The generation of intense Planck radiation by laser

Pulsed laser and particle beams offer prospects of generating intense Planck radiation in mm-size cavities of high- Z material. In order to achieve isotropy and high temperature, confinement of the radiation through multiple reemission by the wall of the cavity is necessary. This requires heating of the wall material to a certain depth, necessitating energetic pulses from the source. In experiments performed at the Max-Planck-Institut für Quantenoptik (MPQ) at Garching and at the Institute of Laser Engineering (ILE) at Osaka with laser light of 1.3, 0.53 and 0.44 μm wavelength, brightness temperatures up to 2.2 × 10 6 K have been achieved in gold cavities with one- to two- fold reemission of the x-rays. A more favourable laser-plasma interaction and x-ray conversion efficiency may be obtained by shorter wavelength lasers.