Abstract
The idea of using a crystal lattice or a superlattice as an undulator for a free electron laser is explored. A purely classical treatment of relativistic positrons channeling through the proposed structure is performed in a self-consistent fashion involving the wave equation for the radiating electromagnetic field and the kinetic equation for the positron distribution function. The (positive) gain coefficient for a forward radiating field is obtained in closed form. Matching the Kumakhov channeling resonance to the undulator frequency further enhances the gain. This result, combined with a feedback mechanism arising from Bragg diffraction within the basic crystal lattice, leads to an instability of the radiation inside the crystal. A simple threshold condition involving the atomic scattering factor and the net gain is formulated. Finally, a numerical estimate of the Kumakhov-enhanced gain coefficient is made for the (110) planar channeling in a strain-modulated Si superlattice.
Original language | English (US) |
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Pages (from-to) | 177-188 |
Number of pages | 12 |
Journal | Journal of Applied Physics |
Volume | 60 |
Issue number | 1 |
DOIs | |
State | Published - 1986 |
ASJC Scopus subject areas
- General Physics and Astronomy