Operational results of the Spallation Neutron Source (SNS) polyphase converter-modulator for the 140 kV klystron RF system

Reass, W.A.; Doss, J.D.; Gribble, R.F.; Lynch, M.; Rees, D.; Tallerico, P.J.; Borovina, D.L.

doi:10.1109/pac.2001.986565

“…This voltage is filtered with capacitor C1 and C2 which store sufficient charge to produce 1.3 ms pulses without excessive droop. The DC voltage is supplied to three IGBT based H-bridge circuits operating at a nominal switching frequency of 20 kHz (Reass et al, 2001). The three phases are switched with a 120 • phase shift between the phases, and the high power pulses are stepped up to high voltage using pulse transformers.…”

Section: Methodsmentioning

confidence: 99%

Application of Convolutional and Feedforward Neural Networks for Fault Detection in Particle Accelerator Power Systems

Radaideh

¹

,

Pappas

²

,

Ramuhalli

³

et al. 2022

View full text Add to dashboard Cite

High voltage converter modulators (HVCM) provide power to the accelerating cavities of the Spallation Neutron Source (SNS) facility. HVCMs experience catastrophic failures, which increase the downtime of the SNS and reduce beam time. The faults may occur due to different reasons including failures of the resonant capacitor, core saturation due to the magnetic flux, insulated-gate bipolar transistor (IGBT) failures, and others. We recently have setup a HVCM test stand to develop and test machine learning models for anomaly detection and fault prognostics. In this work, we propose binary classifiers and autoencoder architectures based on convolutional (CNN) and feedforward neural networks (FNN) to facilitate distinguishing normal from faulty waveforms coming from the HVCM during operation. The results indicate that the CNN binary classifier is the best model among the four showing very stable performance in the training and testing sets with impressive precision and recall metrics, reaching up to 99% with a very small uncertainty. The FNN classifier shows the least performance with a large uncertainty in its metrics. The performances of the two autoencoders based on CNN and FNN were in between, showing very good performance nonetheless.

show abstract

“…[1] The power supplies used with the 550 kW klystrons are capable of up to 80 kV and up to 140 A (non simultaneously) with a pulse width of up to 1.3 msec.…”

Section: Converter/modulator Power Suppliesmentioning

confidence: 99%

The RF system design for the Spallation Neutron Source

Rees

¹

,

Tallerico

²

,

Reass

³

Third IEEE International Vacuum Electronics Conference (IEEE Cat. No.02EX524)

View full text Add to dashboard Cite

Spallation Neutron Source (SNS) accelerator includes a nominally 1000 MeV, 2 mA average current linac consisting of a radio frequency quadrapole (RFQ), drift tube linac (DTL), coupled cavity linac (CCL), a medium and high beta super conducting (SC) linac, and two buncher cavities for beam transport to the ring. Los Alamos is responsible for the RF systems for all sections of the linac. The SNS linac is a pulsed proton linac and the RF system must support a 1 msec beam pulse at up to a 60 Hz repetition rate. The RFQ and DTL utilize seven, 2.5 MW klystrons and operate at 402.5 MHz. The CCL, SC, and buncher cavities operate at 805 MHz. Six, 5 MW klystrons are utilized for the CCL and buncher cavities while eighty-one 550 kW klystrons are used for the SC cavities. All of the RF hardware for the SNS linac is currently in production. This paper will present details of the RF system-level design as well as specific details of the SNS RF equipment. The design parameters will be discussed. One of the design challenges has been achieving a reasonable cost with the very large number of high-power klystrons. The approaches we used to reduce cost and the resulting design compromises will be discussed. RF SYSTEM DESIGNThe partitioning of the RF system for the SNS accelerator is illustrated in Fig. 1. The RFQ and DTLs are driven by pulsed 2.5 MW, 402.5 MHz klystrons. These accelerating structures are followed by four CCL cavities. A single, pulsed, 5 MW, 805 MHz klystron provides power to each CCL cavity. The power from the klystron is split, and the cavity is driven through two RF windows. The CCL cavities are followed by eighty-one super-conducting (SC) cavities. Each SC cavity is driven by a pulsed 550 kW klystron. The klystrons are sized to allow at least 25% power overhead in the room temperature portion, and as much as 40% in the high beta SC linac for fast cavity field control and transmission and reflection loss. Two variations of a similar power supply design are used for the linac RF systems. The RFQ, DTL, and CCL klystrons utilize a 140 kV, 90 A pulsed power supply capable of supplying an average power of 1 MW and a peak power of 11 MW. The SC linac uses an 80 kV, 140 A pulsed power supply capable of 1 MW of average power and 11 MW of peak power. Because the RF station requirements are well below the klystron rating for the RFQ and first two DTL cavities, one power supply is used to run these three systems. For the remainder of the DTL RF stations, two 2.5 MW klystrons share a single power supply. For the CCL RF stations, one 140 kV power supply is required for each klystron. The first forty-eight 550 kW klystrons are run at less than maximum power and are fed in groups of twelve from four power supplies. The next thirty-three 550 kW klystrons are run at close to maximum power are fed in groups of 11 from three power supplies due to the 11 MW peak power.The SNS klystrons do not have a modulating anode. The klystron gun is a diode gun and the pulsed power supply voltage pulses the klystron beam current and de...

show abstract

“…The power supplies used with the 2.5 and 5 MW klystrons are capable of producing up to 140 kV and up to 90 A (non simultaneously) with a pulse width of up to 1.2 msec. [1] The power supplies used with the 550 kW klystrons are capable of up to 80 kV and up to 140 A (non simultaneously) with a pulse width of up to 1.3 msec.…”

Section: Converter/modulator Power Suppliesmentioning

confidence: 99%

The RF system design for the Spallation Neutron Source

Rees

¹

,

Lynch

²

,

Tallerico

³

et al.

PACS2001. Proceedings of the 2001 Particle Accelerator Conference (Cat. No.01CH37268)

View full text Add to dashboard Cite

Spallation Neutron Source (SNS) accelerator includes a nominally 1000 MeV, 2 mA average current linac consisting of a radio frequency quadrapole (RFQ), drift tube linac (DTL), coupled cavity linac (CCL), a medium and high beta super conducting (SC) linac, and two buncher cavities for beam transport to the ring. Los Alamos is responsible for the RF systems for all sections of the linac. The SNS linac is a pulsed proton linac and the RF system must support a 1 msec beam pulse at up to a 60 Hz repetition rate. The RFQ and DTL utilize seven, 2.5 MW klystrons and operate at 402.5 MHz. The CCL, SC, and buncher cavities operate at 805 MHz. Six, 5 MW klystrons are utilized for the CCL and buncher cavities while eighty-one 550 kW klystrons are used for the SC cavities. All of the RF hardware for the SNS linac is currently in production. This paper will present details of the RF system-level design as well as specific details of the SNS RF equipment. The design parameters will be discussed. One of the design challenges has been achieving a reasonable cost with the very large number of high-power klystrons. The approaches we used to reduce cost and the resulting design compromises will be discussed. RF SYSTEM DESIGNThe partitioning of the RF system for the SNS accelerator is illustrated in Fig. 1. The RFQ and DTLs are driven by pulsed 2.5 MW, 402.5 MHz klystrons. These accelerating structures are followed by four CCL cavities. A single, pulsed, 5 MW, 805 MHz klystron provides power to each CCL cavity. The power from the klystron is split, and the cavity is driven through two RF windows. The CCL cavities are followed by eighty-one super-conducting (SC) cavities. Each SC cavity is driven by a pulsed 550 kW klystron. The klystrons are sized to allow at least 25% power overhead in the room temperature portion, and as much as 40% in the high beta SC linac for fast cavity field control and transmission and reflection loss. Two variations of a similar power supply design are used for the linac RF systems. The RFQ, DTL, and CCL klystrons utilize a 140 kV, 90 A pulsed power supply capable of supplying an average power of 1 MW and a peak power of 11 MW. The SC linac uses an 80 kV, 140 A pulsed power supply capable of 1 MW of average power and 11 MW of peak power. Because the RF station requirements are well below the klystron rating for the RFQ and first two DTL cavities, one power supply is used to run these three systems. For the remainder of the DTL RF stations, two 2.5 MW klystrons share a single power supply. For the CCL RF stations, one 140 kV power supply is required for each klystron. The first forty-eight 550 kW klystrons are run at less than maximum power and are fed in groups of twelve from four power supplies. The next thirty-three 550 kW klystrons are run at close to maximum power are fed in groups of 11 from three power supplies due to the 11 MW peak power.The SNS klystrons do not have a modulating anode. The klystron gun is a diode gun and the pulsed power supply voltage pulses the klystron beam current and de...

show abstract

Operational results of the Spallation Neutron Source (SNS) polyphase converter-modulator for the 140 kV klystron RF system

Cited by 5 publications

References 0 publications

Application of Convolutional and Feedforward Neural Networks for Fault Detection in Particle Accelerator Power Systems

Application of Convolutional and Feedforward Neural Networks for Fault Detection in Particle Accelerator Power Systems

The RF system design for the Spallation Neutron Source

The RF system design for the Spallation Neutron Source

Contact Info

Product

Resources

About