Laser induced electron acceleration in the presence of static electric and magnetic fields in a plasma

Tsakiris, G. D.; Gahn, C.; Tripathi, V. K.

doi:10.1063/1.874154

Cited by 117 publications

(69 citation statements)

References 25 publications

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“…Furthermore, it is found that most of the electron energy gain is due to the transverse laser electric field with the laser magnetic field converting the transverse momentum into longitudinal one. 37,38 More recently, a similar analysis has been performed for the experiment described in Ref. 19, which in contrast to our results indicates that most of the fast electrons are produced via longitudinal acceleration due to the plasma wakefield.…”

Section: Discussionsupporting

confidence: 69%

“…19 might not have been enough time for the channel to fully develop and establish the quasi-static fields necessary for the DLA mechanism to become effective. 37,38 In recent years positrons have played an important role in applications in diverse fields of physics, e.g., surface physics, 52 positronium spectroscopy 53 and electron-positron plasmas. 54 Although for most of these applications conventional radioactive sources like 22 Na or 58 Co are currently used, the distinct possibility exists to replace them with laser driven positron sources.…”

Section: Discussionmentioning

confidence: 99%

“…A relativistic electron moving in the combined radial electric and azimuthal magnetic field executes a motion which is similar to the one in a wiggler field of a free electron laser. 38 It oscillates in the transverse direction at the betatron frequency b Ϸ p /(2␥) 1/2 in these fields while drifting along the channel together with the laser pulse. When the frequency of betatron oscillations coincides with the Doppler shifted laser frequency, as seen by the relativistic electron, a resonance occurs, leading to an effective energy exchange between the laser and the electron.…”

Section: B Electron Accelerationmentioning

confidence: 99%

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Generation of MeV electrons and positrons with femtosecond pulses from a table-top laser system

Gahn¹,

Tsakiris²,

Pretzler³

et al. 2002

Physics of Plasmas

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In experiments, the feasibility was demonstrated of generating multi-MeV electrons in a form of a collimated beam utilizing a table-top laser system delivering 200 fs pulses with P L ϭ1.2 TW and 10 Hz capability. The method uses the process of relativistic self-channeling in a high-density gas jet producing electron densities in the range of 3ϫ1019 -6ϫ10 20 cm Ϫ3 . In a thorough investigation, angularly resolved and absolutely calibrated electron spectra were measured and their dependence on the plasma density, laser intensity, and gas medium was studied. For the optimum electron density of n e ϭ2ϫ10 20 cm Ϫ3 the effective temperature of the electron energy distribution and the channel length exhibit a maximum of 5 MeV and 400 m respectively. The laser-energyto-MeV-electron efficiency is estimated to be 5%. In a second step, utilizing the multi-MeV electron beam anti-particles, namely positrons, were successfully generated in a 2 mm Pb converter. The average intensity of this new source of positrons is estimated to be equivalent to a radioactivity of 2ϫ10 8 Bq and it exhibits a very favorable scaling for higher laser intensities.

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Section: Discussionsupporting

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Section: B Electron Accelerationmentioning

confidence: 99%

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Generation of MeV electrons and positrons with femtosecond pulses from a table-top laser system

Gahn¹,

Tsakiris²,

Pretzler³

et al. 2002

Physics of Plasmas

Self Cite

View full text Add to dashboard Cite

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“…At highly relativistic a 0 , the spectra become more Maxwellian, with a steadily increasing effective temperature T ef f for increasing a 0 . The thermalization could be due to phase rotation of electrons once they became dephased in a plasma wave, but is also a consequence of direct laser acceleration (DLA) mechanisms [7,12]. The variation of maximum electron energy and temperature T ef f with increasing a 0 though is strongly indicative of the presence of DLA.…”

Section: Pacs Numbers: Valid Pacs Appear Herementioning

confidence: 99%

Observation of Synchrotron Radiation from Electrons Accelerated in a Petawatt-Laser-Generated Plasma Cavity

et al. 2008

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The dynamics of plasma electrons in the focus of a petawatt laser beam are studied via measurements of their x-ray synchrotron radiation. With increasing laser intensity, a forward directed beam of x-rays extending to 50 keV is observed. The measured x-rays are well described in the synchrotron asymptotic limit of electrons oscillating in a plasma channel. The critical energy of the measured synchrotron spectrum is found to scale as the maxwellian temperature of the simultaneously measured electron spectra. At low laser intensity transverse oscillations are negligible as the electrons are predominantly accelerated axially by the laser generated wakefield. At high laser intensity, electrons are directly accelerated by the laser and enter a highly radiative regime with up to 5% of their energy turned into x-rays. PACS numbers: Valid PACS appear hereThe advent of high power lasers has led to rapid progress in the field of plasma based particle acceleration [1]. In particular, the measurement of monoenergetic electron beams from wakefields generated by short lasers [2] has stimulated great interest in producing such beams and understanding their dynamics. One potential use for these compact sources of energetic particles is as a driver for novel light sources. Laser-accelerated electrons could be injected into a magnetic undulator realizing a compact tunable-energy femtosecond x-ray source synchronized to the laser. A laser-based x-ray source could be downsized further, using the self-generated magnetic and electrostatic fields of the plasma channel as a miniature undulator [3]. For electron beams of sufficiently high quality, an ion channel laser analogous to conventional free electron lasers may be feasible [4]. X-rays can also be produced in intense laser-plasma interactions by nonlinear Thomson scattering [5].Relativistic electron beams have also been measured from interactions at very high laser intensities, where electrons gain energy directly from the laser [6]. At high intensity, the ponderomotive force of the laser can expel plasma electrons leaving a positively charged ion channel. Electrons inside the channel experience a net focusing force due to the space charge and undergo oscillation at the betatron frequency ω β = ω p / √ 2γ z0 , where ω p is the plasma frequency and γ z0 is the Lorentz factor associated with the electrons motion along the plasma channel. Electrons resonant with the laser frequency can gain energy from the transverse electric field of the laser, which can be directed into longitudinal momentum through the v × B force [7]. Accelerating charges radiate electromagnetic radiation. For small betatron strength parameters a β = γ z0 r β ω β /c 1 (undulator limit), the spectrum of the radiation will be narrowly peaked about the resonant fre-is the Doppler factor and α is the angle between the direction of observation and the direction of γ z0 [8]. This highlights the interdependency of spectral and angular distributions. As a β → 1, emitted radiation also appears at harmonics of the resonant...

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“…We then verified that the SW alone is not able to accelerate electrons to energies as high as z = 200: indeed, when only keeping the SW electric field, we obtained electron energies no larger than z = 50, consistently with the trapped electron dynamics discussed above. We also considered the standard betatron acceleration [10,15]. This mechanism corresponds to retaining only the laser fields and the transverse charge separation field E CS in the equations of motion.…”

mentioning

confidence: 99%

Channeling of relativistic laser pulses in underdense plasmas and subsequent electron acceleration

Naseri

Pesme

Rozmus

et al. 2013

EPJ Web of Conferences

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Abstract. This contribution is concerned with the nonlinear behavior of a relativistic laser pulse focused in an underdense plasma and with the subsequent generation of fast electrons. Specifically, we study the interaction of laser pulses having their intensity I 2 in the range [10 19 , 10 20 ] W/cm 2 m 2 , focused in a plasma of electron density n 0 such that the ratio n 0 /n c lies in the interval [10 −3 , 2 × 10 −2 ], n c denoting the critical density; the laser pulse power P L exceeds the critical power for laser channeling P ch . The laserplasma interaction in such conditions is investigated by means of 3D Particle in Cell (PIC) simulations. It is observed that the laser front gives rise to the excitation of a surface wave which propagates along the sharp boundaries of the electron free channel created by the laser pulse. The mechanism responsible for the generation of the fast electrons observed in the PIC simulations is then analyzed by means of a test particles code. It is thus found that the fast electrons are generated by the combination of the betatron process and of the acceleration by the surface wave. The maximum electron energy observed in the simulations with I 2 = 10 20 W/cm 2 m 2 and n 0 /n c = 2 × 10 −2 is 350 MeV.The interaction of high-energy laser pulses at relativistic intensities with underdense plasmas is an important area of research, for the studies of the fundamental aspects of the relativistic laser-plasma interaction physics, for its physical applications [1] in particle acceleration and in radiation sources, and for the fast ignition scenario [2] of the inertial confinement fusion. Several experiments, including some very recent ones [3,4] on the propagation of sub-picosecond and picosecond pulses in gas jet plasmas, have motivated the examination of basic nonlinear physical processes such as relativistic selffocusing [5], self-modulation and induced focusing [6], laser pulse channeling [7] and channel stability [8], surface wakes [9] and the electron acceleration in the evacuated channels [10]. We have studied all these processes by means of 3D PIC simulations and analytical theory.We made extensive 3D simulations for an incident laser beam characterized by the initial FWHM w 0 = 10 m, laser intensity I = 5 × 10 19 W/cm 2 , focused in a plasma of density n 0 = 10 −3 n c along the z-direction; the laser field was linearly polarized along the x-direction, its wavelength 0 was 0 = 1 m, and n c denotes the corresponding critical density. With these parameters, the laser beam power is 28 TW, and the ratio P L /P ch is P L /P ch = 1.6; P L and P ch = 1.09 P c denote the incident laser wave power and the power threshold for channeling, respectively, P c being the usual critical power for self-focusing. Figure 1 presents the numerical results obtained with the following parameters: laser pulse duration L = 400 fs, physical time sim corresponding to the PIC simulations sim = 2200 fs.In this regime, the full electron evacuation takes place very rapidly, leading to the formation of a chann...

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Laser induced electron acceleration in the presence of static electric and magnetic fields in a plasma

Cited by 117 publications

References 25 publications

Generation of MeV electrons and positrons with femtosecond pulses from a table-top laser system

Generation of MeV electrons and positrons with femtosecond pulses from a table-top laser system

Observation of Synchrotron Radiation from Electrons Accelerated in a Petawatt-Laser-Generated Plasma Cavity

Channeling of relativistic laser pulses in underdense plasmas and subsequent electron acceleration

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