Light Source Physics

I'm continuing on this work of connecting electron beam dynamics to x-ray dynamics.

We compute the equilibrium second moment matrix which describes a Gaussian electron beam.  There are multiple codes for this, e.g. Elegant or AT.

Next, this is input for a code that computes the radiation.  The magnetic field must be described as input here.  One code for this is Radia.  For the radiation source computation: there are modules in XOP for this.  SRW is a powerful code for computing wavefronts.  One can compute the Stokes parameters which give polarization as well.  A question: is the coherence described by the wavefront in SRW?  We know that the Wigner function, or Brightness function, or mutual intensity correlation function can be used for this.  But this isn't computed in SRW.  Next, how to sample rays to feed into Shadow or mcXtrace?

My other project is to work on collective effects in electron beams.  We would like to be able to predict the instability thresholds.  We would also like to know how various parameters change due to the collective effects.  For example, energy spread changes due to the microwave instability. There can be emittance growth from impedance as well.

Areas of beam dynamics with unsolved problems:

Collective effects-

Distribution with diffusion, damping, feedback.  Instability due to one effect may be limited by other effects.  Is there a theory in this range ?

Want to know emittance growth, non-Gaussain distributions.

Analysis of Fokker-Planck.  Maybe more terms as in Master equation is needed sometimes?

Single particle dynamics :

Given a one turn map- find the long behavior.  What is the stable region ?  What happens when damping is added ?  Can we find the right parameters from the one-turn map that effect the long term behavior ?

Has this problem been solved in chaotic map literature?

Radiation from electron beam-

Interface between electron beam and photons.  Definition of Wigner function.  Sometimes negative.  Not fully understood.

Need to define photon beam operationally based on how the photons will interact, be focussed by optics, etc.