Observations and diagnostics in high brightness beams

Cianchi, A.; Anania, M. P.; Bisesto, F.; Castellano, M.; Chiadroni, E.; Pompili, R.; Shpakov, V.

doi:10.1016/j.nima.2016.03.076

Cited by 15 publications

(25 citation statements)

References 73 publications

(36 reference statements)

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“…The QME bunch B, apart from 3.2% energy spread, sub-fs duration, and 400 nm emittance (about half of that of the reference case), has the 5-D brightness 1:1 Â 10 17 A/m 2 , preserved throughout acceleration. This is most encouraging for using the beam as a driver of a high-flux Thomson source [76].…”

Section: Stacking Suppresses Dark Currentmentioning

confidence: 77%

“…kA) e-beams [75]. To drive narrowband TS γ-ray sources, these beams have to meet some minimal requirements, such as a combination of Accelerator Physics -Radiation Safety and Applicationsa near-GeV energy with a percent-scale energy spread, a five-dimensional (5-D) brightness above 10 16 A/m 2 [76], and preferably absent low-energy background. These requirements, in combination with the kHz-scale repetition rate dictated by the applications, are clearly conflicting even for the most ambitious laser technology [77,78].…”

Section: à3mentioning

confidence: 99%

“…In the regime of our simulations, the dephasing length, defined by the etching of the head, extends by almost 80%, while the electron energy doubles against the reference case, reaching almost 900 MeV over 2.5 mm acceleration distance. Regardless of the time delay, very quiet injection keeps the e-beam brightness above 4 Â 10 16 A/m 2 , favoring the use of these beams in Thomson sources [76]. In the case of a time-delayed stack, extracting the e-beam before dephasing (using, for instance, a gas cell target of variable length [81]), thus changing the e-beam energy in the interval 400À900 MeV, preserves its 10 17 A/m 2 brightness.…”

Section: à3mentioning

confidence: 99%

“…ÀÁ À2 , the quantity defining a capability of the beam to drive a TS-based γ-ray source [76]. Here, I hi¼ Q=σ τ is the mean current; Q is the bunch charge; σ τ is the root-mean-square bunch length; and ε…”

Section: Stacking Suppresses Dark Currentmentioning

confidence: 99%

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Optically Controlled Laser-Plasma Electron Acceleration for Compact γ-Ray Sources

Kalmykov¹,

Davoine²,

Ghebregziabher³

et al. 2018

Accelerator Physics - Radiation Safety and Applications

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Thomson scattering (TS) from electron beams produced in laser-plasma accelerators may generate femtosecond pulses of quasi-monochromatic, multi-MeV photons. Scaling laws suggest that reaching the necessary GeV electron energy, with a percent-scale energy spread and five-dimensional brightness over 10 16 A/m 2 , requires acceleration in centimeter-length, tenuous plasmas (n 0 $ 10 17 cm À3 ), with petawatt-class lasers. Ultrahigh per-pulse power mandates single-shot operation, frustrating applications dependent on dosage. To generate high-quality near-GeV beams at a manageable average power (thus affording kHz repetition rate), we propose acceleration in a cavity ofelectrondensity ,drivenwithanincoherent stack of sub-Joule laser pulses through a millimeter-length, dense plasma (n 0 $ 10 19 cm À3). Blue-shifting one stack component by a considerable fraction of the carrier frequency compensates for the frequency red shift imparted by the wake. This avoids catastrophic self-compression of the optical driver and suppresses expansion of the accelerating cavity, avoiding accumulation of a massive low-energy background. In addition, the energy gain doubles compared to the predictions of scaling laws. Head-on collision of the resulting ultrabright beams with another optical pulse produces, via TS, gigawatt γ-ray pulses having a sub-20% bandwidth, over 10 6 photons in a microsteradian observation cone, and the observation cone, and the mean energy tunable up to 16 MeV.

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Section: Stacking Suppresses Dark Currentmentioning

confidence: 77%

Section: à3mentioning

confidence: 99%

Section: à3mentioning

confidence: 99%

Section: Stacking Suppresses Dark Currentmentioning

confidence: 99%

See 2 more Smart Citations

Optically Controlled Laser-Plasma Electron Acceleration for Compact γ-Ray Sources

Kalmykov¹,

Davoine²,

Ghebregziabher³

et al. 2018

Accelerator Physics - Radiation Safety and Applications

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“…By thus minimizing variations in the size of accelerating cavity, one suppresses continuous electron injection, preserving a single QME bunch with an ultrahigh five-dimensional (5D) brightness exceeding 10 16 A m -2 . Brightness in this range is clearly an advantage for the design of TS light sources [56,57]. Our simulations show that emulating a step-wise negative chirp, by advancing the higher-frequency component of the stack in time, nearly doubles electron energy compared to the predictions of the accepted scalings, demonstrating a near-GeV gain in a mm-scale, dense plasma (n 0 ∼10 19 cm −3 ) along with a boost in brightness to a few 10 17 A m -2 .…”

mentioning

confidence: 99%

Optically controlled laser–plasma electron accelerator for compact gamma-ray sources

et al. 2018

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Generating quasi-monochromatic, femtosecond γ-ray pulses via Thomson scattering (TS) demands exceptional electron beam (e-beam) quality, such as percent-scale energy spread and five-dimensional brightness over 10 16 A m -2 . We show that near-GeV e-beams with these metrics can be accelerated in a cavity of electron density, driven with an incoherent stack of Joule-scale laser pulses through a mmsize, dense plasma (n 0 ∼10 19 cm −3 ). Changing the time delay, frequency difference, and energy ratio of the stack components controls the e-beam phase space on the femtosecond scale, while the modest energy of the optical driver helps afford kHz-scale repetition rate at manageable average power. Blueshifting one stack component by a considerable fraction of the carrier frequency makes the stack immune to self-compression. This, in turn, minimizes uncontrolled variation in the cavity shape, suppressing continuous injection of ambient plasma electrons, preserving a single, ultra-bright electron bunch. In addition, weak focusing of the trailing component of the stack induces periodic injection, generating, in a single shot, a train of bunches with controllable energy spacing and femtosecond synchronization. These designer e-beams, inaccessible to conventional acceleration methods, generate, via TS, gigawatt γ-ray pulses (or multi-color pulse trains) with the mean energy in the range of interest for nuclear photonics (4-16 MeV), containing over 10 6 photons within a microsteradian-scale observation cone.The production of multi-picosecond TS γ-ray pulses has been earlier demonstrated using e-beams from conventional accelerators [12][13][14][15][16][17][18][19][20][21]. These pulses have a high degree of polarization, and are thus attractive as e-beam diagnostics [12,13]. They are also employed in the generation of polarized positrons from dense targets [15] and to demonstrate nuclear fluorescence [17][18][19]21]. Conventional accelerators, however, are large and expensive, which makes linac-based radiation sources scarce and busy user facilities. Also, the large (cm-scale) size of the radio-frequency powered acceleration cavities makes it difficult to produce and synchronize e-beams (and, hence, TS γ-ray pulses) on a sub-ps time scale relevant to high-energy density physics [22]. Luckily, an alternative technical solution, a miniature laser-plasma accelerator (LPA) [23,24], enables production of even shorter (viz. femtosecond) e-beams [25]. Besides, polychromatic (or 'comb-like') beams from an LPA, with the current modulated on a femtosecond scale, have been observed in experiments [26][27][28][29]. Simulations indicate that such beams readily lend themselves to all-optical manipulation, promising generation of spectrally controlled quasi-monochromatic, femtosecond γ-ray pulses, or trains of pulses with a femtosecond synchronization [9][10][11].LPAs, however, face a number of challenges, one of which is preservation of beam quality, that is, elimination of a high-charge, low-energy tail, which develops when acceleration is...

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Transverse emittance diagnostics for high brightness electron beams

Cianchi

Anania

Bellaveglia

et al. 2017

Nuclear Instruments and Methods in Physics Research Section A:

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Advanced diagnostic tools for high brightness electron beams are mandatory for the proper optimization of plasma-based accelerators. The accurate measurement of beam parameters at the exit of the plasma channel plays a crucial role in the fine tuning of the plasma accelerator. Electron beam diagnostics will be reviewed with emphasis on emittance measurement, which is particularly complex due to large energy spread and strong focusing of the emerging beams.

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Observations and diagnostics in high brightness beams

Cited by 15 publications

References 73 publications

Optically Controlled Laser-Plasma Electron Acceleration for Compact γ-Ray Sources

Optically Controlled Laser-Plasma Electron Acceleration for Compact γ-Ray Sources

Optically controlled laser–plasma electron accelerator for compact gamma-ray sources

Transverse emittance diagnostics for high brightness electron beams

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