220 research outputs found
Laser Requirements for High-Order Harmonic Generation by Relativistic Plasma Singularities
No full textWe discuss requirements on relativistic-irradiance (I0 > 1018 W/cm2) high-power (multi-terawatt) ultrashort (femtosecond) lasers for efficient generation of high-order harmonics in gas jet targets in a new regime discovered recently (Pirozhkov et al., 2012). Here, we present the results of several experimental campaigns performed with different irradiances, analyse the obtained results and derive the required laser parameters. In particular, we found that the root mean square (RMS) wavefront error should be smaller than ~100 nm (~λ/8). Further, the angular dispersion should be kept considerably smaller than the diffraction divergence, i.e., μrad level for 100–300-mm beam diameters. The corresponding angular chirp should not exceed 10−2 μrad/nm for a 40-nm bandwidth. We show the status of the J-KAREN-P laser (Kiriyama et al., 2015; Pirozhkov et al., 2017) and report on the progress towards satisfying these requirements
Optical probing of relativistic plasma singularities
No full textSingularities in multi-stream flows of relativistic plasmas can efficiently produce coherent high-frequency radiation, as exemplified in the concepts of the Relativistic Flying Mirror [Bulanov et al., Phys. Rev. Lett. 91, 085001 (2003)] and Burst Intensification by Singularity Emitting Radiation [Pirozhkov et al., Sci. Rep. 7, 17968 (2017)]. Direct observation of these singularities is challenging due to their extreme sharpness (tens of nanometers), relativistic velocity, and transient non-local nature. We propose to use an ultrafast (a few light cycles) optical probe for identifying relativistic plasma singularities. Our estimations and Particle-in-Cell simulations show that this diagnostic is feasible
Laser Requirements for High-Order Harmonic Generation by Relativistic Plasma Singularities
No full textWe discuss requirements on relativistic-irradiance (I0 > 10^18 W/cm^2) high-power (multi-terawatt) ultrashort (femtosecond) lasers for efficient generation of high-order harmonics in gas jet targets in a new regime discovered recently (Pirozhkov et al., 2012). Here, we present the results of several experimental campaigns performed with different irradiances, analyse the obtained results and derive the required laser parameters. In particular, we found that the root mean square (RMS) wavefront error should be smaller than ~100 nm (~λ/8). Further, the angular dispersion should be kept considerably smaller than the diffraction divergence, i.e., μrad level for 100–300-mm beam diameters. The corresponding angular chirp should not exceed 10^−2 μrad/nm for a 40-nm bandwidth. We show the status of the J-KAREN-P laser (Kiriyama et al., 2015; Pirozhkov et al., 2017) and report on the progress towards satisfying these requirements.journal articl
Relativistic plasma singularities and BISER
No full textI will talk about relativistic plasma singularities created by ultra-intense lasers, and coherent x-ray emission from these singularities: the BISER effect.Christmas High Power Laser Science Community Meetingconference objec
BISER enhancement with Astra laser
No full textBurst Intensification by Singularity Emitting Radiation (BISER) [1] is the phenomenon of extremely bright coherent wave emission (constructive interference, N^2 effect) by singularities of multi-stream flows. High-power femtosecond lasers can produce such flows and corresponding relativistic plasma singularities in underdense plasma; these singularities emit very bright coherent x-rays [2]-[3]. We have recently performed an experiment on BISER coherent x-ray generation with the Astra Laser in the CLF RAL, UK. We observed BISER coherent soft x-rays with two spectrographs: a three-channel flat field spectrograph [4] in the forward direction (channels at -0.6, 0, and 0.8°) operating in the 17-34 nm range and a normal-incidence imaging spectrograph [5] in a 10° off-axis direction operating in the 12.4-20 nm range. Both spectrographs, in addition, provided data on the angular distribution of the BISER radiation. We took advantage of an extensive experiment term and long daily laser operation hours to optimize the laser (in particular, focal spot, which is a necessary prerequisite for BISER [6], and pulse width) and the experimental conditions (in particular, the density profile). These resulted in ~2 orders of magnitude enhancement in BISER photon number, providing >10^11 photons and >μJ energies per pulse in each channel at 7 TW laser power, the result which could previously be obtained at >100 TW laser power only.
We acknowledge support from the Astra Laser Group and the CLF Target Fab, Mechanical, and Electrical. Financial support: JSPS Kakenhi JP 19KK0355 and 19H00669, CLF, Russian Science Foundation (20-62-46050), IAP RAS, ELI-Beamlines, the Ministry of Education, Youth and Sports of the Czech Republic by the project "Advanced Research Using High Intensity Laser Produced Photons and Particles" (CZ.02.1.01/0.0/0.0/16_019/0000789), and the QST Director Fund 創成的研究 #20.
[1] A. Pirozhkov, T. Esirkepov et al., "Burst intensification by singularity emitting radiation in multi-stream flows," Sci. Rep. 7, 17968 (2017).
[2] A. S. Pirozhkov et al. "Soft-X-Ray Harmonic Comb from Relativistic Electron Spikes" PRL 108 135004 (2012)
[3] A. S. Pirozhkov et al., "High order harmonics from relativistic electron spikes" New J. Phys. 16, 093003 (2014).
[4] D. Neely et al., "A multi-channel soft X-ray flat-field spectrometer," AIP Conf. Proc. 426, 479 (1998).
[5] A. Shatokhin et al., "High-resolution stigmatic spectrograph for a wavelength range of 12.5-30 nm," Opt. Express 26 19009 (2018).
[6] A. S. Pirozhkov, et al. "Laser Requirements for High-Order Harmonic Generation by Relativistic Plasma Singularities," Quantum Beam Sci. 2, 7 (2018).Annual meeting of the JSAPconference objec
BISER X-ray structures in ultraintense laser-plasma interactions
No full textIn the last two decades the regime of ultraintense (>1019 Wcm-2) laser pulses producing and interacting with plasma has revealed unprecedented advancements in particle acceleration and as a secondary source of high-energy radiation beams.
Previous experiments, developed in our group, have discovered coherent x-ray beams with high brightness (approaching that of FELs1) and composed of multiple high order harmonics2,3. The following experiments and simulations have shown that the produced x-ray sources are from tens to hundreds of nanometers in size. This novel phenomenon is known as BISER4.
Here, we report new experimental results concerning spatial distribution of these promising x-ray sources, which will enable a more rigorous understanding of the underpinning physics of its origin and the effect of specific laser parameters on its spatial pattern and brightness. Additionally, a potential alternative technique to measure their spatial distribution with a few hundred nanometers resolution is presented, which will enable both, the estimation of the source size and its brightness.
[1] C. Pellegrini and J. Stohr, Nucl. Instrum. Meth. A, 500, 33-40, 2003.
[2] A. S. Pirozhkov et al., Physical Review Letters, 108, 135004, 2012.
[3] A. S. Pirozhkov et al., New Journal of Physics, 16, 093003, 2014.
[4] A. S. Pirozhkov, T. Esirkepov et al., Scientific Reports, 7, 17968, 2017.第2回QST国際シンポジウムに参加conference objec
Optimization of BISER via Laser and Plasma Tuning
No full text1. Introduction
Burst Intensification by Singularity Emitting Radiation (BISER) [1] is the emission of coherent traveling waves by multi-stream flow singularities. Such singularities can be produced in relativistic plasma by high-power lasers, resulting in very bright coherent x-ray emission [2],[3].
2. Experimental
We have recently performed an experiment on BISER coherent x-ray generation with the Astra Laser at the CLF RAL, UK. We extensively optimized the experimental conditions, namely the plasma density and profile, and laser spot [4] and pulse, making use of substantial beam time. This resulted in a ~2 orders of magnitude higher BISER brightness compared to earlier experiments with 10 TW lasers.
3. Results
In this presentation we discuss results from two soft x-ray spectrographs: a three-channel flat field spectrograph [5] in the forward direction (channels at −0.6, 0, and 0.8°) operating in the 17-34 nm range and a normal-incidence imaging spectrograph [6] in a 10° off-axis direction operating in the 12.4-20 nm range. Under optimum conditions, both spectrographs showed μJ and higher BISER pulse energies per shot in the corresponding spectral ranges and within their acceptance angles. This implies multi-100 μJ BISER pulses in the entire spectral range and within the full angular width.
Acknowledgement
We acknowledge support from the Astra Laser Group and the CLF Target Fab, Mechanical, and Electrical. Financial support: JSPS Kakenhi JP 19KK0355 and 19H00669, CLF, Russian Science Foundation (20-62-46050), IAP RAS, ELI-Beamlines, MŠMT by the project "Advanced Research Using High Intensity Laser Produced Photons and Particles" (CZ.02.1.01/0.0/0.0/16_019/0000789), High Field Initiative (CZ.02.1.01/0.0/0.0/15_003/0000449) from the European Regional Development Fund, and the QST Director Fund 創成的研究 #20.
References
[1]A. S. Pirozhkov, T. Zh. Esirkepov et al., "Burst intensification by singularity emitting radiation in multi-stream flows," Sci. Rep. 7, 17968 (2017).
[2]A. S. Pirozhkov, et al. "Soft-X-Ray Harmonic Comb from Relativistic Electron Spikes" PRL 108, 135004 (2012).
[3]A. S. Pirozhkov, et al., "High order harmonics from relativistic electron spikes" NJP 16, 093003 (2014).
[4]A. S. Pirozhkov, et al. "Laser Requirements for High-Order Harmonic Generation by Relativistic Plasma Singularities," Quantum Beam Sci. 2, 7 (2018).
[5]D. Neely, et al., "A multi-channel soft X-ray flat-field spectrometer," AIP Conf. Proc. 426, 479 (1998).
[6]A. N. Shatokhin, et al., "High-resolution stigmatic spectrograph for a wavelength range of 12.5-30 nm," Opt. Express 26, 19009 (2018).OPIC-2022 (ALPS-2022)conference objec
On the breaking of a plasma wave in a thermal plasma. I. The structure of the density singularity
No full textThe structure of the singularity that is formed in a relativistically large amplitude plasma wave close to the wave breaking limit is found by using a simple waterbag electron distribution function. The electron density distribution in the breaking wave has a typical “peakon” form. The maximum value of the electric field in a thermal breaking plasma is obtained and compared to the cold plasma limit. The results of computer simulations for different initial electron distribution functions are in agreement with the theoretical conclusions. The after-wavebreak regime is then examined, and a semi-analytical model of the density evolution is constructed. Finally the results of two dimensional particle in cell simulations for different initial electron distribution functions are compared, and the role of thermal effects in enhancing particle injection is noted
Review on Ultra-Short and Ultra-Intense Laser Driven High Energy Proton and Ion Beams and Their Applications
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