ORNL, Oak Ridge, Tennessee, USA
The Spallation Neutron Source (SNS) Harp consists of 30 wires for each of the horizontal, vertical, and diagonal planes. The purpose of the harp is to measure the position, profile, and peak density of the high intensity beam coming out of the accumulator ring and going onto the spallation target. The data-acquisition hardware is now over ten years old and many of the electronics parts are obsolete. Occasionally, the electronics must be rebooted to reset the sample-and-hold circuitry. To evaluate options for a new system, the signals from the harp were studied. This paper will describe these studies’ results, the design, and initial results of the new and simpler data-acquisition system..
ORNL RAD, Oak Ridge, Tennessee, USA
ORNL, Oak Ridge, Tennessee, USA
In 2009, the Superconducting Radio Frequency (SRF) cavities at the Spallation Neutron Source (SNS) began to experience significant operational degradation [1]. The source of the degradation was found to be repeated striking of cavity surfaces with errant beam pulses. The Machine Protection System (MPS) was designed to turn the beam off during a fault condition in less than 20 μseconds [2] as these errant beam pulses were not unexpected. Unfortunately an improperly operating MPS was not turning off the beam within the designed 20 μseconds, and the SRF cavities were being damaged. The MPS issues were corrected, and the SRF performance was restored with cavity thermal cycling and RF processing. However, the SRF cavity performance has continued to degrade, though at a reduced rate compared to 2009. This paper will detail further study of errant beam frequency, amount lost per event, causes, and the corrective actions imposed since the initial event.