Degree Granting Department
Alex Volinsky, Ph.D.
Nathan Crane, Ph.D.
Delcie Durham, Ph.D.
Thin Films, Thermal Mismatch, Slope Error, Free Electron Laser, Uneven Heating
A novel, no-contact approach to X-ray mirror bending control is presented here,
proposed for use on the beamlines of the European X-ray Free Electron Laser (XFEL)
project. A set of mirrors with tunable bending radii are desired, that will maintain their
optical properties even as the beam incidence causes local heating. Various mechanical
bending mechanisms have been proposed and used on other beamlines, which can take up
a lot of physical space, demanding more vacuum power, while using expensive high
precision servomotors. Rather than bend the mirror by mechanical means, it is proposed
to heat the mirror to produce the desired bending. This could work two ways. One
scenario calls for a finely tunable heat lamp to irradiate the back surface of the mirror
while the X-ray laser heats the front side. With appropriate tuning, simulations show that
this approach can keep the mirror flat, and perhaps produce a circular profile. The
second scenario is similar to the first, but a thin film of tungsten is added to the back of
the silicon mirror. This scenario calls for the temperature of the mirror to change
homogenously to affect the desired bending, and in this case the profile should be
cylindrical. In both scenarios the uneven nature of the incident radiation causes
distortions that may be undesirable. Both scenarios are simulated and it is shown that the
stress produced by a metal film may minimize this distortion. The response time of the
mirror and configuration of both the heating and cooling mechanism are also considered.
Scholar Commons Citation
Weinbaum, Michael, "A Novel Approach to X-ray Mirror Bending Stability and Control" (2010). Graduate Theses and Dissertations.