A conceptual design is presented of a novel energy-recovering linac (ERL) facility for the development and application of the energy recovery technique to linear electron accelerators in the ...multi-turn, large current and large energy regime. The main characteristics of the powerful energy recovery linac experiment facility (PERLE) are derived from the design of the Large Hadron electron Collider, an electron beam upgrade under study for the LHC, for which it would be the key demonstrator. PERLE is thus projected as a facility to investigate efficient, high current (HC) (>10 mA) ERL operation with three re-circulation passages through newly designed SCRF cavities, at 801.58 MHz frequency, and following deceleration over another three re-circulations. In its fully equipped configuration, PERLE provides an electron beam of approximately 1 GeV energy. A physics programme possibly associated with PERLE is sketched, consisting of high precision elastic electron-proton scattering experiments, as well as photo-nuclear reactions of unprecedented intensities with up to 30 MeV photon beam energy as may be obtained using Fabry-Perot cavities. The facility has further applications as a general technology test bed that can investigate and validate novel superconducting magnets (beam induced quench tests) and superconducting RF structures (structure tests with HC beams, beam loading and transients). Besides a chapter on operation aspects, the report contains detailed considerations on the choices for the SCRF structure, optics and lattice design, solutions for arc magnets, source and injector and on further essential components. A suitable configuration derived from the here presented design concept may next be moved forward to a technical design and possibly be built by an international collaboration which is being established.
The Large Hadron Collider (LHC) at CERN is a 7 TeV proton synchrotron, with a design stored energy of 362 MJ per beam. The high-luminosity (HL-LHC) upgrade will increase this to 675 MJ per beam. In ...order to protect the superconducting magnets and other sensitive equipment from quenches and damage due to beam loss, a multilevel collimation system is needed. Detailed simulations are required to understand where particles scattered by the collimators are lost around the ring in a range of machine configurations. merlin++ is a simulation framework that has been extended to include detailed scattering physics, in order to predict local particle loss rates around the LHC ring. We compare merlin++ simulations of losses during the squeeze (the dynamic reduction of theβ function at the interaction points before the beams are put into collision) with loss maps recorded during beam squeezes for run 1 and 2 configurations. The squeeze is particularly important, as both collimator positions and quadrupole magnet currents are changed. We can then predict, using merlin++, the expected losses for the HL-LHC to ensure adequate protection of the machine.
Design and applications of an X-band hybrid photoinjector Rosenzweig, J.B.; Valloni, A.; Alesini, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2011, Letnik:
657, Številka:
1
Journal Article
Recenzirano
Odprti dostop
An INFN-LNF/UCLA/URLS collaboration is developing a hybrid photoinjector in X-band. This device is an integrated structure consisting of initial standing wave gun cells connected at the input coupler ...to a traveling wave section. This design nearly eliminates RF reflections from the SW section; further, a 90° phase shift in the accelerating field at the coupling cell gives strong velocity bunching. The current initiative in X-band follows an S-band hybrid, now proceeding to construction at LNF and high power testing/beam production measurements at UCLA. This S-band hybrid has 1.5 cell SW and 9 cell TW sections, and produces strongly compressed 3.5
MeV beam. It can be used for novel applications; here we discuss the production of an exponential energy spectrum extending from 1 to 12
MeV to simulate the effects of radiation belt environments on space-craft. It can be optionally used with a 3
m TW linac fed from RF output of the hybrid, to boost the energy to 22
MeV. While scaling the design from S-band to X-band is conceptually simple, practical limits require changes in both RF and magnetostatic designs. As the field is limited by RF breakdown to 200
MV/m peak field, the SW section must be expanded to 2.5 cells to reach 3.5
MeV; this permits flexibility in the solenoid design. We present beam dynamics simulations that show 6D phase space compensation at 7
pC: sub-0.1
mm
mrad at the emittance minimum that occurs simultaneously with a longitudinal focus of <20
fs
rms. We discuss applications ranging from multi-THz coherent radiation production to ultra-fast electron diffraction.
RF properties of a X-band hybrid photoinjector Spataro, B.; Valloni, A.; Alesini, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2011, Letnik:
657, Številka:
1
Journal Article
Recenzirano
Odprti dostop
An INFN-LNF/UCLA/SAPIENZA collaboration is developing a hybrid photoinjector in X-band. A hybrid photoinjector is a novel high brightness electron source that couples a standing wave cell cavity ...(acting as an RF gun) directly to a multi-cell travelling-wave structure. This configuration offers a number of advantages over the split standing wave/travelling-wave system. Most notably the reflected RF transient is almost completely suppressed, thus eliminating the need for a circulator and the bunch lengthening effect that occurs in the drift section of the split system. These properties allow scaling of the device to higher field and frequencies, which should dramatically improve beam brightness. The RF coupling between the standing and the traveling wave sections is accomplished in the fourth cell encountered by the beam, with the SW section electrically coupled to it on-axis. This mode of coupling is particularly advantageous, as it is accompanied by a 90° phase shift in the accelerating field, resulting in strong velocity bunching effects on the beam that reverse the usual bunch lengthening induced after the gun exit in standard 1.6 cell photoinjectors. In this scenario, from the beam dynamics point of view, it is seen that device may produce ten's of femtosecond beams at ∼3.5
MeV and the emittance compensation dynamics remains manageable even in the presence of strong compression. We present here a survey of the device characteristics. In particular we show the results of the electromagnetic simulations, a beam dynamics analysis related to the temperature tuning of the SW and TW section, and a RF characterization using bead pull and scattering coefficient measurements of a device prototype.
PDF
