BEAM CURRENT TRANSFORMER WITH DC TO 200-MHz RANGE.

Abstract

Beam currents in particle accelerators are commonly measured by passing them through the center hole of a toroidal transfonner.By de finition, the response is limited to a.c.com ponents of the signal.The paper describes a combination of ma gnetic modulator and active L/R integrator in a common feedback loop whereby a current trans former with flat frequency response dcwn to zero frequency is obtained.The scheme is ana logous to the well known chopper stabilj zed d. c. amplifier and offers high accuracy and sen sitivity, together with a large dynamic rangC and good zero stability.The full frcqt:.c:ncyrange from d. c. to more than 200 MHz is acCieved by adding to this ar rangement a fast passive current trar.sformer with composite core and active back-up loop.