Most recently, a real-time interferometer (RTI) developed by Radiabeam to monitor the bunch length of high-current electron beams in an accelerator was tested. The RTI employs spatial autocorrelation, reflective optics, and a fast response pyro-detector array to obtain a real-time autocorrelation trace of the coherent radiation from an electron beam, thus providing the possibility of online bunch-length diagnostics. A complete RTI system was commissioned at the A0 photoinjector facility to measure sub-mm bunches at 13 MeV. Bunch length variation (FWHM) between 0.8 ps (~0.24 mm) and 1.5 ps (~0.45 mm) has been measured and compared with a Martin-Puplett interferometer and a streak camera. The comparisons demonstrated that the RTI is a viable, complementary bunch length diagnostic for sub-mm high-current electron bunches [21]. An example of measurement appears in Figure 7. References

In this article, we present the magnetic modeling of a batchfabrication process to imprint microscale pole patterns in hardmagnetic thick films. The imprinting process enables the creation of complex magnetic field patterns from permanent magnetic layers. The selective magnetic imprinting and the resultant stray fields are modeled in a two-step process using COMSOL Multiphysics in conjunction with measured magnetic hysteresis behavior. The models are used to evaluate the process design space and to predict the resulting stray magnetic field distribution in a patterned, 10-µm-thick Co-Pt magnetic film.