Abstract
In laser-solid interactions, electrons may be generated and subsequently accelerated to energies of the order-of-magnitude of the ponderomotive limit, with the underlying process dominated by direct laser acceleration. Breaking this limit, realized here by a radially-polarized laser pulse incident upon a wire target, can be associated with several novel effects. Three-dimensional Particle-In-Cell simulations show a relativistic intense laser pulse can extract electrons from the wire and inject them into the accelerating field. Anti-dephasing, resulting from collective plasma effects, are shown here to enhance the accelerated electron energy by two orders of magnitude compared to the ponderomotive limit. It is demonstrated that ultra-short radially polarized pulses produce super-ponderomotive electrons more efficiently than pulses of the linear and circular polarization varieties.
Highlights
The generation of energetic electrons by laser interaction with matter has witnessed considerable development over the past four decades
The accelerating phase is hard to define in linearly polarized (LP) and circularly polarized (CP) pulses, electrons are gathered at azimuthally dependent phases
The antidephasing acceleration (ADA) regime works with LP and CP pulses, resulting in the electrons getting accelerated by a continuous stable phase
Summary
The generation of energetic electrons by laser interaction with matter has witnessed considerable development over the past four decades. An experiment in which a microwire, used as an advanced solid target to generate and transport hot electrons over millimeters [23,24,25], has recently demonstrated reaching several times the ponderomotive energy, when LP laser pulses are used [26,27]. Our main result ADA is put forward as an extremely efficient mechanism for electron acceleration directly from a solid target. Half-cycle extreme-ultraviolet pulse generation [34], bremsstrahlung x-ray generation [35], and the generation of terahertz radiation [36] Progress in these applications stands to be advanced by the availability of more energetic, shorter, and denser electron bunches. Self-injection with a small dephasing rate is caused by the collective motion of the plasma electrons and the complex laser-field variations
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