Collimation

Non-linear optics is employed with sextupole magnets for 1.2km/0.75TeV(beam energy) collimator in order to selectively blow up the tail part of the beam. The collimated beam profile is $6 \sigma_x \times 40 \sigma_y$.For NLC, linear optics is employed for 2.4km/0.5TeV(beam energy) collimator. The collimated beam profile is $7 \sigma_x \times 35 \sigma_y$.Shorter collimation section is desired generally. New idea is welcome, and we may expect exotic ideas such as laser, liquid metal-collimation(?).