Rare gas or metal clusters are known to absorb laser energy very efficiently. Upon cluster expansion the Mie plasma frequency may become equal frequency. This linear resonance has been well studied both experimentally and theoretically employing pump probe schemes. In this work we focus on few-cycle regime early stage of dynamics where is not met but nevertheless efficient absorption persists. By retrieving time-dependent oscillator frequencies from particle-in-cell simulation results, show...

The harmonic emission from cluster nanoplasmas subject to short, intense infrared laser pulses is analyzed by means of particle-in-cell simulations. A pronounced resonant enhancement the low-order yields found when Mie plasma frequency ionizing and expanding resonates with respective frequency. We show that a strong, nonlinear coupling electrons field inhibits coherent electron motion, suppressing emitted radiation restricting spectrum only harmonics. pump-probe scheme suggested monitor...

Harmonic emission from cluster nanoplasmas subject to short intense infrared laser pulses is studied. In a previous publication [M. Kundu et al., Phys. Rev. A 76, 033201 (2007)] we reported particle-in-cell simulation results showing resonant enhancements of low-order harmonics when the Mie plasma frequency ionizing and expanding resonates with respective harmonic frequency. Simultaneously found that high-order were barely present in spectrum, even at high intensities. The current paper...

Intense laser produced plasmas generate hot electrons which in turn leads to ion acceleration. Ability faster ions or hotter using the same parameters is one of main outstanding paradigms intense laser-plasma physics. Here, we present a simple, albeit, unconventional target that succeeds generating 700 keV carbon where conventional targets for at most 40 keV. A few layers micron sized bacteria coating on polished surface increases energy coupling and generates plasma more effective...

In a previous paper [Phys. Rev. Lett. 96, 123401 (2006)] we have shown by means of three-dimensional particle-in-cell simulations and simple rigid-sphere model that nonlinear resonance absorption is the dominant collisionless mechanism in intense, short-pulse laser cluster interaction. this present more detailed account matter. particular show efficiency almost independent polarization. model, absorbed energy increases many orders magnitude at certain threshold intensity. The results display...

It is known that rare-gas or metal clusters absorb incident laser energy very efficiently. However, due to the intricate dependencies on all and cluster parameters, it difficult predict under which circumstances ionization absorption are optimal. With help of three-dimensional particle-in-cell simulations xenon (up 17256 atoms), shown for a given pulse cluster, an optimum wavelength exists corresponds approximate transient, linear Mie-resonance ionizing at early stage negligible expansion....

We demonstrate that the interaction of intense femtosecond light on a plain solid substrate can be substantially altered by few micron layer coating bacterial cells, live or dead. Using E. Coli we show at an intensity 10(16)W cm(-2), bremsstraahlung hard x-ray emission (up to 300 keV), is increased more than two orders magnitude as compared glass slab. Particle-in-cell simulations carried out modeling cells ellipsoidal particles hot electron generation indeed enhanced presence...

The interaction of intense laser light with atomic nanoclusters is studied a rigid sphere model and three-dimensional particle-in-cell simulations for ultrashort pulses pulse durations $\ensuremath{\tau}$ down to one optical period $T$ below. In this subcycle regime not all conventional models are applicable may lead unphysical absorption energy. For allowed models, we show that given peak intensity, cluster, the efficiency increases as shortens reaches maximum value in regime. deuterium...

In this work, we re-examine collisional absorption of 800 nm wavelength laser pulses in under-dense plasma. For a given temperature and density the plasma, most conventional models electron-ion collision frequency νei, with Coulomb logarithm independent electron-ponderomotive velocity, show that νei corresponding fractional α remain almost constant (or decrease slowly) up to value Ic peak intensity I0 pulse, then as ≈I0−3/2 when is increased beyond Ic. On contrary, below some (≲10 eV)...

Recent studies [e.g., Sci. Rep. 12, 11256 (2022)] on laser interaction (for a wavelength of 800 nm and intensity greater than ${10}^{16}\phantom{\rule{4pt}{0ex}}\mathrm{W}/{\mathrm{cm}}^{2}$) with deuterium nanocluster in an ambient magnetic field ${B}_{0}$ demonstrate that collisionless absorption light occurs two stages via anharmonic resonance electron-cyclotron (ECR) or relativistic ECR (RECR) processes. The auxiliary enhances the coupling to cluster electrons improved frequency matching...

Linear resonance (LR) absorption of an intense 800~nm laser light in a nano-cluster requires long pulse > 100~fs when Mie-plasma frequency ($\omegaMie$) electrons the expanding cluster matches frequency~($\omega$). For short duration condition for LR is not satisfied. In this case, it was shown by model and particle-in-cell (PIC) simulations [Phys. Rev. Lett. 96, 123401 (2006)] that absorb energy anharmonic (AHR) position-dependent $\Omega[r(t)]$ electron self-consistent potential satisfies...

Recently, it has been greatly appreciated that intense light matter interaction is modified due to the nano- and microstructures in target by--surface plasmons, laser energy localization scattering etc. Extreme intensities produce dense plasmas collective mechanisms generate energetic electrons, ions hard x-rays. postulated anharmonic electron motion, driven by ultrashort, high-intensity pulses, provides a universal mechanism for absorption. Here, we provide first demonstration of...

We examine asymmetric expansion of argon clusters illuminated by 800 nm laser pulses duration ≈23fs, using three-dimensional particle-in-cell (PIC) simulation. For this short pulse duration, energy absorption cluster electrons is dominated the nonlinear resonance (NLR) process [Phys. Rev. Lett. 96, 123401 (2006)]. In work, we concentrate, particularly, on ionic outcome in NLR regime and show that higher charge states ions are produced along polarization than transverse directions leading to...

Identification of the basic processes responsible for an efficient heating intense laser produced plasmas is one important features high intensity matter interaction studies. Collisionless absorption due to anharmonicity in self-consistent electrostatic potential plasma, known as anharmonic resonance (AHR), has been proposed be a mechanism but clear experimental demonstration needed. Here, we show that microstructured targets enhance X-ray emission and polarization dependence ascribes...

We demonstrate a simple method of preparing structured target for enhanced laser-driven proton acceleration under target-normal-sheath-acceleration scheme. A few layers genetically modified, clinically grown micron sized E. Coli bacteria cell coated on thin metal foil has resulted in an increase the maximum energy by about 1.5 times and total yield is approximately 25 compared to unstructured reference at laser intensity 1019 W/cm2. Particle-in-cell simulations system shows that structures...

Pronounced maximum absorption of laser light irradiating a rare-gas or metal cluster is widely expected during the linear resonance (LR) when Mie-plasma wavelength ${\ensuremath{\lambda}}_{\mathrm{M}}$ electrons equals $\ensuremath{\lambda}$. On contrary, by performing molecular dynamics (MD) simulations an argon irradiated short 5-fs (FWHM) pulses it revealed that, for given pulse energy and cluster, at each peak intensity there exists $\ensuremath{\lambda}$---shifted from...

A nanocluster ionized by a femtosecond pulse of wavelength larger than the cluster size is known to set up an electron cloud that oscillates with respect ion cloud. Most theoretical frameworks on understanding ionization are built this dipole oscillation model. Here, we probe pump-probe absorption spectroscopy. linearly polarized pump sets and polarization comes after prescribed time varied, differential changes in measured. The dependence gives direct measure asymmetry ellipticity...

In a previous paper [M. Kundu, Phys. Plasmas 21, 013302 (2014)], fractional collisional absorption (α) of laser light in underdense plasma was studied by using classical scattering model electron-ion collision frequency ν(ei), where total velocity v=√[v(th)(2)+v(0)(2)] (with v(th) and v(0) as the thermal ponderomotive an electron) dependent Coulomb logarithm lnΛ(v) shown to be responsible for anomalous (unconventional) increase ν(ei) α(∝ν(ei)) with intensity I(0) up maximum value about I(c)...

Absorption of laser light in plasma via electron-ion collision (inverse bremsstrahlung) is known to decrease with the intensity as I0-3/2 or electron temperature Te-3/2 where Coulomb logarithm ln Λ = 0.5ln(1 + k2min/k2max) expression frequency vei assumed be independent ponderomotive velocity v0 E0/ω which unjustified. Here k-1min vth/max(ω, ωp), and k-1max Z/v2th are maximum minimum cut-off distances colliding from ion, vth √Te its thermal velocity, ω, ωp frequency. Earlier a total v (v20...