High-intensity synchrotron radiation from compact magnetic-plasma structures

Abstract

As technological devices become more compact, their ability to generate small-scale electric and magnetic structures becomes increasingly important. In most cases, reducing the size of these structures runs into stringent technical limits, especially in terms of the field amplitudes and the shortest length scales attainable. Plasma is an attractive medium in this context because of its ability to sustain strong fields on small spatial scales. Successful examples include high-gradient electrostatic structures—generated by the propagation of an intense laser pulse in a plasma—that are used to accelerate particles to high energies in compact systems.1 Excitation of analogous periodic-magnetostatic structures to drive a plasma magnetic mode (PMM) by colliding a light pulse with a relativistic ionization front had been predicted theoretically,2, 3 but a method to detect and characterize PMMs was designed only recently.4 Propagation of a relativistic electron beam through the PMM can provide ultrashort-wavelength synchrotron radiation,5 in a similar fashion to beam propagation in the undulator structure of a free-electron laser.6 In addition, narrow spectra and, consequently, high-intensity radiation can be generated, since the larger the number of oscillation periods in the structure, the narrower the spectrum of the resulting emission. Development of a compact radiation source would offer a powerful tool to study the dynamics of materials on the timescale of atomic motions7 and for biomolecular imaging.8 We show that controlled excitation of the magnetic structure is possible with existing state-of-the-art laser technology, thus enabling its exploration, in particular, for the generation of high-intensity synchrotron radiation. Figure 1. Schematic setup used to generate synchrotron radiation through the propagation of an electron beam in the plasma-magneticmode (PMM) structure.