Near field accelerators

The Workshop has made enormous gains in our understanding. Many scaling laws of linac behavior with wavelength have been defined, some probably for the first time. A comparison has been made between a conventional and grating linac, also probably for the first time. A problem in transverse stability of the grating accelerator was exposed but also solved at the workshop with a great net gain in understanding. Loading of linacs appears not to be independent on wavelength, it had not previously been studied for a laser accelerator. The limits on accelerating field as a function of wavelength have been studied. A gain of a factor of 10 is likely if the wavelength can be reduced to the 1 cm range. After that the gains are small unless it is acceptable to destroy the structure. If this is allowed, as could be the case for a grating consisting of liquid ripples, then plasma development will limit the fields. A first calculation suggests that very high gradients may be attainable. The most remarkable feature of laser driven grating accelerators are the low rf energies required to attain high beam energies for a few particles. One example is of a 1 TeV acceleratormore » driven by a 60 Joule laser.« less