Observation of plasma density dependence of electromagnetic soliton excitation by an intense laser pulse

Abstract

Borghesi, M. (2011). Observation of plasma density dependence of electromagnetic soliton excitation by an intense laser pulse.

Observation of a strong correlation between electromagnetic soliton formation and relativistic self-focusing for ultra-short laser pulses propagating through an under-dense plasma

“…33 We note that previous studies on the EM soliton have largely concentrated on the underdense plasma close to the critical surface and have indicated that solitons are not observed if the plasma density is far below n c . 10,20,30 However, the plasma density employed in our experiments was relatively low. We know soliton generation is closely connected with the initial plasma density n e0 , because a key condition for EM field trapping is that the frequency in the rear portion of an intense laser pulse decreases to the local plasma frequency.…”

“…This is mainly because Raman scattering is neglected in deriving the formula, which attributes the frequency downshift to the energy depletion. 7,9,30 Raman scattering though is fundamental in decreasing the laser frequency and thus soliton formation. 24 In the low-density region, the cascade-to-condensate caused by SRS tends to weaken.…”

“…This can be explained from an analytical formula giving the interaction length for soliton generation as l depl % l pulse ðx=x pe Þ 2 . 7,9,18,30 According to the formula, the interaction length is proportional to the pulse length but inversely proportional to the plasma density. At a comparable initial density, a 1 ps pulse will create a soliton at a distance much further than a 30 fs pulse.…”

Three dimensional electromagnetic wavepackets in a plasma: Spatiotemporal modulational instability

“…Many particle in cell (PIC) simulations [41][42][43][44][45][46][47] and experimental investigations [48][49][50][51] reveal the appearance of multidimensional EM localized structures and light bullets in laser plasmas. It is believed that 44,45 nearly 25%-40% of the laser pulse energy goes into the generation of these well localized concentrations of electromagnetic energy, which can play an important role in the laser plasma interaction process.…”

Self-Thomson Backscattering of Ultra-Intense Laser from Thin Foil Target

“…Thus, the numerical identifications of solitons, among the different kinds of coherent structures that are formed by an intense laser pulse in a plasma, stimulated a renewed interest in developing an analytical model and in envisaging ways of detecting solitons experimentally [4]. The em soliton [5] found in 1D and 2D simulations consist of slowly or nonpropagating electron density cavities inside which an em field is trapped and oscillates coherently with a frequency below the unperturbed plasma frequency and with a spatial structure corresponding to half a cycle.…”