Comment on Lasetron

In a recent paper [1] Kaplan and Shkolnikov propose to generate intense ultra-short pulses of electromagnetic radiation in the range ∼ 10−21 s (zeptosecond) and large magnetic fields by using a petawatt electron laser irradiating a small solid particle or a piece of wire of a submicron size. In this comment we would like to point out that the method proposed in Ref. [1] will not achieve the desired results. Submitted to Physical Review Letters. Work supported in part by the Department of Energy contract DE-AC03-76SF00515. 2In a recent paper [1] Kaplan and Shkolnikov propose to generate intense ultrashort pulses of electromagnetic radiation in the range ∼ 10−21 s (zeptosecond) and large magnetic fields by using a petawatt electron laser irradiating a small solid particle or a piece of wire of a submicron size. In this comment we would like to point out that the method proposed in Ref. [1] will not achieve the desired results. It is assumed in Ref. [1] that under the influence of the circularly polarized laser fiel