Device on basis of a bent crystal with variable curvature for particle   beams steering in accelerators
  Recently it was proposed to apply a bent single crystal with decreasing curvature instead of uniform bending for improvement of extraction and collimation of a circulating beam in particle accelerators. In the given paper created crystal devices with a variable curvature, realizing this idea are described. Results of measurement of curvature along a crystal plate are informed. It is shown, that with the help of the developed devices it is possible to carry out also high energy beam focusing. The mathematical description of this process is proposed. 
A. G. Afonin, V. T. Baranov, M. K. Bulgakov, Yu. A. Chesnokov, P. N.   Chirkov, E. V. Lobanova, I. S. Lobanov, A. N. Lunkov,...
physics.acc-ph