نوع مقاله : مقاله پژوهشی

نویسندگان

پژوهشکده پلاسما و گداخت هسته‌ای، پژوهشگاه علوم و فنون هسته‌ای، سازمان انرژی اتمی، صندوق پستی: 51113-14399، تهران- ایران

10.24200/nst.2021.1316

چکیده

در این پژوهش، شکل‌گیری موج عقبه در برهم­کنش پالس قوی لیزر با گاز با استفاده از نتایج کد شبیه­سازی PIC به­همراه یونیزاسیون بررسی شده و نتایج با حالتی که پالس لیزر در پلاسمای پیش­فرض منتشر می‌شود، مقایسه شده است. نتایج نشان می­دهند که برخلاف نتایج قبلی که به­دلیل ایجاد نوسانات چگالی هنگام یونیزاسیون، به راه­اندازی قوی ناپایداری رامان رو به جلو و به دنبال آن به مدوله شدن قوی پالس لیزر اشاره کرده بودند، اندازه میدان عقبه تولیدی در حالت انتشار پالس لیزر در گاز نسبت به پلاسما، به­شدت به شیب پالس لیزر وابسته است. علاوه بر آن برای پالس‌هایی با شیب تند، این دو مقدار تقریباً یکسان هستند. این در حالی است که برای پالس‌هایی با شیب ملایم‌تر، میدان عقبه در پلاسما دارای مقادیر بزرگ­تری بوده و برای پالس­های با شیب کم­تر، دامنه میدان عقبه در گاز بزرگ­تر می‌باشد.

کلیدواژه‌ها

عنوان مقاله [English]

Investigation of the wakefield generation in the interaction of the intense laser pulse with gas

نویسندگان [English]

  • E. Khalilzadeh
  • M.J. Jafari
  • Z. Dehghany

Plasma and Nuclear Fusion Research School, Nuclear Science and Technology Research Institute, AEOI, P.O. Box: 14399-51113, Tehran, Iran

چکیده [English]

In the present work, the formation of the wakefield during the interaction of intense laser pulse with a gas medium has been investigated by using PIC simulation code, including the ionization process. The results have been compared with those corresponding to the case of the pre-formed plasma medium. Although in previously published works, the strong launch of forwarding Raman's instability was shown to be as a result of plasma density fluctuations during ionization and the subsequent strong laser pulse modulation, our results indicate that the wakefield amplitude in gas in comparison with plasma considerably depends on the laser pulse shape. For laser pulse with a high slope, the amplitude of the wake electric field is quite the same in gas and plasma mediums. However, as the slope of the laser pulse decreases (soft slope), the wakefield is generated with a larger amplitude in the plasma. A further decrease in the laser pulse slope leads to a larger wake electric field in gas than in a plasma environment.

کلیدواژه‌ها [English]

  • Wake field
  • Laser-plasma Interaction
  • Pulse rise time
  • Raman instability
 1. J. Zhao, W.A. Schroeder, Optimization of relativistic laser self-channeling in experimental Xenon gas jet target, Plasma Physics and Controlled Fusion, 62, 045009 (2020).
 
2. MR. Edwards, JM. Mikhailova, The x-ray emission effectiveness of plasma mirrors: Reexamining power-law scaling for relativistic high-order harmonic generation, Scientific Reports, 10, 1 (2020).
 
3. T. Brümmer, et al, Design study for a compact laser-driven source for medical x-ray fluorescence imaging, Physical Review Accelerators and Beams, 23, 031601 (2020).
 
4. SY. Gus’kov, et al, The role of fast electron energy transfer in the problem of shock ignition of laser thermonuclear target, High Energy Density Physics, 36, 100835 (2020).
 
5. J. A. Marozas, et al, First Observation of Cross-Beam Energy Transfer Mitigation for Direct-Drive Inertial Confinement Fusion Implosions Using Wavelength Detuning at the National Ignition Facility, Physical Review Letters, 120, 085001 (2018).
 
6 J. Luo, et al, Multistage coupling of laser-wakefield accelerators with curved plasma channels, Physical Review Letters, 120, 154801 ( 2018).
 
7. Yx. Wang, et al, Saturation of stimulated Raman backscattering due to beam plasma instability induced by trapped electrons, Plasma Physics and Controlled Fusion, 62, 075009 (2020).
 
8. R. Wagner, et al, Electron acceleration by a laser wakefield in a relativistically self-guided channel, Physical Review Letters, 78, 3125 (1997).
 
9. A. Morozov, et al, Ionization assisted self-guiding of femtosecond laser pulses, Physics of Plasmas, 25, 053110, (2018).
 
10. W.B. Mori, T. Katsouleas, Ionization assisted self-guiding of femtosecond laser pulses, Physical Review Letters, 69, 3495 (1992).
 
11. N.E. Andreev, et al, Generation of a wakefield during gas ionization, Plasma Phys. Rep, 26, 947 (2000).
 
12. D.F. Gordon, et al, Seeding of the forward Raman instability by ionization fronts and Raman backscatter, Physical Review E, 64, 046404 (2001).
 
13. P. Kumar, et al, Simulation study of CO2 laser-plasma interactions and self-modulated wakefield acceleration, Physics of Plasmas, 26, 083106 (2019).
 
14. D.L. Fisher, T. Tajima, Enhanced Raman forward scattering, Physical Review E, 53, 1844 (1996).
 
15. D. Baue, Two-dimensional, two-electron model atom in a laser pulse: Exact treatment, single-active-electron analysis, time-dependent density-functional theory, classical calculations, and nonsequential ionization, Physical Review A, 55, 2180 (1997).
 
16. L.V. Keldysh, Ionization in the field of a strong electromagnetic wave, Soviet Physics JETP, 20, 5 (1965).
 
17. H.R. Reiss, Effect of an intense electromagnetic field on a weakly bound system, Physical Review A, 22, 1786 (1980).
 
18. D. Bauer, P. Mulser, Exact field ionization rates in the barrier-suppression regime from numerical time-dependent Schrödinger-equation calculations, Physical Review A, 59, 569 (1999).
 
19. F.H.M. Faisal, Journal of Physics B: Atomic and Molecular Physics, 6, L89 (1973).
 
20. M.V. Ammosov, N. Delone, V. P. Kraino, Tunnel ionization of complex atoms and of atomic ions in an altemating electromagnetic field, Soviet Physics  JETP, 64,  1191 (1987).
 
21. J. Derouillat, et al, Smilei: A collaborative, open-source, multi-purpose particle-in-cell code for plasma simulation, Computer Physics Communications, 222, 351-373 (2018).
 
22. W.B. Mori, The physics of the nonlinear optics of plasmas at relativistic intensities for short-pulse lasers,  IEEE J. Quantum Electron, 33, 1942 (1997).
 
23. J. Yazdanpanah, Self modulation and scattering instability of a relativistic short laser pulse in an underdense plasma, Plasma Physics and Controlled Fusion, 61, 085021 (2019).
 
24. E. Khalilzadeh, et al,  Stochastic behavior of electrons in high intensity laser–plasma interaction,  Physics of Plasmas, 22, 113115 (2015).
 
25. E. khalilzadeh, A. chakhmachi, J. Yazdanpanah, Stochastic behavior of electrons in high intensity laser–plasma interaction, Plasma Physics and Controlled Fusion, 59, 125004 (2017).
 
26. J.T. Mendonca, F. Doveil, Stochasticity in plasmas with electromagnetic waves, Physics of Plasmas, 28, 485 (1982).