Аннотация:Brunel harmonics appear in the optical response of an atom in process of laser-induced
ionization, when the electron leaves the atom and is accelerated in the strong optical field
[1-3]. In contrast to recollision-based harmonics, the Brunel mechanism does not require the electron returning to the core.
Here we show that in the presence of a strong terahertz (THz) eld, which is just below the
boundary of an eective tunnel ionization, even a weak driving eld at the optical frequencies
allow for generating Brunel harmonics especially effectively. Importantly, the strong ionizing THz pump also suppresses recollisions, making the Brunel mechanism dominant in a wide
spectral range. High-order Brunel harmonics may form a coherent carrier-envelope-phase
insensitive supercontinuum, compressible into an isolated pulse with the duration down to
100 attoseconds.