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Free-Electron Lasers
Chapter 18
18. Free-Electron Lasers
Michelle Shinn
18.1 Introduction to Free-Electron Lasers
e lasers discussed so far in this book are based on bound electron systems. It is also
possible to have laser action using an ensemble of free electrons. At rst blush, elementary
quantum mechanics would lead one to think that since a free electron has a continuous
set of energy levels to choose from, there is no upper or lower energy level to transition
between. However, as shown in [1], it is possible to create such a pair of states. What is
notionally correct, based on elementary quantum theory, is that one can set the tra