Options and trade-offs in linear collider design

Roßbach, J.

doi:10.1109/pac.1995.504735

Cited by 5 publications

(3 citation statements)

References 5 publications

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“…There are several Free electron lasers being constructed or proposed afterwards everywhere in the world [3] [4] [5].…”

Section: Overviewmentioning

confidence: 99%

Parameter Selection and Longitudinal Phase Space Simulation for a Single Stage X-Band FEL Driver at 250 MeV

Sun¹,

Raubenheimer²,

Wu³

2011

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Hard x-ray Free electron lasers (FEL) are being built or proposed at many accelerator laboratories as it supports wide range of applications in many aspects. Most of the hard x-ray FEL design is similar with the SLAC Linac Coherent Light Source (LCLS), which features a two (or multiple) stage bunch compression. For the first stage of the bunch compression, usually the beam is accelerated in a lower-frequency RF section (such as S-band for LCLS), and then the longitudinal phase space is linearized by a higher-frequency RF section (harmonic RF, such as X-band for LCLS). In this paper, a compact hard x-ray FEL design is proposed, which is based on X-band RF acceleration and eliminating the need of a harmonic RF. The parameter selection and relation is discussed, and the longitudinal phase space simulation is presented. OverviewFree electron lasers ( The FEL coherence condition of the electron beam in the undulators requires a large charge density, a small emittance and small energy spread. The RMS electron bunch length from the injector is in the ps scale, with a bunch charge in the range of hundreds pC to several nC, which means that the current is roughly 0.1 kA. According to the requirement from soft x-ray lasing and hard x-ray lasing, a peak current of 1 kA and 3 kA is needed respectively. Thus the bunch has to be compressed. Usually a two stage bunch compression or multipole stage bunch compression is adopted. The z-correlated energy chirp is normally established by letting the beam pass through a section of RF cavities, with a RF phase off crest. As stated above, S-band RF (3 GHz) acceleration could be applied in this section. Due to the nature of RF acceleration wave, the chirp on the bunch is not linear, but has the RF curvature on it. In order to linearize the energy chirp, a harmonic RF section with higher frequency is needed. For LCLS a short X-band RF section (12 GHz) is used which is a fourth order harmonic.The linearized bunch is then passing by a dispersive region, in which the particles with different energy have different path length. A four dipole chicane is the natural choice for the dispersive region. As the example illustrated in Figure 1, the head of the bunch has smaller energy, and gets a stronger bending kick from the dipole magnet, then has a longer path length in the dispersive region. Similarly, the tail of the bunch has larger energy and shorter path length in the dispersive region. At the exit of the dispersive region, the relative longitudinal position of the head and tail of the bunch both move to the center of the bunch, so the bunch length will be shorter. X-band FEL driverAnother way to do the bunch compression, is to eliminate the harmonic RF section, and replace the four dipole chicane by a dispersive region which has special higher order longitudinal dispersion terms. This option may have the advantage of compact size at same energy, as it only uses X-band acceleration structures which can provide a much * Electronic address:

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“…There are several Free electron lasers being constructed or proposed afterwards everywhere in the world [3] [4] [5].…”

Section: Overviewmentioning

confidence: 99%

Parameter Selection and Longitudinal Phase Space Simulation for a Single Stage X-Band FEL Driver at 250 MeV

Sun¹,

Raubenheimer²,

Wu³

2011

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“…Because a luminosity of about 10 33 cm 2 s 1 is needed due to the small cross sections of the processes of interest, all linear collider studies worldwide consider at colliding beams having vertical dimensions of 3{20 nm [16]. Beam-based alignment and correction schemes have to beadopted to bring these tiny beams into collision.…”

Section: Introductionmentioning

confidence: 99%

Cavity beam position monitors

Lorenz¹

1998

AIP Conference Proceedings

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Abstract. Beam-based alignment and feedback systems are essential for the operation of future linear colliders and free electron lasers. A certain number of beam position monitors with a resolution in the submicron range are needed at selected locations. Most beam position monitors detect the electric or the magnetic eld excited by a beam of charged particles at dierent locations around the beam pipe. In resonant monitors, however, the excitation of special eld congurations by an o-center beam is detected. These structures oer a large signal per micron displacement. This paper is an attempt to summarize the fundamental characteristics of resonant monitors, their advantages and shortcomings. Emphasis will be on the design of cylindrical cavities, in particular on the estimation of expected signals, of resolution limits and the resulting beam distortion. This includes also a short introduction into numerical methods. Fabrication, tuning, and other practical problems will be reviewed briey. Finally, some resonant devices used for beam position diagnostics will be discussed and listed.

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“…TESLA 500 is a e + e − linear collider study using superconducting Nb accelerating structures operating at 1.3 GHz [1]. Very low wakefields and a high accelerating efficiency with a gradient of 25 MV/m are major advantages of this design.…”

Section: Introductionmentioning

confidence: 99%

Study of orbit feedback systems for the TESLA Linear Collider

Lorenz

Reyzl²,

Sabah³

Proceedings of the 1997 Particle Accelerator Conference (Cat. No.97CH36167)

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In order to reduce the influence of magnet vibrations which can cause luminosity reduction in the TESLA Linear Collider, several feedback loops are planned to control the beam orbit and to keep the beams in collision. The complete control system for orbit correction can be divided into three different feedback systems: in the main linac a slow feedback system is intended to cancel perturbations in the low frequency range which are mainly due to ground motion. In the beam delivery section a fast feedback system is to be installed to compensate disturbances containing higher frequency components, mainly from pulse-to-pulse quadrupole vibrations and potentially also due to microphonics and Lorentz-force detuning in the superconducting cavities. At the interaction point a fast feedback system will keep the two beams in collision, using the beam-beamdeflection signal. The paper summarizes design studies for all three orbit correction schemes and the main components are discussed in detail.

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Options and trade-offs in linear collider design

Cited by 5 publications

References 5 publications

Parameter Selection and Longitudinal Phase Space Simulation for a Single Stage X-Band FEL Driver at 250 MeV

Parameter Selection and Longitudinal Phase Space Simulation for a Single Stage X-Band FEL Driver at 250 MeV

Cavity beam position monitors

Study of orbit feedback systems for the TESLA Linear Collider

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