Overview of the Spallation Neutron Source Linac Low-Level RF Control System

This paper describes the Klystron RF systems for the Indiana University Low Energy Neutron Source (LENS) accelerator 425 MHz Radio Frequency Quadrupole (RFQ) and Drift Tube Linac (DTL) systems. Of interest in the power conditioning system is the design of the totem-pole grid-catch modulator for the mod-anode klystrons. This topology provides a fast rise and fall and closed loop regulation for the klystron mod-anode to cathode voltage, which minimizes RF amplitude and phase droop while maximizing efficiency. Another advantage is that short pulse high rep-rate operation is viable within the average power capabilities of the klystron. The 425 MHz, 1.25 MW klystron amplifier chain will also be detailed. Of final interest, is the digital low level RF system. This provides vector control of the cavity field using direct conversion, non-I/Q sampling architecture, at a sampling rate of 132 MHz with a 12-bit analog-to-digital converter (ADC). Four input and two output channels are integrated into a 6 unit (6U) VME module, with all DSP functions performed in Xilinx Spartan-3 field-programmable gate arrays. The design and implementation of these systems, coupled with LENS operational results, will be presented.

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“…Modern low level RF control systems often involve digital techniques [1], [2]. We make no attempt to buck that trend.…”

Section: Low Level Rf Controlsmentioning

confidence: 99%

The klystron RF systems for the indiana university lens accelerator

Reass

Rees

Derenchuk

et al. 2007

2007 IEEE Particle Accelerator Conference (PAC)

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“…If the intensity of the beam is high enough, the field can compromise the accelerating gradient in the cavity. In order to compensate for this effect, an active feed-forward system was implemented in to the LLRF system [8]. The feed-forward takes about ten pulses to learn the beam loading, and thereafter compensates for this effect.…”

Section: Front End and Warm Linacmentioning

confidence: 99%

Space charge and high intensity beam issues in the design and comissioning of the SNS accelerator

Cousineau

2006

Nuclear Instruments and Methods in Physics Research Section A:

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“…The beam loading leads to significant variation of the average bunch phase within the pulse (left picture). An adaptive feed forward compensation was added to the LLRF system [12], and as a result, the cavity field droop was flattened (right plot in Fig. 3) and the beam phase became uniform along the bunch (right picture in Fig.…”

Section: Coupled Cavity Linacmentioning

confidence: 99%

SNS machine status report

Plum

2006

Nuclear Physics B - Proceedings Supplements

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Overview of the Spallation Neutron Source Linac Low-Level RF Control System

Cited by 12 publications

References 6 publications

The klystron RF systems for the indiana university lens accelerator

The klystron RF systems for the indiana university lens accelerator

Space charge and high intensity beam issues in the design and comissioning of the SNS accelerator

SNS machine status report

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