START-TO-END SIMULATIONS OF THE PSI 250 MeV INJECTOR TEST FACILITY

Sep 20, 2026

Uploaded by Elsa

Since 2003, PSI has investigated a Low Emittance Gun (LEG) for an XFEL facility delivering coherent, ultra-bright, ultra-short photon beams from 0.1 nm to 10 nm. Building the facility within 800 m requires demanding electron beam parameters at undulator entrance, with FEL1 and FEL2 requiring tight slice emittance, energy spread, and peak current. FEL3, covering 1–10 nm, allows more flexibility, so two gun technologies are developed. The paper presents beam dynamics and start-to-end simulations for two injector optimizations of a CTF3 RF gun based 250 MeV injector test facility.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages3

Reading Time8 min

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Abstract

Introduction

Two Injector Optimizations

Optimization of the CTF3 RF Gun

MOPC015 Proceedings of EPAC08, Genoa, Italy START-TO-END SIMULATIONS OF THE PSI 250 MeV INJECTOR TEST FACILITY Y. Kim∗ , A. Adelmann, R. J. Bakker, M. Dehler, R. Ganter, T. Garvey, A. Oppelt M. Pedrozzi, J.-Y. Raguin, L. Rivkin, V. Schlott, A. Streun, F. Stulle, and A. F. Wrulich Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland Abstract Since 2003, PSI has been investigating an advanced Low Emittance Gun (LEG) based XFEL facility to supply coherent, ultra-bright, and ultra-short photon beams covering the wavelengths from 0.1 nm to 10 nm. To build the facility within a length of 800 m, challenging beam parameters are required at the entrance of the undulators. For the ﬁrst two FEL beamlines (FEL1 and FEL2), the required normalized slice emittance, slice energy spread, and peak current are about 0.2 μm, 0.6 MeV, and 1.5 kA respectively. However, the required beam parameters for the third FEL beamline (FEL3), covering 1 nm to 10 nm, are somewhat ﬂexible. Therefore we are developing two different gun technologies. The 1 MV high gradient pulsed diode and ﬁeld emission based advanced LEG will be used for the ﬁrst two FEL beamlines, while a CTF3 gun based RF photoinjector will be used for the third FEL beamline. To test these two injector technologies, a 250 MeV injector test facility will be constructed at PSI from 2008 . In this paper, we describe beam dynamics for two different injector optimizations of the CTF3 RF gun based injector test facility. INTRODUCTION To develop technologies for an advanced low emittance gun (LEG) for the PSI-XFEL project, we have built a 500 kV pulsed diode based LEG test facility [1,2] . In addition, a new 250 MeV injector test facility will be built at PSI from 2008 to study following things; slice and projected emittance transportation along the injector, invariant envelope matching and emittance damping in a bootster linac, bunch compression and Coherent Synchrotron Radiation (CSR) effects in a chicane, slice and projected beam parameter diagnostics with two transverse deﬂecting structures (TDSs) and three FODO cells, ultra-stable RF low level system, and timing and synchronization. In the ﬁrst phase of the 250 MeV facility, a CTF3 type V gun RF photoinjector will be used. In the second phase, a1MV pulsed diode based advanced LEG will be tested. Details on the advanced LEG and its recent progress, the LEG based 250 MeV facility, and information on the PSI-XFEL project can be found in references [1–3] . Since FEL3 will supply soft X-rays from 1 nm to 10 nm, the requirements on electron beam quality are somewhat softer than those for the ﬁrst two FEL beamlines. Therefore, after optimizing the RF photoinjector parameters on the 250 MeV injector, the RF ∗ [Mail : Yujong.Kim@PSI.ch](Mail : Yujong.Kim@PSI.ch) gun will be used as a dedicated gun for the FEL3 beamline. For this beamline, we will use High-order Harmonic Generation (HHG) based seeded HGHG scheme to supply spatially as well as temporally coherent soft X-rays. To obtain low and uniform slice emittance and slice energy spread, we optimized the gun and the bunch compressor (BC) for different values of the maximum gradient in the gun cavity and the pulse length of the gun drive laser. In this paper, we describe beam dynamics and start-to-end (S2E) simulations for the two different optimizations ofthe CTF3 RF gun based 250 MeV injector test facility. TWO INJECTOR OPTIMIZATIONS Originally, the 2.5 cell CTF3 type V gun was designed to compensate beam loading effects during multi-bunch operation at the CLIC Test Facility (CTF) [4] . Since a high gradient of 100 MV/m has been already reached with a forward power of 22 MW during an RF test of the gun at CERN, we optimized the gun for a maximum gradient of 100 MV/m as shown in Fig. 1(top) . However, the gun was originally designed to be operated at 120 MV/m with 25 MW. Therefore we also optimized the gun for a gradient of 120 MV/m as shown in Fig. 1(bottom) . Optimizati

FAQs

What facility and beam purpose does this paper address?

It addresses a 250 MeV injector test facility at PSI for the PSI-XFEL project, focused on testing injector technologies to achieve the electron-beam quality needed for soft and hard FEL operations.

Why are two injector technologies developed in this work?

FEL1 and FEL2 need stringent beam parameters, while FEL3 (1–10 nm) is more flexible; therefore two different gun approaches are pursued to cover these requirements.

What are the two injector optimization cases described for the CTF3 RF gun?

The study optimizes the CTF3 V gun for two maximum gradient settings: 100 MV/m and 120 MV/m, corresponding to different layouts shown in the figures.

Sep 20, 2026

Uploaded by Elsa