Rogowski coil for hundreds-ps current pulses.

The technological evolution has affected accelerating machines, digital communication, electromagnetic pulse generators and many other devices and Rogowski coils are used for current diagnostics. In particular, for biophysical applications Rogowski coils are obtained both for linear structures and for the diagnostics of shorter and shorter pulses, $100 {ps}$. Many authors have studied the Rogowski coils but none have taken into account the influence of the slit applied in order to lead the unknown current. The slit forms a capacitor and an inductor both parasite, but the capacitor can be neglected. Applying the laws of electromagnetism and solving the problem by Laplace transforms, the size of the slit affects the attenuation factor. The output current increases as the slit width increase because of the total inductance decrease. Consequently, the attenuation factor decreases $vs.$ the slit width. Two different devices by plane lines were built for the study of the Cry protein. The approximate attenuation factors were 9.6 and $14.5 {A/V}$ and the rise time for both devices was of $250 {ps}$.