Impedance of finite length resistive cylinder

Krinsky, S.; Podobedov, B.; Gluckstern, R.L.

doi:10.1103/physrevstab.7.114401

Cited by 23 publications

(33 citation statements)

References 5 publications

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“…The impedance of a finite-length, resistive insert in a beam pipe has recently been studied in several reports [1][2][3][4]. To simplify this complicated problem, it is often assumed that the skin depth is smaller than the radius of the chamber and its thickness, and therefore investigations have been limited to the behavior of the impedance in a high frequency region [2,3].…”

Section: Introductionmentioning

confidence: 99%

Coupling impedances of a resistive insert in a vacuum chamber

Shobuda

Chin

Takata

2009

Phys. Rev. ST Accel. Beams

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We have developed a theory to calculate both longitudinal and transverse impedances of a resistive short (typically shorter than the chamber radius) insert with cylindrical symmetry, sandwiched by perfectly conductive chambers on both sides. It is found that unless the insert becomes extremely thin (typically a few nm for a metallic insert) the entire image current runs on the thin insert, even in the frequency range where the skin depth exceeds the insert thickness, and therefore the impedance increases drastically from the conventional resistive-wall impedance. In other words, the wakefields do not leak out of the insert unless it is extremely thin. Formulas of the impedance valid for various cases of the insert are categorized in summary.

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Section: Introductionmentioning

confidence: 99%

Coupling impedances of a resistive insert in a vacuum chamber

Shobuda

Chin

Takata

2009

Phys. Rev. ST Accel. Beams

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“…This term was found in [8] (note the difference in the definition of normalized parameters). Setting 0, one gets from (7) the well-known Green's function for unchirped beam [12]. Now let us consider the case > 0 and 1 ẑ.…”

Section: Green's Functionmentioning

confidence: 99%

Self-amplified spontaneous emission FEL with energy-chirped electron beam and its application for generation of attosecond x-ray pulses

Saldin

Schneidmiller

Yurkov

2006

Phys. Rev. ST Accel. Beams

184

109

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Influence of a linear energy chirp in the electron beam on a self-amplified spontaneous emission (SASE) Free Electron Laser (FEL) operation is studied analytically and numerically using a 1D model. Analytical results are based on the theoretical background developed by Krinsky and Huang [Phys. Rev. ST Accel. Beams 6, 050702 (2003)]. Explicit expressions for Green's functions and for output power of a SASE FEL are obtained for the high-gain linear regime in the limits of small and large energy chirp parameters. Saturation length and power versus energy chirp parameter are calculated numerically. It is shown that the effect of linear energy chirp on FEL gain is equivalent to the linear undulator tapering (or linear energy variation along the undulator). A consequence of this fact is a possibility to perfectly compensate FEL gain degradation, caused by the energy chirp, by means of the undulator tapering independently of the value of the energy chirp parameter. An application of this effect for generation of attosecond pulses from a hard x-ray FEL is proposed. Strong energy modulation within a short slice of an electron bunch is produced by a few-cycle optical laser pulse in a short undulator, placed in front of the main undulator. Gain degradation within this slice is compensated by an appropriate undulator taper while the rest of the bunch suffers from this taper and does not lase. Three-dimensional simulations predict that short (200 attoseconds) high-power (up to 100 GW) pulses can be produced in Angstrom wavelength range with a high degree of contrast. A possibility to reduce pulse duration to sub-100 attosecond scale is discussed.

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“…When the pulse becomes so short that its spectrum gets broader than the level spacing and resonant with multiple levels, especially the Rydberg manifold, δ is still different from the scattering phase shift difference, but does not vary with T . We further explore how the chaotic nature of FEL radiation [29][30][31][32][33] affects the PAD. Our analysis using the partialcoherence method [34] indicates that the PAD is between those corresponding to the coherence time and the mean pulse duration.…”

mentioning

confidence: 99%

“…As is well known, on the other hand, the temporal pulse shapes of FEL operating in the self-amplified spontaneous emission (SASE) mode fluctuate from shot to shot [29][30][31][32][33]. In order to investigate the effects of the chaotic nature, we have performed numerical experiments for EUV pulses randomly generated by the partial-coherence method [34].…”

mentioning

confidence: 99%

Competition of Resonant and Nonresonant Paths in Resonance-Enhanced Two-Photon Single Ionization of He by an Ultrashort Extreme-Ultraviolet Pulse

Ishikawa

Ueda

2012

Phys. Rev. Lett.

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We theoretically study the pulse-width dependence of the photoelectron angular distribution (PAD) from the resonance-enhanced two-photon single ionization of He by femtosecond ( 20 fs) extreme-ultraviolet pulses, based on the time-dependent perturbation theory and simulations with the full time-dependent Schrödinger equation. In particular, we focus on the competition between resonant and nonresonant ionization paths, which leads to the relative phase δ between the S and D wave packets distinct from the corresponding scattering phase shift difference. When the spectrally broadened pulse is resonant with an excited level, the competition varies with pulse width, and, therefore, δ and the PAD also change with it. On the other hand, when the Rydberg manifold is excited, δ and the PAD do not much vary with the pulse width, except for the very short-pulse regime.PACS numbers: 32.80. Rm, 32.80.Fb, 41.60.Cr, 42.65.Ky Multiphoton ionization of atoms has consistently been receiving a great deal of attention for decades (see e.g. [1][2][3][4][5][6][7][8][9][10][11]). The advent of intense extreme-ultraviolet (EUV) sources such as high-harmonic generation (HHG) and free-electron lasers (FEL) has enabled two-photon ionization (TPI) of species with a deep ionization potential such as He [12][13][14][15][16] and N 2 [17]. Upon photoionization, the continuum electron wave packet is emitted, which is a superposition of different partial waves, each with its own orbital angular momentum, intensity, and phase. Photoelectron angular distribution (PAD), nowadays extensively studied by the velocity map imaging technique (see e.g. [18,19]), contains information on the interference of these different partial waves.In this Letter, we theoretically study the pulse-widthdependence of the PAD from two-photon single ionization of He by femtosecond (fs) EUV pulses. Especially, we focus on situations where the pulse is closely resonant with an excited level, i.e., resonance-enhanced TPI. We have chosen He as a target atom for the following reasons: first, its single-electron excitation energies, e.g., 21.218 eV for 1s2p 1 P and 23.087 eV for 1s3p 1 P [20], coincide with the 13th and 15th harmonic photon energies of a Ti:Sapphire laser, respectively, and also with the typical wavelength range of EUV FELs such as the Spring-8 Compact SASE Source (SCSS) [21], the Freeelectron LASer at Hamburg (FLASH) [22], and FERMI [23]. Second, its simple electronic structure allows for exact time-dependent numerical analysis [24][25][26][27][28], in great contrast to alkali atoms.In the case of resonance-enhanced TPI, the resonant ionization path via resonant levels and the nonresonant path via nonresonant intermediate levels coexist [2]. Our results show that in the few fs regime, the competition between the two paths can be controlled by changing the pulse width when the pulse is resonant with a single excited level. The relative phase δ between the different partial waves (S and D for He) would be just the scattering phase shift difference for nonreson...

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Impedance of finite length resistive cylinder

Cited by 23 publications

References 5 publications

Coupling impedances of a resistive insert in a vacuum chamber

Coupling impedances of a resistive insert in a vacuum chamber

Self-amplified spontaneous emission FEL with energy-chirped electron beam and its application for generation of attosecond x-ray pulses

Competition of Resonant and Nonresonant Paths in Resonance-Enhanced Two-Photon Single Ionization of He by an Ultrashort Extreme-Ultraviolet Pulse

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