Conservation of brightness in undulator beamlines: Tangent errors and their reduction

Creating and conserving the high brightness of undulator light sources on storage rings of the third generation requires an optimization of (a) undulator design and operation, (b) beamline design, and (c) cooling schemes to minimize the effect of the photons absorbed in the optical components on the performance of those components. For storage rings with electron energies of 1.5–2 GeV, the problems associated with conservation of brightness through the entire system to and including the experiment are surmountable. In the present work the optimization details to points (a) and (b) above as presented in a previous work are summarized, and point (c) is developed in some detail. With the help of the finite element method (FEM) cooling schemes were investigated that minimize the loss of brightness resulting from the heat loading of the optical components. A new concept for external cooling that fulfills the requirements and that appears feasible to build is presented.