Alignment Tolerances for the CLIC Decelerator

This note aims to quantify the alignment tolerances for the CLIC decelerator lattice elements by investigating the effects of wake fields and component misalignment. The tolerances comes from the requirements of transporting the entire beam through the lattice, while extracting the required amount of energy. First, we briefly discuss the beam energy spread and its effect on the beam envelope. Then, we analyze the effects of the PETS dipole wakes for a perfect machine. Finally, the effect of lattice element misalignment is studied. Beam based alignment schemes for quadrupole correction will be presented, including modifications of the schemes needed for the CLIC decelerating station. Simulations have been performed with the tracking code PLACET . The results indicate, for an energy extraction efficiency of 85%, that it would be possible to transport the entire decelerator beam through the lattice, if PETS misalignment are not larger than ~100 um and if beam based alignment methods are used for quadrupole correction

Beam-Based Alignment for the CLIC Decelerator

The CLIC Drive Beam decelerator requires the beam to be transported with very small losses. Beam-based alignment is necessary in order to achieve this, and various beam-based alignment schemes have been tested for the decelerator lattice. The decelerator beam has an energy spread of up to 90%, which impacts the performance of the alignment schemes. We have shown that Dispersion-Free-Steering works well for the decelerator lattice. However, because of the transverse focusing approach, modifications of the normal DFS schemes must be applied. Tune-up scenarios for the CLIC decelerator using beam-based alignment are also discussed

A study of Failure Modes in the CLIC Decelerator

The CLIC Drive Beam decelerator is responsible for producing the RF power for the main linacs, using Power Extraction and Transfer Structures (PETS). To provide uniform power production, the beam must be transported with very small losses. In this paper failure modes for the operation of the decelerator are investigated, and the impact on beam stability and loss levels is presented. Quadrupole failure, PETS inhibition and PETS RF break down scenarios are being considered

A Beam Driven Plasma-Wakefield Linear Collider: From Higgs Factory to Multi-TeV

Plasma wakefield acceleration (PWFA) holds much promise for advancing the energy frontier because it can potentially provide a 1000-fold or more increase in acceleration gradient with excellent power efficiency in respect with standard technologies. Most of the advances in beam-driven plasma wakefield acceleration were obtained by a UCLA/USC/SLAC collaboration working at the SLAC FFTB[ ]. These experiments have shown that plasmas can accelerate and focus both electron and positron high energy beams, and an accelerating gradient in excess of 50 GeV/m can be sustained in an 85 cm-long plasma. The FFTB experiments were essentially proof-of-principle experiments that showed the great potential of plasma accelerators. The FACET[ ] test facility at SLAC will in the period 2012-2016 further study several issues that are directly related to the applicability of PWFA to a high-energy collider, in particular two-beam acceleration where the witness beam experiences high beam loading (required for high efficiency), small energy spread and small emittance dilution (required to achieve luminosity). The PWFA-LC concept presented in this document is an attempt to find the best design that takes advantage of the PWFA, identify the critical parameters to be achieved and eventually the necessary R&D to address their feasibility. It best benefits from the extensive R&D that has been performed for conventional rf linear colliders during the last twenty years, especially ILC[ ] and CLIC[ ], with a potential for a comparably lower power consumption and cost.Comment: Submitted to the proceedings of the Snowmass Process CSS2013. Work supported in part by the U.S. Department of Energy under contract number DE-AC02-76SF0051

Beam Dynamics Issues in the CLIC Long Transfer Line

Both the main and the drive beam of the CLIC project must be transported from the central production site to the head of the main linacs over more than twenty kilometers. Over such distances chromatic error may be substantial. With long distances and large beam currents, ion-induced detuning and instabilities and multi-bunch resistive wall effects must also be considered. These effects are quantified and simulated. Based on these results, a baseline design has been established