A new current structure for the fast traveling-wave 2.5MeV beam chopper in the front end of the Spallation Neutron Source (SNS) has been suggested in [1]. The structure is based on the meander-folded notched stripline with dielectric supports and separators. Its design has been optimized using electromagnetic 3-D modeling with the MAFIA code package to provide rise and fall times in the range o...

High current and severe restrictions on beam losses, below 1 nA/m, in the designed linac for the National Spallation Neutron Source (NSNS) require clean and fast — with the rise time from 2% to 98% less than 2.5 ns to accommodate a 402.5-MHz beam structure — beam chopping in its front end, at the beam energy 2.5 MeV. The R&D program includes both modification of the existing LANSCE coax-plate c...

We present Chopper, a tool that efficiently explores the vast input space of file system policies to find behaviors that lead to costly performance problems. We focus specifically on block allocation, as unexpected poor layouts can lead to high tail latencies. Our approach utilizes sophisticated statistical methodologies, based on Latin Hypercube Sampling (LHS) and sensitivity analysis, to expl...

Abstract: Recuperation of braking energy offers great potential for reducing energy consumption in urban rail transit systems. The present paper develops a new control strategy with variable threshold for wayside energy storage systems (ESSs), which uses the supercapacitor as the energy storage device. First, the paper analyzes the braking curve of the train and the V-I characteristics of the s...

In low voltage low power CMOS systems the high input offset and noise voltages of MOSFETs and the moderate gain of op amps limit the accuracy of analog circuits. In this paper we summarize the results ofour recent research on the dynamic op amp matching which is a very attractive technique for the implementation of accurate analog circuits in low voltage low power CMOS systems because, in compa...

The design features of a 17 GHz chopper prebuncher injection system are described, and initial test results operating with a 500 kV low emittance electron gun and single section 17 GHz linac are presented. The 17 GHz traveling wave relativistic klystron that provides RF power to the linac structure, and the 500 kV electron gun that forms the low emittance (βγ ε = 3π mm-mradian) source for the i...

A new circuit is presented for three-phase voltage controller (AC chopper) constructed from IGBTs. Traditionally such an equipment contains thyristors as switching elements. All drawbacks of this solution come from its only possible control method: firing control. The new circuit allows Pulse Width Modulation (PWM) control, providing much better properties. A new and advantageous control method...