The Joint Accelerator Conferences Website (JACoW) is an international collaboration that publishes the proceedings of accelerator conferences held around the world.
TY - CONF AU - Du, B. AU - Huang, G. AU - Lin, L. AU - Liu, W. AU - Zhou, Z.R. ED - Schaa, Volker RW ED - Arduini, Gianluigi ED - Pranke, Juliana ED - Seidel, Mike ED - Lindroos, Mats TI - DSP Frame and Algorithm of LLRF of IR-FEL J2 - Proc. of IPAC2017, Copenhagen, Denmark, 14â19 May, 2017 C1 - Copenhagen, Denmark T2 - International Particle Accelerator Conference T3 - 8 LA - english AB - Infrared Free Electron Laser (IR-FEL) use linear accelerator to accelerate electron to relative speed and then generate simulated radiation of infrared wavelength by periodic magnetic field of undulator. The amplitude and phase of microwave field need to be controlled precisely by low level RF control system (LLRF) to meet the high quality demand of electron from undulator. This paper mainly introduce the digital signal processing frame and feedback algorithm. Four times frequency sampling can realize IQ demodulation precisely and reduce DC offset, amplitude sampling error is less than 0.075% and phase sampling error is less than 0.1°. Pipeline CORDIC can calculate amplitude and phase by parallel processing and shift operation. Phase calculating accuracy reach 0.0005° when iteration count is 18. FIR filter is used to improve frequency selected performance. Feedback loop use digital PI controller to adjust system output. PB - JACoW CP - Geneva, Switzerland SP - 4017 EP - 4019 KW - feedback KW - LLRF KW - FEL KW - controls KW - target DA - 2017/05 PY - 2017 SN - 978-3-95450-182-3 DO - 10.18429/JACoW-IPAC2017-THPAB124 UR - http://jacow.org/ipac2017/papers/thpab124.pdf ER -