Additional focusing of a high-intensity laser beam in a plasma with a density ramp and a magnetic field

Abstract

Propagation of a high power Gaussian laser beam through a plasma with a density ramp where a magnetic field is present has been investigated. The spot size of the laser beam decreases as the beam penetrates into the plasma due to the role of a plasma density ramp. The studies show that the combined effect of a plasma density ramp and a magnetic field enhances the self-focusing property of the laser beam. Both factors not only reduce the spot size of the laser beam but also maintain it with only a mild ripple over several Rayleight lengths.

Self-focusing and defocusing of TEM0p Hermite–Gaussian laser beams in collisionless plasma

“…Correspondingly there are thus four values of P cr viz; P crx1 , P cry1 , P crx2 and P crx2 which are obtained by substituting the A 2 0p for respective modes in Eq. (16). Thus, with knowledge of the R d and E 2 0cr values, Eqs.…”

“…(16) and (17) we determine the values of E 2 0cr and find that there are two values of E 2 0cr for each of the x and y directions. Correspondingly there are thus four values of P cr viz; P crx1 , P cry1 , P crx2 and P crx2 which are obtained by substituting the A 2 0p for respective modes in Eq.…”

“…Gupta et al [15] have observed a plasma density ramp of a suitable length can reduce these oscillations. Furthermore, they have also predicted a magnetic field acts as a catalyst for self-focusing of a laser beam during propagation in a plasma density ramp [16].…”

The effect of external magnetic field on the density distributions and electromagnetic fields in the interaction of high-intensity short laser pulse with collisionless underdense plasma

“…Although some valuable experimental works have been reported, the introduced analytical works did not properly explain the fundamental parameters of the magnetized collisionless plasma, including electric field oscillation, electron density distribution or the derived equations, being related to very special conditions [22,23]. In the recent studying of plasma, such as ponderomotive acceleration of plasma in the applied magnetic field and improving of self-focusing in presence of the applied external magnetic fields, the range of magnetic field intensities are in the range of tens of megagauss [24,25]. Based on the report of Gupta et al [25], they did not have the effect of external magnetic field up to 20 MG in an underdense subrelativistic plasma and the effect is enhanced by increasing the magnetic field intensity up to 45 MG, where we have noticed an almost similar dependence of mentioned parameters to the magnetic field intensity in the present analytical work.…”

“…In the recent studying of plasma, such as ponderomotive acceleration of plasma in the applied magnetic field and improving of self-focusing in presence of the applied external magnetic fields, the range of magnetic field intensities are in the range of tens of megagauss [24,25]. Based on the report of Gupta et al [25], they did not have the effect of external magnetic field up to 20 MG in an underdense subrelativistic plasma and the effect is enhanced by increasing the magnetic field intensity up to 45 MG, where we have noticed an almost similar dependence of mentioned parameters to the magnetic field intensity in the present analytical work. Although some valuable experimental works are reported, the introduced analytical works did not properly explain the fundamental parameters of the magnetized plasma including electric and magnetic field oscillations or the derived equations being related to very special conditions [26][27][28][29][30][31][32].…”