Hollow Bessel beams formation for optic breakdown of gases

Bessel (B) beams represent the new propagation manner of EM radiation with field radial distribution described Bessel function which persists along all the region of the beam existence and propagation. The beam feature of the most interest seems to be its ability to generate long and narrow plasma channels in media, which, already today, promises important applications in X-ray laser problem, for pump energy transformation being of high efficiency. All previous explorations dealt with zero under B-beams. A new device for formation of high order of hollow B-beams (HB-beams) was elaborated. In the device an axicon formatting zero order B-beam was added by special optic element open-quotes phase screwclose quotes. The element has linear dependence of optic path from an azimuth angle var-phi and the constant path at different radii r. The optic path increment on the whole revolution has to be of mλ, where m is an order of B-beam configuration, and λ-the incident radiation wavelength. HB-beams peculiarities cause fundamental and applied interest to gas breakdown by them. In particular, it seems that matter will be compressed inside the tube towards its axis and pushed out from outside layer. Generated dense plasma channel surrounded by rare shell may be utilized both in X-ray laser and in other problems such as inertial plasma confinement