TY - CPAPER AU - Niknejadi, P. AU - Madey, J. TI - Inclusion of Advanced Fields and Boundary Conditions in the Analytic Theory for High Gain FELs J2 - Proc. of FEL2015 AB - The efforts in realizing x-ray free electron lasers (FELs) and enhancing their performance has stimulated remarkable theoretical developments and experimental advances in the field. Yet, the successful operation of x-ray FELs based on the self-amplified spontaneous emission (SASE) principle which has made them a powerful new tool, has beckoned our attention for better understanding a comprehensive physical basis of the theory that has the potential to improve the temporal structure and spectral optimization of these sources. We have previously explained the advantages of including the coherent radiation reaction force as a part of the solution to the boundary value problem for FELs that radiate into "free space" (SASE FELs) and discussed how the advanced field of the absorber can interact with the radiating particles at the time of emission.(*, **) Here we present the outline of our theoretical approach which follows from eigenmode analysis of optical guiding in FELs. We will also discuss in some detail the experimental setup that could verify and/or further our understanding of the the underlying physics of these devices. PB - JACoW CY - Geneva, Switzerland SP - 735 EP - 738 KW - FEL KW - electron KW - radiation KW - target KW - undulator DA - 2015/12 PY - 2015 SN - 978-3-95450-134-2 DO - 10.18429/JACoW-FEL2015-WEP079 UR - http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/wep079.pdf ER -