Programmable radio environments parametrized by reconfigurable intelligent surfaces (RISs) are emerging as a new wireless communications paradigm, but currently used channel models for the design and analysis of signal-processing algorithms cannot include fading in manner that is faithful to underlying wave physics. To overcome this roadblock, we introduce physics-based end-to-end model RIS-par...

The proposed PEP II B factory at SLAC requires a feedback to damp out longitudinal synchrotron oscillations. A time domain, downsampled, bunch-by-bunch feedback system in which each bunch is treated as an oscillator being driven by disturbances from other bunches is presented as we review the evolution of the system design. Results from a synchrotron oscillation damping experiment conducted at ...

every year large amounts of grapes are stores in normal and cold rooms to offer off-season of grapes to the market which based on several reasons their quality and weight greatly decreases. therefore, in order to decrease the post harvest losses of grapes and selection of suitable cultivars for long time storage, this study was conducted in two experiments, one in a factorial experiment based o...

The installation of a harmonic cavity to provide bunch lengthening and thereby increase the Touschek lifetime is considered for the ESRF storage ring. Simulations with a particle tracking code have shown that for few bunch operation where the current per bunch is large – a strong lengthening already results from the coupling with the broad band impedance of the vacuum chamber. Therefore the net...

A PIC simulation of the interaction of a positive charged bunch with an e-cloud yields the wake kick from the electrons on the tail particles of the bunch. The wake is induced from a certain offset in the transverse position of the head parts of the bunch which perturbs the electron distribution. Such pre-computed wake functions of each offset part of the bunch are forming a matrix which could ...

After extraction, the damping ring (DR) bunch length is eom@essed in the RTL (Ring-To-Linac) transport line to achieve the desired linac bunch length. For this, an energy spread is induced proportional to the DR bunch length, producing large, aperture filling, horizontal beam sizes in the dispersive regions of the RTL. There, nonlinear magnetic fields and wakefields cause higher order dispersio...

Existing methods of analysing the e ect of bunch to bunch tune shifts on coupled bunch instabilities are applicable to beams with a single unstable mode, or a few non-interacting unstable modes. We present a more general approach that involves computing the eigenvalues of a reduced state matrix. The method is applied to the analysis of PEP-II longitudinal coupled bunch modes, a large number of ...

OpenDHT: A Public DHT Service

The present bunch compressor design for the NLC allows control of the final bunch length by way of changes to the horizontal betatron phase advance of the 180ƒ-turnaround arc. This adjustability requirement significantly constrains the design and cost optimization of the system and excludes the possibility of using permanent-magnet quadrupoles in the arc. To relieve this constraint, and to avoi...

Transverse wakefield kicks from misaligned accelerating structures in the SLC linac contribute significantly to emittance growth. If these kicks could be measured directly, it would be possible to align and/or steer the beam to a kick-free trajectory. In the Accelerator Structure Test Facility at SLAC, ASSET [1], the kicks due to a drive bunch are measured with a witness bunch at varying bunch ...