Vacuum Acceleration Research Articles

Investigating q-Gaussian laser pulse dynamics for enhanced electron acceleration in vacuum

Investigating q-Gaussian laser pulse dynamics for enhanced electron acceleration in vacuum

Chirped Cosh-Gaussian Electron Acceleration in Vacuum Due to Two Lasers

Chirped Cosh-Gaussian Electron Acceleration in Vacuum Due to Two Lasers

Analysis of frequency chirping on the electron bunch acceleration during Laguerre–Gauss laser interaction

We intend to examine the impact of frequency chirping on the efficient vacuum acceleration of an electron bunch using a chirped Laguerre–Gauss (LG) laser pulse. The study demonstrates that achieving high-energy electron acceleration relies not only on significant pulse asymmetry but also on ensuring phase synchronization in the LG laser interaction. The findings highlight the feasibility of generating outgoing electron bunches with high energy and low divergence through the selection of an optimal chirping value. Furthermore, we establish that chirping the LG laser pulse facilitates the acceleration of electrons to high energy using a lower laser intensity compared to the scenario without chirping.

Radially Polarized Laser-Induced Electron Acceleration in Vacuum

Enhanced electron acceleration due to tightly focused (TF) short-intense radially polarized (RP) Gaussian laser pulse in vacuum has been investigated. An axicon optical lens is utilized to accomplish a TF laser beam. The TF-RP laser fields are truncated to fifth order in diffraction angle. The innate and attractive symmetry of the tightly focused RP laser pulse imposes the trapping of electrons in the route of the laser propagation throughout laser–electron interaction. The applied axial magnetic field further ensures the enhancement in ponderomotive strength, pushing the electron in the expediting phase up to longer distances. Utilizing the optimum parameters of RP laser and magnetic field, noteworthy augmentation in the electron acceleration up to GeV range is obtained. The electron energy gain variations are plotted and analyzed for initial laser intensity, initial phase, electron initial energy and applied magnetic field parameters.

Electron acceleration by higher-order cosh-gaussian laser pulses in vacuum

Higher-order Cosh-Gaussian (ch-G) laser pulse is proposed for effective electron acceleration and energy gain in vacuum. The intensity distribution of ch-G laser is influenced by its higher-order (m) and decentered parameter (b) controlled propagation features. The laser pulse order m= (0,1,2,3) classifies them as Gaussian, ch-G, ch-square-G, and ch-cube-G laser pulses. The flatter the beam profile becomes as the order (m) increases, with the loss of its initial maximum intensity center at a slower rate as m increases, making it suitable for long-distance propagation. The increase in decentered parameter b, changes its properties from Gaussian(b=0) to flat top (b>1) and ring-shaped (b∼2) forms. As a result, it operates well enough to quickly accelerate electrons to exceedingly high energies in a short period of time. The analytic results show that altering the m and b combination leads to a significant rise in electron energy with laser intensity (∼1020W/cm2) of the order of GeV in vacuum.

Retraction Note: Chirped laser beat wave electron acceleration in vacuum

Retraction Note: Chirped laser beat wave electron acceleration in vacuum

RETRACTED ARTICLE: Chirped laser beat wave electron acceleration in vacuum

RETRACTED ARTICLE: Chirped laser beat wave electron acceleration in vacuum

Investigation of electron acceleration in vacuum by a radially polarized laser pulse in the presence of helical wiggler field and axial magnetic field guiding

In this paper, electron acceleration by a radially polarized laser pulse in the presence of helical wiggler magnetic field and axial magnetic field has been studied. The governing equations on electron dynamics in the presence of these electric and magnetic fields were solved by the fourth order Runge-Kuta method. The effect of axial magnetic field and electron injection angle on energy gained by the electron was investigated. Numerical studies have shown that the final energy of an electron depends on the value of the magnetic field and the injection angle. It was seen that by applying a magnetic field of about 0.2 and the injection angle of about 11 degrees, the electron can gain final energy of about 3.8 GeV, which is 40 percent more than the case of zero degrees injection angle and the absence of external magnetic field.

Spatiotemporal modeling of direct acceleration with high-field terahertz pulses.

We present an improved model for electron acceleration in vacuum with high-energy THz pulses that includes spatiotemporal effects. In our calculations, we examined the acceleration with 300 GHz and 3.0 THz central frequency THz pulses with properties corresponding to common sources, and compared the Gaussian and Poisson spectral amplitudes and the associated time profiles of the electric fields. Our calculation takes into account both the longitudinal field and the spatio-spectral evolution around the focus. These aspects of the model are necessary due to the tight focusing and the duration towards a single-cycle of the THz pulses, respectively. The carrier-to-envelope phase (CEP) and the tilting angle of the coincident few- or single-cycle THz pulses must be tuned in all cases in order to optimize the acceleration scheme. We reveal additionally that electron beams with different final energies and different divergences can be generated based on simulated THz pulses having different Porras factors, describing the frequency dependence of the spatiotemporal amplitude profile, which may depend strongly on the method used to generate the single-cycle THz pulses.

Proton acceleration in vacuum using frequency-chirped laser pulses

Recent investigations demonstrate the achievement of protons with energies of several hundred MeV via vacuum laser acceleration mechanisms. However, the symmetric electric field from an unchirped laser pulse is not efficient in generating a high energy proton beam. It is known that a proton can gain energy from a chirped laser pulse through the optimal phase synchronization between the proton and the laser field. In this study, we investigate the proton acceleration by different frequency-chirped laser pulses in vacuum both analytically and numerically. We consider four different situations constituting the unchirped, linear, quadratic, and sinusoidal chirped laser pulses. For the unchirped laser case, the pulse symmetry results in no net energy gain for the proton from the laser field. Conversely, using frequency-chirped laser pulses renders high energy to the proton compared with the unchirped laser pulse. We compared three different chirped cases, and found that a sinusoidal chirped laser pulse renders maximum acceleration to the protons compared to the linear and quadratic chirped situations. There exists an optimal chirp parameter for each type of chirped laser pulse.

Efficient electron acceleration by using Hermite-cosh-Gaussian laser beam in vacuum

The electron acceleration in vacuum has been studied theoretically using a radially polarized (RP) Hermite-cosh-Gaussian (HChG) laser beam. Even if the laser’s power is low, the RP HChG laser beam is quite effective and responsible for producing high energy electron. Due to the beauty (earlier focus) of such a laser beam, it is significantly better suited to acquiring GeV order energy over short periods of time than other laser beams. The electron acceleration process is strongly influenced by two more adjustable parameters associated with this beam: decentered parameter (b) and Hermite order (s). Throughout this investigation, better trapping phenomena have been identified. The effects of changing the intensity parameter (), the beam waist width (), the decentered parameter (b), and the order of the Hermite function on electron energy gain have been investigated.

Comparison of different laser pulse envelopes with frequency chirp for efficient electron acceleration in vacuum

In the present manuscript, we have investigated the effect of chirped laser pulse envelope to study electron acceleration in vacuum. For this purpose, we have chosen two different pulse shapes, i.e trapezoidal pulse envelope and Sin4 pulse envelope. Electron has been injected axially to the front of the tested envelopes. In all calculations, the front end of each pulse is presumed to have caught up with the electron at t = 0 at the coordinate origin. The relativistic Newton-Lorentz equations of motion of electron in the field of the laser pulse have been analytically and numerically solved. By optimizing laser and frequency chirp parameters, the energy gain of the order of GeV is obtained, and it has been noticed that under the similar range of phases (0 to 2π) and laser intensity parameter (a0 = 3), trapezoidal pulse envelope shows better result than Sin4 pulse envelope on effective electron acceleration in vacuum.

Comparison of Linear and Quadratic Chirp in Beat Wave Acceleration in Vacuum

Electron acceleration due to beating of two slightly different frequency LP (Linearly polarised) laser pulses with finite spot size in a vacuum has been studied. In this scheme, two lasers are incident at a point with some angle, due to beating of LP lasers constructive interference occurs. The resultant electric and magnetic field of this constructive interference helps in acceleration of pre-accelerated electron which is injected and trapped by the field. In this paper, we have seen the effect of linear and quadratic chirp on laser beat wave acceleration in vacuum and a comparison between the two is made for effective energy gain.

The ABALONE photosensor

The ABALONE is a new type of photosensor produced by PhotonLab, Inc. with cost effective mass production, robustness and high performance. This modern technology provides sensitivity to visible and UV light, exceptional radio-purity and excellent detection performance in terms of intrinsic gain, afterpulsing rate, timing resolution and single-photon sensitivity. For these reasons, the ABALONE can have many fields of application, including particle physics experiments, such as DARWIN, and medical imaging. This new hybrid photosensor, that works as light intensifier, is based on the acceleration in vacuum of photoelectrons generated in a traditional photosensor cathode and guided towards a window of scintillating material that can be read from the outside through a silicon photomultiplier. In this work we present the simulation of the ABALONE and the results from operation at room temperature. The goal of the characterization is the evaluation of the gain, the response in time and the single photoelectron spectrum as a function of the electric field and the photoelectron emission angle. Details of future tests will be also discussed.

Dual-Temperature Acceleration Radiation

We solve for a system that emits acceleration radiation at two different temperatures. The equilibrium states occur asymptotically in Planck distributions and transition non-thermally. The model is simple enough to obtain a global solution for the radiation spectrum analytically. We present it as a potentially useful model for investigation of non-thermal vacuum acceleration radiation in the presence of final(initial) asymptotic thermodynamic horizon(less) states in equilibrium.

Optimizing direct laser-driven electron acceleration and energy gain at ELI-NP

We study and discuss electron acceleration in vacuum interacting with fundamental Gaussian pulses using specific parameters relevant for the multi-PW femtosecond lasers at ELI-NP. Taking into account the characteristic properties of both linearly and circularly polarized Gaussian beams near focus we have calculated the optimal values of beam waist leading to the most energetic electrons for given laser power. The optimal beam waist at full width at half maximum correspond to few tens of wavelengths, $\Delta w_0=\left\{13,23,41\right\}\lambda_0$, for increasing laser power $P_0 = \left\{0.1,1,10\right\}$ PW. Using these optimal values we found an average energy gain of a few MeV and highest-energy electrons of about $160$ MeV in full-pulse interactions and in the GeV range in case of half-pulse interaction.

Role of laser pulse asymmetry in electron acceleration in vacuum in the presence of an axial magnetic field

The role played by temporal asymmetry in a linearly polarized laser pulse on the acceleration of an electron in vacuum in the presence of an axial magnetic field has been investigated. The temporal shapes of the laser pulses considered here are Gaussian, positive skew (sharp rise and slow fall), and negative skew (slow rise and sharp fall). Since the pulse amplitude rises sharply in the case of positive skew, the electron experiences a strong intensity gradient during its interaction with the laser pulse, which strengthens the ponderomotive force. On the other hand, the electron experiences a gradual rise in pulse amplitude for a longer time duration in the case of negative skew. The electron energy is observed to be highest for a pulse with negative skew at low laser intensities and for a pulse with positive skew at high laser intensities. In the presence of an axial magnetic field, electron energy is observed to be highest for a pulse with positive skew at both low and high laser intensities.

Complementary diagnostics of high-intensity femtosecond laser pulses via vacuum acceleration of protons and electrons

Taking advantage of complementary measurements of the characteristics of both protons and electrons accelerated by a laser in a vacuum, we propose an advanced diagnostics of the parameters of the tightly focused high-intensity femtosecond laser pulse. The laser field description is based on Stratton–Chu integrals, which allow simulating laser pulses with different spatial–temporal profiles focused by an off-axis parabolic mirror down to the diffraction limit. The free particles, whose dynamics are calculated by the test particle method, are accelerated from a rarefied gas (almost a vacuum). We analyze the dependence of the particle spectra on the laser parameters: the laser peak intensity, focal spot size, and pulse duration. The results show that diagnostics obtained by simultaneously using protons and electrons allow increasing the estimation accuracy of measuring the focal spot size and the peak intensity and thus allow evaluating the laser pulse duration in the femtosecond range. Our proposal is a response to the urgent need to measure pulse durations in the focal spot for new PW-level class lasers of super-short duration up to ∼10 to 20 fs, which clearly demonstrate a current trend in laser technology.

Quantum Fisher information in massless scalar field with a boundary

We explore the changes of Quantum Fisher information (QFI) for an uniformly accelerating atom coupling to fluctuating massless scalar field with a perfectly reflecting boundary. We first deduce the master equation that the system obeys. For the unbounded case, the vacuum fluctuation and Unruh thermal bath can rapidly degrade the QFI. However, with a boundary, the degradation, preservation, fluctuation and enhancement of QFI are dependent on the evolution time, boundary and acceleration. In addition, the existing boundary can effectively shield QFI from the influence of the vacuum fluctuation and Unruh thermal effect. Especially, the QFI seems to be unaffected by the vacuum fluctuation and acceleration when the atom is very close to the boundary. The efficient control of the boundary and acceleration can provide the feasible scheme of improving the parameter estimation precision.

Vacuum acceleration of electrons in a dynamic laser pulse.

A planar laser pulse propagating in vacuum can exhibit an extremely large ponderomotive force. This force, however, cannot impart net energy to an electron: As the pulse overtakes the electron, the initial impulse from its rising edge is completely undone by an equal and opposite impulse from its trailing edge. Here we show that planarlike "flying focus" pulses can break this symmetry, imparting relativistic energies to electrons. The intensity peak of a flying focus-a moving focal point resulting from a chirped laser pulse focused by a chromatic lens-can travel at any subluminal velocity, forward or backward. As a result, an electron can gain enough momentum in the rising edge of the intensity peak to outrun and avoid the trailing edge. Accelerating the intensity peak can further boost the momentum gain. Theory and simulations demonstrate that these dynamic intensity peaks can backwards accelerate electrons to the MeV energies required for radiation and electron diffraction probes of high energy density materials.