the beam charge. The ICT integrates the charge of either single micropulses or macropulses made of many micropulses. Micropulses width can be shorter than a picosecond to longer than a microsecond. Even so short pulses are faithfully integrated with high linearity and absolute accuracy.
Specially developed hybrid circuits then amplifly the charge and integrate it with low noise and high linearity. A built-in Calibration Generator provides on-line assurance of measurement reliability.