Optimization and stability of a high-gain harmonic generation seeded oscillator amplifier

Paraskaki, Georgia; Grattoni, Vanessa; Lang, Tino; Zemella, Johann; Faatz, B.; Hillert, W.

doi:10.1103/physrevaccelbeams.24.034801

Cited by 13 publications

(14 citation statements)

References 41 publications

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“…In addition, there are still a number of considerations that need to be addressed as we are moving towards more detailed studies for the realization of this scheme. Even though first stability studies were presented in [22], it is still crucial to study the stability of this scheme over several passes with a non-ideal electron beam, including imperfections and energy chirp effects. In addition, there are other important questions related to its implementation, such as how the repetition rate can be adjusted when experiments need a lower repetition rate, the space constraints to insert mirrors when the longitudinal dispersion required for seeding at short wavelengths is small, the requirements in terms of diagnostics for the recirculating radiation field, and realizing wavelength tunability.…”

Section: Discussionmentioning

confidence: 99%

“…In the case of burst-mode operation, there is a specific number of bunches available to build-up the peak power and stability needed to deliver seeded FEL pulses. This is not an issue when the process starts with a low repetition rate seed laser source because the steady-state regime is reached within a few passes [22] as shown in Figure 5a, but it is critical when starting from shot noise, as we show in Figure 5b. The build-up regime is marked with a green background color.…”

Section: Employing An Oscillator-based Seeding Scheme In An Accelerator In Continuous-wave or Burst-mode Operationmentioning

confidence: 96%

“…Here, we review and further discuss a scheme which can generate FEL pulses of both high peak brightness, compared to SASE, and of high average flux compared to standard seeding schemes, by generating high repetition rate seeded radiation pulses [19][20][21][22]. In this scheme, an FEL oscillator is employed and acts as a feedback system which recirculates a seed pulse, and seeds the electron bunches at high repetition rate.…”

Section: Introductionmentioning

confidence: 99%

“…An HGHG seeded oscillator-amplifier starting with a low repetition rate seed laser. This scheme was discussed in detail in [22]. For the first electron bunch an external seed laser pulse is injected, and then the seed pulse is stored in the cavity.…”

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confidence: 99%

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Advanced Scheme to Generate MHz, Fully Coherent FEL Pulses at nm Wavelength

et al. 2021

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Current FEL development efforts aim at improving the control of coherence at high repetition rate while keeping the wavelength tunability. Seeding schemes, like HGHG and EEHG, allow for the generation of fully coherent FEL pulses, but the powerful external seed laser required limits the repetition rate that can be achieved. In turn, this impacts the average brightness and the amount of statistics that experiments can do. In order to solve this issue, here we take a unique approach and discuss the use of one or more optical cavities to seed the electron bunches accelerated in a superconducting linac to modulate their energy. Like standard seeding schemes, the cavity is followed by a dispersive section, which manipulates the longitudinal phase space of the electron bunches, inducing longitudinal density modulations with high harmonic content that undergo the FEL process in an amplifier placed downstream. We will discuss technical requirements for implementing these setups and their operation range based on numerical simulations.

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Section: Discussionmentioning

confidence: 99%

Section: Employing An Oscillator-based Seeding Scheme In An Accelerator In Continuous-wave or Burst-mode Operationmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Advanced Scheme to Generate MHz, Fully Coherent FEL Pulses at nm Wavelength

et al. 2021

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“…The development of both low-gain/high-Q and high-gain/low-Q oscillators is an active and ongoing area of research into FEL sources over virtually the entire electromagnetic spectrum [30,86,91,92,241,[244][245][246][247][248]. Both types of FEL oscillators have their own merits.…”

Section: Discussionmentioning

confidence: 99%

Three-Dimensional, Time-Dependent Analysis of High- and Low-Q Free-Electron Laser Oscillators

Slot

Freund

2021

Applied Sciences

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Free-electron lasers (FELs) have been designed to operate over virtually the entire electromagnetic spectrum, from microwaves through to X-rays, and in a variety of configurations, including amplifiers and oscillators. Oscillators can operate in both the low and high gain regime and are typically used to improve the spatial and temporal coherence of the light generated. We will discuss various FEL oscillators, ranging from systems with high-quality resonators combined with low-gain undulators, to systems with a low-quality resonator combined with a high-gain undulator line. The FEL gain code MINERVA and wavefront propagation code OPC are used to model the FEL interaction within the undulator and the propagation in the remainder of the oscillator, respectively. We will not only include experimental data for the various systems for comparison when available, but also present, for selected cases, how the two codes can be used to study the effect of mirror aberrations and thermal mirror deformation on FEL performance.

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