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This study has been conducted to examine the combined impact of a wiggler magnetic field and an exponential plasma density ramp on a q-Gaussian laser beam (q-GLB) in underdense plasma. Our observations revealed that the implementation of the wiggler magnetic field in the presence of exponential plasma density ramp led to a reduction in the beam width parameter of q-GLB and enhances self-focusing by pushing plasma electrons away from the beam axis. The wiggler magnetic field also combats the defocusing tendency of plasma density ramp, hence enabling q-GLB to attain a minimal spot size and retain it up to several Rayleigh lengths. It has been revealed that the self-focusing in magnetized plasma is affected by the qparameter, with higher values leading to stronger self-focusing. The implications of these findings have potential to revolutionize a diverse range of laser-based applications including advanced particle accelerators, ICF, and sustainable energy systems.

A novel scheme for electric field-induced strong terahertz (THz) emission by beating two filamented spatial-Gaussian laser beams (with intensities 1014Wcm-2)in the pre-existing underdense magnetized plasma is proposed. The coupling between the nonlinear density and nonlinear velocity of the plasma electrons results in the strong nonlinear current which drives the efficient THz radiation in the presence of the D.C. electric and magnetic fields. The contribution of the electron temperature on the THz generation has been investigated. The modulation index also makes a significant contribution to the enhancement of the nonlinear current density and normalized THz amplitude. With the help of a magnetic field, D. C. electric field, D.C. drift speed, and modulation index, one can easily tune the THz radiations for medical and astronomical applications. The normalized amplitude of emitted THz radiation is observed to vary with the externally applied electric field, magnetic field, normalized frequency, drift velocity of electrons, thermal velocity of electrons, temperature of plasma electrons, and modulation index of incident laser beams. The frequency of the emitted THz radiation (corresponding to 25.0kG) is found to lie in the frequency range of molecular rotational and vibrational spectra of deoxyribonucleic acid. As a result, emitted THz radiation in the present scheme can play an important role in developing a new technique to distinguish between healthier and non-healthier tissues of human beings. The emitted THz radiation shows sensitive behavior toward water particles. Due to this, emitted THz radiation can also be used to detect water at the surface of the earth as well as on other celestial bodies.

Objective: To evaluate the environmental and economic impact of teleophthalmological services provided by a primary (rural) and tertiary (urban) eyecare network in India. Methods: This prospective study utilised a random sampling method, and administered an environmental and economic impact assessment questionnaire. The study included 324 (primary: 173; tertiary: 151) patients who received teleconsultations from July to September 2022. The primary network (rural) used a colour-coded triage system (Green: eye conditions managed by teleconsult alone; yellow: semi-urgent referral within 1 week to a month, red: urgent referral within a day to a week). The tertiary network (urban) included new and follow-up patients. The environmental impact was assessed by estimating the potential CO2emissions saved by avoiding travel for various transport modes. Economic impact measured by the potential cost savings from direct (travel) and indirect (food and wages lost) expenses spent by yellow and red referrals (primary) and the first-visit expenses of follow-up (tertiary) patients. Results: The primary rural network saved 2.89 kg CO2/person and 80 km/person. The tertiary urban network saved 176.6 kg CO2/person and 1666 km/person. The potential cost savings on travel expenses were INR 19,970 (USD 250) for the primary (average: INR 370 (USD 4.6) per patient) and INR 758,870 (USD 9486) for the tertiary network (average: INR 8339 (USD 104) per patient). Indirect cost savings (food and wages) were of INR 29,100 (USD 364) for the primary and INR 347,800 (USD 4347) for the tertiary network. Conclusion: Teleophthalmology offers substantial environmental and economic benefits in rural and urban eyecare systems.

Laser wakefield acceleration is a frequently utilised research methodology for enhancing the energy levels of lighter charged particles, specifically electrons, to relativistic magnitudes. In this investigation, we utilised a linear polarised Gaussian-like laser pulse that propagated along the z-axis through cold collisionless underdense plasma in weakly nonlinear regime. An external planer magnetic wiggler field is applied along the y-axis. The influence of various critical parameters, such as amplitude and propagation constant of wiggler magnetic field, amplitude of laser electric field and laser pulse length on the wakefield and electron energy gain has been studied. A wiggler-assisted laser wakefield accelerator, the electron energy and wakefield evolution can be tuned by the wiggler magnetic field strength. The numerical findings demonstrate that by varying the strength of wiggler magnetic field and laser electric field, the amplitude of the wakefield is affected significantly. Furthermore, the equality of the order of pulse length and plasma wavelength is essential to obtain energy efficient acceleration mechanism. By employing specific parameters, a maximum energy increase of 2.26 GeV is achieved. This research will aid in the development of an energy-efficient electron acceleration technology by choosing suitable laser and plasma parameters.

Graphical Abstract:

In advanced accelerator physics, Direct Laser Acceleration is a technique employed to directly accelerate charged particles, like electrons, by harnessing the electric field of a laser. In this investigation, we have considered a low intensity q-Gaussian laser pulse interacting with electrons in vacuum. Coupled differential equations for electron velocity and relativistic factor is obtained which are solved using numerical simulations. Electron energy gain and relativistic factor are examined by varying various laser parameters like q-parameter, laser electric field amplitude and beam waist. Our research outcomes show that with the selected specific parameters, electron energy gain show positive correlation with all these parameters. An electron with initial energy of 0.05 MeV is interacted with the laser pulse, and a maximum of 660.93 MeV electron is obtained with a laser pulse of intensity 7.64 × 1022W/m2. This study is useful for researchers to obtain electrons suitable for scientific research-like plasma wakefield accelerators, medical diagnosis and material physics. Extensive research and technological advancements are required to address the existing obstacles and fully unlock the capabilities of electron acceleration.

In this novel scheme, we have theoretically analysed the impact of characteristic parameters on THz radiation generation by propagating two collinear laser beams of slightly different frequencies (ω1,ω2) in the array of quasi metallic carbon nanotubes (QMCNTs) based plasma. The laser beams interact with quasi-metallic carbon nanotubes and ionise the atoms of quasi-metallic nanotubes. Electrons of QMCNTs absorb the photon energy of laser beams and experience nonlinear ponderomotive force, thus producing a nonlinear current at the beat frequency. The nonlinear current density of plasma electrons of QMCNTs acts as a source for terahertz generation at the beat frequency. Normalised terahertz power multiplies extensively with the increased length and width of nanotubes. As the electron density of plasma of quasi-metallic nanotubes approaches plasma resonance i.e., atωP∼2.2ω,oscillatory electrons of nanotubes-based plasma produce resonantly enhanced terahertz power. Change in length and width of QMCNTs significantly broadens the resonance peaks of terahertz power. For typical values of parameters, the resulting energy conversion efficiency is ∼10-4and this can be used for imaging and security scanning for non-destructive testing.

Laser-driven plasma accelerators have attracted attention for their ability to achieve ultra-high gradient acceleration and produce high-quality particle beams. Vacuum-based laser acceleration offers advantages over plasma mediums by eliminating instabilities associated with plasma interactions. This study investigates electron acceleration dynamics using two tightly focused, linearly polarized laser beams with controlled frequency chirp in vacuum. The research aims to optimize parameters for electron energy gain, emphasizing the significance of periodic frequency chirp in enhancing acceleration efficiency. Mathematical analyses elucidate the interaction mechanisms between electrons and tightly focused laser beat waves. Results demonstrate substantial energy gains in the MeV range, with insights into the influence of laser intensity, chirp parameter, and initial phase angle on electron acceleration. The study highlights the importance of precise parameter optimization for maximizing electron energy gain in vacuum-based beat wave acceleration, contributing valuable insights to particle physics and materials science advancements.

Using a q-Gaussian laser beam, this research investigates the phenomenon of third harmonic generation (THG) within the magnetized plasma. We identify the conditions regulating effective THG by fusing non-extensive statistical mechanics with plasma physics. Our findings highlight the crucial roles that plasma density and magnetic field strength impart. The effects of the wiggler magnetic field, laser intensity, and plasma frequency on the THG efficiency are studied numerically. It is found that the wiggler magnetic field can significantly enhance the THG efficiency by providing additional momentum to the third harmonic photons. Due to density perturbation electrons quiver velocity overlaps and a photon of double frequency is generated so the Wiggler magnetic field by imparting a Lorentz force provides additional momentum to the photons of the third harmonics hence the efficiency is enhanced. The THG efficiency is also found to increase with laser intensity and plasma frequency. These discoveries show promise for a variety of applications, including real-time plasma diagnostics and the creation of portable, high-frequency sources for wireless communication and medical imaging. This research advances both theoretical understanding and technological innovation by clarifying the complex interplay of magnetized plasmas, q-Gaussian lasers, and nonlinear optics.

This study presents a novel method to improve the efficiency of THz generation by optimising laser and plasma parameters and using Sinh-Gaussian beams in a magnetised plasma environment. Intense laser pulses, when combined with a pre-ionized plasma, produce powerful electromagnetic fields that can efficiently emit THz radiation. We conduct a thorough analytical study of the effects of important factors, such as plasma density, decentered parameter of Sinh function, transverse distance, and external magnetic field strength, on the efficiency of THz generation using theoretical studies. THz efficiency has positive corelation with plasma density and decentered parameter while external magnetic field has no significant effect on generated THz efficiency. The results of our study show substantial improvements in the power and spectrum properties of THz output by implementing the suggested optimisation methods. This research provides useful insights that can be used to improve THz generating techniques. These techniques have a wide range of applications, including spectroscopy, imaging, communications, and sensing.

The utilization of Terahertz (THz) radiation has garnered considerable interest in recent times owing to its wide-ranging applications in varied domains such as communication, imaging, and spectroscopy. This work specifically examines the production of THz radiation by utilizing Sinh-Gaussian laser pulses. The Sinh-Gaussian pulse has a distinct profile that has shown potential attributes for energy effective THz synthesis. In the present study, two Sinh-Gaussian pulses are considered to propagate through a uniform underdense homogenous collisional plasma. Nonlinearity produced by two pulses generates a nonlinear current density which further generates the THz waves. The effect of decentred parameter and collisional frequency on THz efficiency are analytically investigated in this study. Our study reveals that with the increase in decentred parameter or decrease in collisional frequency, energy efficiency of generated THz can be enhanced. The distinctive attributes of this pulse shape present new opportunities for optimizing THz sources, hence facilitating progress in ultrafast optics and terahertz technology.

In contrast to conventional particle accelerators, laser wakefield acceleration (LWFA) has become a practical method for producing ultra-relativistic electron beams within substantially smaller spatial extents. This work aims to conduct a comparative investigation of electron acceleration by employing two different laser pulse patterns, namely Gaussian and cosh-Gaussian. The utilization of these pulse profiles is prevalent in the context of laser-plasma interactions, which give rise to diverse dynamics in electron acceleration. An analytical examination of the electron acceleration processes induced by cosh-Gaussian and Gaussian laser pulses in a uniform plasma has been exhaustive. This research examines the correlation between wake potential, wakefield, and electron energy gain for both pulse patterns, in consideration of several parameters including laser intensity, pulse length, and parameter w0. The results of our analyses indicate that the generation of cosh-Gaussian pulses is a more suitable method for generating wake potential, wakefield, and electron energy gain. By optimizing the beam parameter w0and the length, a cosh-Gaussian pulse profile can increase the energy by as much as 5.1 GeV. The findings of our research provide substantial knowledge regarding the comparative efficacy of cosh-Gaussian and Gaussian pulse-driven LWFA methods. This contributes to the broader comprehension of interactions between lasers and plasmas, particularly in the context of particle acceleration methods for future advancements.

The presence of an external magnetic field exerts a substantial influence on the phenomenon commonly referred to as nonlinear laser plasma interaction. External magnetic field exerts a notable influence on the efficiency of THz creation, harmonic generation, self-focusing, and electron acceleration by laser wakefield acceleration (LWFA). An analytical study is conducted to examine the impact of an external magnetic field on the acceleration of the laser wakefield. This investigation utilized a sin-Gaussian pulse profile. To achieve this objective, a fundamental second-order differential equation is generated for the wake potential. Furthermore, equations describing the wakefield generated and the resulting increase in electron energy are derived. The sin-Gaussian pulse is used in the appropriate equations to derive an analytical solution for the laser wakefield, the electron energy gain, and the laser wake potential. Curves have been constructed using experimentally tractable parameters to show the variation in LWFA. The findings of this study indicate a positive correlation between the presence of an external magnetic field and the laser wake potential, laser wakefield, and electron energy gain. Moreover, the optimization of parameters related to the sine function and the Gaussian function is achieved. Improved electron acceleration can be achieved when the value of Lis equal to 0.2λP(λPis plasma wavelength) and the value of r0exceeds 0.5λP. Our findings will enable the researchers to employ an external magnetic field and improve the laser characteristics to obtain energy efficient electron acceleration.

The production of terahertz (THz) radiation via the interaction between lasers and plasmas is an intriguing and swiftly progressing domain of study within the realms of optics and plasma physics. The aforementioned procedure entails the utilisation of high-intensity laser pulses to engage with a plasma, hence leading to the generation of coherent THz radiation. THz radiation, which falls within the frequency range between microwave and infrared, finds utility in various domains such as imaging, spectroscopy, and materials characterisation.This study examines the interaction of two p-polarised, positively chirped laser beams, with a hot collisional plasma characterised by a slanting up density profile. This study investigates the impact of normalised THz frequency, normalised collisional frequency, chirp parameter, and incidence angle of a laser beam on the normalised THz amplitude. The amplitude of the THz signal diminishes fast in off-resonant conditions and tends towards zero as the normalised THz frequency exceeds 1.2. The normalised amplitude of the THz wave falls as the chirp parameter increases from 0.0011to0.0099, considering both the normalised THz frequency and the normalised slanting up density modulation parameter. The amplitude of the THz signal, after being normalised, is also influenced by the incident angle and the collisional frequency. In the off-resonant state, the normalised amplitude of the THz wave tends to approach zero when the collisional frequency exceeds 0.8. The objective of this study is to enhance the current knowledge regarding the estimation of the best incident oblique angle, chirp parameter, and collisional frequency to attain an energy-efficient THz source.

The determination of the propagation parameters of a laser pulse across plasma and its various effects heavily relies on the plasma density. Consequently, a ripple density plasma was employed in our study to examine the axial laser wakefield generated by the laser pulse. We have derived analytical formulas to describe this phenomenon. The longitudinal wakefield generated in both homogeneous plasma and plasma with ripple density has been computed. The investigation is under way to examine the effects of fluctuating ripple plasma density. The findings indicate that the wakefield generated expands in size with the amplification of the ripple’s amplitude. The investigation could serve as a valuable initial reference for the optimization of the laser wakefield acceleration experiment with the aim of enhancing electron acceleration.

The phenomenon of laser wakefield acceleration is one of the prominent mechanisms to accelerate electrons to very high energies within a very small propagation distance. In this study, we have chosen Sinh–Gaussian laser pulse with static magnetic field perpendicular to direction of propagation of pulse. Analytical solution for chosen electric field is obtained from a generalized differential equation of laser wake potential. Hence, expressions for wakefield and electron energy gain are also obtained. Using feasible parameters, it is observed that when laser field amplitude increases from 3.85×1011to 4.81×1011V/m, electron energy gain increases from 102.504 to 160.163 MeV in the absence of external magnetic field and 103.258 to 160.918 MeV in an external magnetic field of 40 T. So, laser field amplitude and strength of magnetic field both have direct impact on electron energy gain and enhance in energy gain can be seen. Our research will be useful for the researchers to obtain a more energy efficient electron acceleration mechanism.

In the present manuscript, we have presented a novel theoretical model to study the monochromatic terahertz (THz) generation by beating two spatial-Gaussian (SG) laser beams in the array of anharmonic upright carbon nanotubes (CNTs) present in the form of weakly coupled plasma under the influence of static magnetic and electric fields, well supported by numerical simulation and physical interpretation. We have chosen SG laser beams because these have steep gradients in their intensity, which results in stronger ponderomotive force. The nonlinear restoration force along with the strong ponderomotive, magnetic, and electric forces with surface plasmon resonance (SPR) condition ω/ωP=0.51+iυ/ωρ/εg+(ωc2/ωP2)-υ2/ωP2+2iυω/ωP2facilitates the enhancement of nonlinear current. To evaluate the SPR condition, we have assumed that all the electrons of upright CNTs in the array are oscillating in the same phase. As a result, monochromatic THz waves are expected to be emitted by the system. Most of the THz sensors and instruments are employed in the frequency range of 0.1–10 THz to use for the nondestructive evaluation technique (NDET) with the purpose of detecting structural defects in ceramics and imaging the physical structure of old heritage paintings and manuscripts. In the proposed scheme of monochromatic THz generation, we can obtain the THz radiations in a specific frequency range of 3.15–3.25 THz and hence can play a key role in NDET. The emitted monochromatic THz radiations can also be used to perform THz pump/probe experiments in biology and nanotechnology, where output THz radiation is sensitive to the phase. In addition to that, monochromatic THz radiations with symmetrical profiles have immense potential in communication services. According to the International Telecommunication Union, the monochromaticity of THz radiations plays a significant role in communication services because of higher band utilization and lower interference.

Academic research has increasingly focused on the investigation of tunable and energy-efficient terahertz (THz) generation, owing to its significant ramifications across various domains, including crystal structure refinement, military and medical research. This study selects two Hermite–Gaussian (HG) laser beams that exhibit co-propagation and possess chirped frequencies for the purpose of investigation. The laser beam exhibits contact with an undersense plasma that is devoid of collisions when subjected to a static transverse magnetic field. The interaction between laser and plasma exhibits nonlinear characteristics, leading to the production of THz radiation that demonstrates a notable degree of energy efficiency. The objective of this study is to examine the relationship between efficiency of THz conversion, normalised transverse distance, plasma frequency, and additional laser properties such as Hermite polynomial mode index (s) and frequency chirp (b). The results suggest a significant decrease in the effectiveness of THz conversion for normalised THz frequencies in off-resonant situations. The numerical value tends towards zero. An increase in the normalised THz amplitude from 0.0025 to 0.7 and a shift in the peak towards higher normalised transverse distance values are noted as the Hermite polynomial mode index is changed from 0 to 2. The normalised THz amplitude exhibits an observed increase from 0.014 to 0.6 as the chirp parameter is raised from 0.0011 to 0.0099 for s = 1. This study demonstrates the effectiveness of the proposed methodology in generating THz radiation sources that possess high intensity, variable properties, and energy efficiency. The manipulation of the chirped parameter and Hermite polynomial mode index values is employed to accomplish this.

In the present manuscript, we study a new scheme for the magnetic field enhanced strong terahertz (THz) generation by the array of anharmonic rippled carbon nanotubes (AR-CNTs). For this purpose, we propagate a Gaussian laser beam through the array of AR CNTs forested on the dielectric substrate. The AR-CNTs have been magnetized with the help of an external magnetic field applied mutually perpendicular to the direction of propagation of the Gaussian laser beam. The Gaussian laser beam interacts with the AR-CNTs to exert a nonlinear ponderomotive force on the electrons of AR-CNTs. This is responsible for the generation of nonlinear current and THz radiation. By incorporating an externally applied static magnetic field and by varying the inter-tube separation distance of AR-CNTs, the normalized THz field amplitude of the generated waves can be tuned according to the requirement of the application. We have also observed that an externally applied static magnetic field in the optimized range of 75–95 kG paves the way for the resonantly excited strong normalized THz field amplitude with higher energy efficiency.

To obtain energy-efficient electron acceleration, several Gaussian pulse profiles like Bessel-Gaussian, super-Gaussian, and cosine-Gaussian are studied analytically. In this series, we have chosen sinh-squared-Gaussian pulse profile to investigate electron acceleration and to optimize various laser pulse and plasma parameters. For this purpose, analytical solution of wake potential, wakefield, and electron energy gain by selected laser pulse profile is obtained. Curves are plotted to discuss and compare the analytical results. The findings indicate that the wake potential, wakefield, and electron energy gain are directly proportional to the square of the laser field amplitude. The increase in plasma density results in a damped oscillatory change in energy gain. The impact of pulse length and sinh-squared-Gaussian parameter on energy gain is also examined, and optimal values for these parameters are determined. The given values yield a maximum energy gain of 1.7 GeV. The results of our analytical investigation will assist researchers in selecting an appropriate pulse profile to achieve energy-efficient electron acceleration.

In the proposed theoretical analysis, we study the enhanced THz generation by using the nonlinear interaction of a Gaussian laser beam with the array of vertically aligned carbon nanotubes (VA-CNTs). The Gaussian laser propagates through the array of VA-CNTs to exert a nonlinear ponderomotive force on the electrons of VA-CNTs. The incident laser provides them with a resonant velocity at the modulation frequency ωm. As a result, the enhanced nonlinear current density is produced in the system. This enhanced nonlinear current density is further responsible for the efficient THz generation in the system. The novelty of the proposed work is the impact of dimensions of CNTs, relative permittivity of the substrate, and modulation index on the THz generation. As it is a well-known fact that water is present in the form of ice beneath the surface of the moon, and it has a THz sign at THz frequency, therefore THz generation scheme presented in the manuscript can help space scientists and researchers to detect water on the surface of the moon with more ease.

This research conducts a thorough parametric analysis to examine the complex correlation between plasma density and the effectiveness of generating terahertz (THz) waves. Gaining a comprehensive understanding of the impact of plasma density on the efficiency of THz generation is essential for the progress of THz technology. We investigate the impact of different factors on THz generation, such as plasma density, decentered parameter, and transverse distance, using numerical simulations using Sinh-Gaussian laser beams. The results of our study demonstrate that with increase in plasma density, THz generation efficiency increases with increase in plasma density and becomes almost constant for relatively high- plasma density for the selected frequency range. THz generation efficiency increases with increase in transverse distance, becomes maximum at a specific transverse distance, then decreases continuously. This study enhances the basic comprehension of THz wave generation and offers significant insights for optimising THz sources in diverse applications using Sinh-Gaussian beams.

The laser field interacting with electrons, together with the axial magnetic field, provides a distinct opportunity to investigate particle acceleration mechanisms. We provide theoretical studies and numerical simulations to comprehend the dynamics of electron acceleration in these circumstances. The results demonstrate the important influence of laser electric field, laser pulse length, initial momentum of electron and initial direction of propagation of electron on altering the energy of the accelerated electrons. In our study, electrons of 479.02 MeV are obtained. The study explores the complex relationship of laser fields and charged particles, which could lead to innovative methods in particle acceleration and high-energy physics.

Laser wakefield acceleration (LWFA) has surfaced as a potentially effective method for generating electron beams with significant energy. The objective of this study is to examine the influence of a transverse static magnetic field on LWFA in a homogeneous plasma medium utilizing Hermite–Gaussian laser pulse. This study utilizes comprehensive theoretical studies and numerical simulations to examine the relationship between the properties of Hermite–Gaussian laser pulses, the strength of the transverse static magnetic field, and their combined effect on wakefield excitation. With the increase in external magnetic field from 0 to 40 T (1 Tesla = 10 kilogauss), generated laser wakes potential increases from 7.63 to 11.07 kV, while the generated laser wakefield increases from 0.65 to 0.94 GeV/m for laser field amplitude 4.3×1010V/m. The knowledge acquired from this research enhances the collective comprehension of the complex interconnections that exist between magnetic fields and Hermite–Gaussian laser pulses. The results of this study hold significance for the development and enhancement of forthcoming experiments that seek to fully exploit the capabilities of LWFA for a range of purposes, such as compact particle accelerators and particle physics research.

IMPORTANCE: Symptomatic oral lichen planus (OLP) can be challenging to treat. OBJECTIVE: To compare the efficacy of oral acitretin plus topical triamcinolone acetonide (TAC), 0.1%, with TAC monotherapy in patients with symptomatic OLP. DESIGN, SETTING, AND PARTICIPANTS: This monocentric, investigator-initiated, placebo-controlled, investigator- and patient-blinded randomized clinical trial was conducted from December 2018 to June 2020 at the Postgraduate Institute of Medical Education and Research, a tertiary referral center in Chandigarh, India. Sixty-four patients 18 years or older with symptomatic OLP were recruited by consecutive sampling. Data were analyzed from July to December 2020. INTERVENTION: The patients were randomized to receive either a combination of oral acitretin (25-35 mg/d) and TAC (treatment group) or TAC in combination with placebo (placebo group) for 28 weeks, with an additional 8 weeks of treatment-free follow-up after the end of treatment (36 weeks of total study duration). MAIN OUTCOMES AND MEASURES: The disease severity and treatment response were assessed using Oral Disease Severity Score (ODSS), Oral Health Impact Profile 14 (OHIP-14), and visual analog scale (VAS). The primary aim was to assess the number of patients achieving ODSS-75 (75% reduction in ODSS compared with baseline) in both groups at 28 weeks and at the end of 36 weeks. RESULTS: Among 64 patients, 31 in the treatment group and 30 in the placebo group completed the study (mean [SD] age, 50.6 [15.2] years vs 49.2 [14.4] years; male-female ratio, 13:19 vs 16:16). Baseline ODSS, visual analog scale, and Oral Health Impact Profile 14 scores were comparable in both groups. In the intention-to-treat analysis, there was a statistically significant higher number of patients achieving 75% or higher reduction in ODSS in the treatment group compared with the placebo group at the end of 28 weeks (28 [88%] vs 15 [47%], a 41 [95% CI, 20-61] percentage point difference between groups; P < .001; Cramér V = 0.47) and 36 weeks (27 [84%] vs 13 [41%], a 43 [95% CI, 23-67] percentage point difference between groups; P < .001; Cramér V = 0.47). Relapses during the posttreatment follow-up of 8 weeks were low among patients in both treatment and placebo groups (1 [3%] vs 2 [6%], a 3 [95% CI, −13 to 7] percentage point difference between groups; P > .99; Cramér V = 0.07). CONCLUSION AND RELEVANCE: In this randomized clinical trial, the combination of oral acitretin and TAC was more effective than TAC monotherapy in patients with symptomatic OLP. TRIAL REGISTRATION: Clinical Trial Registry of India Identifier: CTRI/2018/11/016448

In recent years, terahertz (THz) radiation has become an extremely useful instrument in a variety of domains, including spectroscopy, imaging, and communication, due to its exceptional qualities. In this paper, we analyse the creation of THz radiation by employing two Sinh-Gaussian chirped laser pulse profile in homogeneous collisionless plasma. Nonlinear ponderomotive force developed due to this propagation in studied analytically and expression for nonlinear current density is derived. This nonlinear current density is responsible for THz generation. Role of decentered parameter, frequency chirp parameter and transverse distance is studied and concluded that with increase in decentered parameter and transverse distance, THz efficiency increases while decreases with increase in positive frequency chirp parameter. Our findings elucidate optimal conditions for maximizing THz output power and spectral bandwidth, providing valuable insights for the design and optimization of THz sources based on chirped laser pulses.

This work investigates the acceleration of electrons in a homogeneous magnetized plasma that is both cold and collisionless. We obtained an increase in energy by stimulating laser wakefield excitation using a cosh-Gaussian laser pulse. The analysis shows a significant rise in both wakefield excitation and maximum gain in electron energy with increasing pulse strength. The amount of the external magnetic field, pulse length, and parameter w0are essential for achieving higher acceleration and a greater amplitude wakefield, together with pulse intensity. By carefully adjusting these various parameters, we can create a very powerful wakefield for accelerating electrons. By utilizing precise normalized parameters, we have successfully attained an energy gain of up to 433.80 MeV in this study. The findings of this study on laser-driven electron acceleration may be valuable for researchers involved in the rapidly advancing field of laser science and technology.

Laser wakefield acceleration is a highly promising technique for tiny particle accelerators that show potential for use in a range of scientific and medical disciplines. This study aims to explore the augmentation of laser wakefield acceleration by deliberately manipulating magnetic fields in weakly relativistic regime. More precisely, we utilize a cosh-squared Gaussian pulse to manipulate the laser intensity distribution, with the goal of enhancing the interaction between the laser and the plasma medium. Through theoretical analyses, we explore the impact of the cosh-squared Gaussian pulse on the formation and propagation of the laser wakefield, as well as its subsequent effects on electron acceleration. Furthermore, we introduce a controlled magnetic field into the system, strategically manipulating its strength and orientation to augment the acceleration process. The interplay between the modified laser pulse and the magnetic field is investigated to elucidate the underlying physics governing enhanced particle acceleration. This research contributes valuable insights into the fundamental mechanisms governing laser–plasma interactions and opens new avenues for optimizing compact particle accelerators for diverse applications.

The optimization of laser and plasma parameters for energy-efficient electron acceleration is a challenging problem that requires a multidisciplinary approach. This method takes into consideration the features of the laser as well as the ambient conditions of the plasma medium. In this study a laser pulse of sin profile is chosen to generate laser wakefield in plasma. Analytical expressions for generated laser wake potential, wakefield and electron energy gain are obtained, and curves are plotted to compare the results. Our analytical study shows that Laser pulse strength plays a crucial role in energy gain of electrons and for a particular pulse length, an optimized plasma density is required for optimum electron energy gain and for a particular plasma density, an optimized pulse length is required for optimum electron energy gain. So, the laser parameter (laser pulse length) and plasma parameter (plasma density) have mutual connection which must be taken into account for energy efficient electron acceleration.

The phenomenon of frequency doubling at the interface of Ag-InSb and Al-InSb by self-focused Hermite–Cosh–Gaussian laser beam has been studied for two different mode-indices in the Kretschmann configuration. Surface plasma wave generated by the interaction of the laser with metal at metal–glass interface applies ponderomotive force on the electrons of semiconductor leading to harmonic generation at metal–semiconductor interface. Considering paraxial approximations, it has been found that amplitude enhancement is more in Ag-InSb. Our work shows that metal–semiconductor interface could be a good option for harmonic generation which further can be used for medical purposes.

This study investigates the impact of a density ramp on the self-focusing of q-Gaussian laser beam (q-GLB) in magnetized plasma. Utilizing the q-Gaussian distribution to capture non-Gaussian features, we derive the nonlinear differential equation governing beam width parameter evolution under Wentzel–Kramers–Brillouin (WKB) and paraxial approximations. Our findings reveal that the density ramp significantly influences laser beam propagation which results in self-trapping. However, the action is more pronounced with higher ramp parameters, showing the importance of the ramp in dynamics of the system. Furthermore, non-Gaussian properties result in the formation of multiple filaments, with the quantity of these filaments determined by the q-parameter. Density ramp combined with magnetic fields enhances self-focusing and self-trapping, yielding more efficient laser-to-plasma energy transfer. These findings have potential applications in laser-plasma-based technologies, such as particle acceleration and inertial confinement fusion.

Terahertz (THz) has emerged as a significant field of study because to its extensive practical applications in various domains such as medical diagnosis, remote sensing, defence, and short-range wireless communication, among others. Numerous endeavours have been undertaken to achieve a tuneable and energy-efficient terahertz (THz) source. This study examines the co-propagation of two Hermite-cosh-Gaussian laser pulses within an underdense plasma medium characterized by a slanting up density profile. The interaction between laser and plasma exhibits nonlinear characteristics, leading to the creation of THz radiation with high efficiency. An analytical study is conducted to examine the relationship between the conversion efficiency of terahertz (THz) waves and characteristics such as plasma frequency, Hermite polynomial mode index (s), decentred parameter (b), and electron collisional frequency (γen). The results show that as we move in off-resonant direction, THz conversion efficiency decreases and becomes almost zero for normalized THz frequency and normalized collisional frequency values >1.6and >4, respectively. THz conversion efficiency increases with increase in Hermite polynomial mode index values for s=0,1,2. The suggested method is particularly useful for producing high intensity, tuneable, energy-efficient THz radiation source by adjusting the value of decentred parameter and Hermite polynomial mode index values.

Charge particles can be accelerated to extremely high energies through a phenomenon called laser wakefield acceleration. The wakefield produced by such accelerators depends on several laser and plasma characteristics. The asymmetry in the frequency chirped laser pulses we employed in this study is created by altering the pulse rise and fall times. Longitudinal wakefield and wake potential produced by asymmetric positive chirped pulses (APCP), asymmetric negative chirped pulses, (ANCP) and asymmetric unchirped pulses (AUCP) are estimated for different pulse rise and fall lengths. The curves created are used to compare the results. Findings suggest that the pulse rising time plays a significant role in wakefield generation. APCP with a shorter rise length is more effective than one with a longer rise length. Furthermore, compared to NPCP, APCP can significantly improve wakefield for a given rise length. For laser pulses with unusually long rise times, frequency chirping has no discernible effect on wakefield formation. The wakefield rises with decreasing pulse rise length (increasing pulse fall length) for the same chirp and pulse length. Wakefield rises with an increase in the positive chirp parameter b and drops with an increase in the negative chirp for the same pulse rise duration. This study has practical implications for researchers seeking to identify an optimal laser pulse for generating laser–plasma interaction that is both effective and energy efficient.

Terahertz (THz) has become a prominent area of research because of its wide-ranging practical applications in sectors such as cancer detection, biochemical sensors, and unmanned aerial vehicles. Various initiatives have been pursued to develop a customisable and energy-efficient terahertz (THz) source. This work investigates the simultaneous propagation of two Hermite–Gaussian (HG) laser pulses within a collisional plasma medium with slanting up density profile. The laser–plasma interaction displays nonlinear properties, resulting in the generation of highly efficient THz radiation. A comprehensive analysis is performed to investigate the correlation between the effectiveness of converting terahertz (THz) waves and several factors, including plasma frequency, Hermite polynomial mode index (s), and electron collisional frequency. The findings indicate that when we deviate from the resonant direction, the efficiency of converting THz waves diminishes and reaches nearly zero when the normalized THz frequency exceeds 1.6 and the normalized collisional frequency exceeds 3.5. The conversion efficiency in the terahertz range grows as the Hermite polynomial mode index values increase for s= 0, 1, 2. The proposed technique is highly effective in generating intense, adjustable, and energy-efficient THz radiation by manipulating the Hermite polynomial mode index values.

Particle accelerators play a crucial role in modern scientific research, facilitating progress in diverse areas such as fundamental physics and medical treatments. In this study, an intense Sinh-Gaussian laser pulse propagating through vacuum is investigated. Various laser pulse parameters like laser intensity, decentered parameter, and laser beam radius and their impact on electron acceleration is investigated. Our research outcomes show that electron energy gain increases significantly with laser beam intensity and decentered parameter but decreases with laser beam radius. By using suitable parameters, electrons of a maximum of 1.21 GeV energy are obtained in this study. The investigation of energy efficient direct electron acceleration presents the opportunity to explore hitherto unexplored areas of scientific inquiry and technological progress.

Terahertz (THz) research has gained prominence because to its diverse practical applications in areas including early cancer detection, oral tissue detection, concealed objects detection, food safety and quality inspection, bacteria detection and burn diagnosis. Several efforts have been made to create a customizable and energy-efficient terahertz (THz) generator. This study examines the concurrent transmission of two Hermite-Gaussian (HG) laser pulses in a collisional homogeneous plasma medium. Laser-plasma interaction exhibits nonlinear characteristics, leading to the production of extremely effective THz radiation. An in-depth investigation is conducted to study the relationship between the efficiency of converting terahertz (THz) waves and various parameters such as plasma frequency, Hermite polynomial mode index (s), and electron collisional frequency. Deviation from the resonant direction leads to a decrease in the efficiency of converting THz waves. Efficiency drops to almost zero when the normalized THz frequency surpasses 1.8 and the normalized collisional frequency goes above 4. This study achieves normalised THz amplitude nearly 0.9 and 0.15 for normalised THz frequency and normalised collisional frequency, respectively. Conversion efficiency in the terahertz band increases with higher Hermite polynomial mode index values for s = 0,1,2. The suggested method efficiently produces powerful, customizable, and energy-saving THz radiation by controlling the Hermite polynomial mode index values.

This paper presents a comparative analysis of laser wakefield acceleration (LWFA) generated by three different laser systems; Ti: Sapphire, Nd: YAG, and CO2lasers, operating under identical conditions. Laser wakefield acceleration, a promising technique for compact particle acceleration, relies on the interaction of intense laser pulses with a plasma medium to generate high-energy electron beams. By conducting an analytical study with three distinct laser systems at similar plasma parameters, we aim to investigate the influence of laser wavelength on the resulting electron beam characteristics. Our findings reveal a significant increase in the wake potential, wakefield and electron energy gain produced by each laser system with the increase in the wavelength of used laser pulse. This comparative analytical study provides valuable insights into optimizing laser parameters for tailored electron beam generation in laser wakefield acceleration experiments.

The properties of the wakefield and the resulting accelerated particle bunch are significantly influenced by the pulse profile of the driving laser. The current research investigates the intricate connection that exists between the pulse profile of the laser and the subsequent acceleration of electrons during the process known as laser wakefield acceleration (LWFA). A theoretical comparison of the acceleration of electrons in laser wakefield acceleration using Gaussian and cosh-squared-Gaussian laser pulses is the focus of this article. For both of the pulses, analytical formulas are obtained for the generated laser wake potential, wakefield, and energy gain. Comparisons are made between the various numerical values of these quantities that correlate to various parameters. According to the findings we obtained, the cosh-squared-Gaussian (csG) pulse possesses a unique intensity profile that has been flattened, which allows it to successfully accelerate electrons. A maximum energy increase of 5.19 GeV can be achieved by employing a csG laser pulse with parameters that are amenable to experimentation. By analyzing the impacts of various types of laser pulses, the purpose of this research is to provide a thorough knowledge of the fundamental concepts behind laser wakefield acceleration.

A systematic numerical study on terahertz (THz) radiation by the interaction of laser with under-dense plasma with the inclusion of a variety of laser and plasma parameters is reported in the present communication. We have included the effect of the externally applied transverse magnetostatic field on the THz generation scheme reported by Mehta et al. (Laser Phys. Lett. 15(1):045403, 2019) in 2019. The externally applied magnetostatic field can be utilized to enhance the nonlinear coupling present between the plasma and electromagnetic waves as well as to control the various parameters of the emitted energy-efficient THz radiations. We demonstrate that the resonance attributed to nonlinear effects and broadening the emission spectra significantly can be tuned by varying the value of the externally applied magnetostatic field on the p-polarized laser pulses.

Energy enhancement of electrons is a promising field of research due to its application in various fields of scientific research. The role of various parameters like plasma density, frequency chirp, laser pulse length and external magnetic field, etc., are studied and optimized for the enhancement of energy gain and energy efficiency of the acceleration scheme. In the recent study, we have chosen a novel laser pulse profile, i.e., sinh-squared-Gaussian laser pulse to study the effect of laser electric field and externally applied transverse static magnetic field. The generated laser wake potential, wakefield, and electron energy gain have a positive correlation with laser electric field strength and the strength of the external magnetic field. In our study, with an increase in magnetic field from 0 to 40 T (1 Tesla = 10 kilogauss) and laser electric field of 4.81×1011V/m, generated wake potential increases from 164 to 183.59 kV, laser wakefield increases from 6.18 to 6.91 GV/m, and electron energy gain increases from 162.98 to 182.45 MeV. Our research will contribute to the development of a novel scenario for the augmentation of electron energy using magnetic fields.

The paper investigates the phenomenon of laser wakefield acceleration in a collisionless underdense plasma using Hermite–Gaussian laser pulses. Laser wakefield acceleration is a promising method to generate high-energy particle beams over short distances. The study focuses on utilizing Hermite–Gaussian laser pulses, which have a unique intensity distribution, to drive the wakefield and accelerate electrons effectively. Through theoretical analysis, the paper explores the intricate interplay between the laser pulse's characteristics, the resulting laser wakefield structure, and the electron energy gain. In our research, we revealed that the electron energy gain rises as the amplitude of the laser pulse increases irrespective of Hermite mode index (s). Under identical conditions, we observed enhanced energy gain for s = 0 and s = 2 mode indexes than for s = 1 mode. Electron energy gain varies with pulse length, plasma density, and beam waist for a given Hermite mode index. As a result, the optimized value of any one parameter for maximum energy gain fluctuates with the corresponding values of the other two parameters as well. We have successfully obtained an energy gain of 2.65 GeV with a selected set of parameters. The findings shed light on the potential of Hermite–Gaussian laser pulses in enhancing the performance of laser wakefield acceleration setups, offering insights into optimizing the generation of high-energy particle beams for various applications, such as particle physics experiments and medical treatments.

The effects of two parallel Cosh-Gaussian laser beat waves on electron acceleration in vacuum have been investigated. By using a Cosh-Gaussian (ChG) laser instead of a Gaussian laser, we can achieve higher electron energies. To verify how laser intensities and other parameters affect electron energy, we have also examined the impact of frequency chirp for effective electron acceleration. ChG lasers are excellent for electron acceleration in vacuum due to their special characteristics, including non-diffracting behavior, controlled acceleration gradients, and minimized space charge effects. High-quality, high-energy electron beams can be produced using these lasers for a variety of purposes, such as particle physics research, imaging in medicine, and industrial uses. The electron and laser field can exchange resonant energy due to the chirp-induced phase matching condition. Depending on the chirp properties, the electron may acquire or lose energy. With the use of chirp mechanism, we can achieve more energy gain comparing to without chirp, as the presence of chirp aids in increasing the interaction period between the electron and the laser. Chirped laser pulses help to achieve phase matching between the laser field and accelerated electrons and allow precise control over the electron trajectories. Chirped pulses also help to mitigate the energy spread of the accelerated electrons. We also demonstrated interference at focus in this manuscript caused by two parallel propagated coherent lasers in the z axis, which aids in electron acceleration, resulting higher energy of electron in z-direction. The laser beam width in the transverse direction (perpendicular to the beam propagation) plays a role in focusing the laser field onto the interaction region with the electrons. The chirp and laser beam width of each laser is carefully controlled and synchronized to achieve the desired electron acceleration outcome.

Second-harmonic generation (SHG) induced by surface plasma waves (SPW) on three different metal–semiconductor interfaces has been analyzed using Kretschmann attenuated total reflection configuration. The interaction between laser and metal generates surface plasma waves (SPW) which could further influence the charge carriers of semiconductor, coated above metal. The nonlinear interactions governed by ponderomotive force lead to harmonic generation. The presence of density ripple on metal surface supports the interactions and helps in phase matching. Under given conditions, Cu–InSb gives better output. This model could provide a cost-effective method for efficient second-harmonic generation which could be useful for medical purposes.

Rainfall prediction has been of utmost importance in any country. The amount of rainfall in a particular region has been known to affect the growth in that area, especially in an agriculture-based country like India. This paper proposes a model which performs one step rainfall forecasting in the regions Ranakpur and North-Eastern states of Assam and Meghalaya based on time series data acquired from 1 and 75 weather stations in both areas, respectively. This model was chosen to be based on the LSTM algorithm which has proven to be better than existing rainfall prediction models based on linear regression, support vector regressors, artificial neural network, random forest and decision tree algorithms. The RMSE score of the proposed architecture for Ranakpur and North-East were 1.948 and 2.654 respectively, better than the algorithms used in comparison. The factors taken into consideration for while predicting the weather are max temperature, min temperature, precipitation, wind speed, relative humidity and solar radiation.

A theoretical scheme of terahertz (THz) generation by the nonlinear mixing of obliquely incident laser beams in the closely-packed assemblage of anharmonic upright carbon nanotubes (CNTs) is examined. In the scheme, anharmonicity is explained on the basis of the nonlinear variation of restoration force on the electrons of upright CNTs and it is observed to play a pivotal role in the enhancement of THz generation. The laser beams incident obliquely at some angle ′θ′on the closely-packed assemblage of upright CNTs forested over the non-conductive sapphire or silicon on sapphire (SOS) substrate so that each upright CNT of the assemblage exhibits the oscillatory behavior. The proposed scheme is quite suitable for generating efficient THz radiations at optimized values of the laser beams, plasma, and CNTs parameters. The absorption of obliquely incident laser beams by the closely-packed assemblage of upright CNTs is observed to attain its peak at the specific angle of incidence known as the critical angle and in the present scheme it is θ=44.3o. We also explore the impact of interior radius, exterior radius, critical angle, and length of CNTs and some other related parameters with energy efficiency on the THz generation.

Recently, co-propagating two-color laser pulses have been extensively used to study the attosecond pulse generation, for controlling the electron motion at femtosecond and attosecond time scales, for high harmonic generation in solids and gases, etc. In this paper, we have studied the co-propagational effect of two Gaussian laser pulses of different pulse length and frequency (ω1≈2ωpand ω2≈ωp) through under-dense plasma. Plasma density satisfies the condition of beating to generate maximum wakefield, i.e., the difference of frequency is equal to the frequency of first pulse and equal to plasma frequency (ω1-ω2≈ωp)also. Longitudinal force on electron and laser wakefield developed in plasma are studied analytically. Under the above-stated conditions, approximately 6 times stronger longitudinal force is experienced by the electrons as compared to individual single pulse. An enhanced laser wakefield has also been observed. This study is carried out for optimizing the parameters of lasers and plasma medium to maximize the electron energy gain.