CYCLOTRONS2022 - List of Authors (Fu, X.L.)

Paper	Title	Page
WEPO017	A New Design of CYCIAE230 Superconducting Cyclotron RF-Driven System	237
	Z.G. Yin, X.L. Fu, B. Ji, X. Mu, S. Pei, J.Y. Wei, T.J. Zhang CIAE, Beijing, People’s Republic of China
	A superconducting cyclotron with a beam energy of 246.2MeV has been developed and commissioned by the China Institute of Atomic Energy. The RF system of the first CYCIAE-230 cyclotron adopts two tetrode amplifiers to drive the cavities simultaneously. The driven power is 180 degrees out of phase and each of the amplifiers was designed able to deliver 75kW RF power to the cavities. In practice, it was found that the driven power is beyond necessary and only 80kW RF power is required for the beam. Hence, an upgrade of the existing RF-driven system to the stare-of-art of solid-state technology is put forward by the CIAE cyclotron team. Furthermore, this alternative design also includes an optimization of the coupling between amplifiers and the cavities, since the old coupler shows nonidealities under long-term high-power operations. A driven schema utilizing multiple low-power capacitive couplers is designed to address this issue, taking advantage of the cavity as a power combiner. In this paper, a review of the existing RF-driven system will be given first. It will be followed by an analysis of the limitation of such a system in practice. A new design of the solid amplifier, the new driven method, and a capacitive window will also be reported.
DOI •	reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-WEPO017
About •	Received ※ 25 December 2022 — Revised ※ 29 January 2023 — Accepted ※ 09 February 2023 — Issue date ※ 02 June 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPO015	TRIUMF LLRF Control System Upgrade	91
	X.L. Fu, T. Au, K. Fong, Q. Zheng TRIUMF, Vancouver, Canada
	The LLRF system for Transfer line from Drift Tube LINAC(DTL) to Superconducting Linac (SCB) (DSB) was an analog-digital hybrid system running at 35.36MHz. The system controls the amplitude/phase and tuning for a buncher cavity on the beamline. During the 2022 October shutdown, the system is upgraded to a new fully-digital LLRF system. The new digital LLRF system is based on TRIUMF’s universal LLRF hardware with a new firmware. Instead of using a VXI crate, the new system adopts a NIM bin and uses USB communication with the local control PC. The amplitude/phase regulation is implemented in the FPGA firmware, and the tuning loop is implemented in the PC software, but driven by the FPGA. The Debian 11 linux OS is running on ARM CPU, and the new digital LLRF system works as a standard window HID device. The linux OS allows the firmware be updated in-situ using Ethernet communication. The detailed design is described in this paper.
	Poster MOPO015 [6.084 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-MOPO015
About •	Received ※ 02 December 2022 — Revised ※ 11 January 2023 — Accepted ※ 01 February 2023 — Issue date ※ 19 February 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPO016	Control of Cyclotron Vertical Deflector for Proton Therapy	95
	F.D. Yang, T.Y. Jiang, X. Mu, Y. Wang, Z.G. Yin, T.J. Zhang CIAE, Beijing, People’s Republic of China X.L. Fu TRIUMF, Vancouver, Canada
	China Institute of Atomic Energy (CIAE) has designed a superconducting cyclotron CYCIAE-230 to enhance the domestic development of proton therapy. A research program on the beamline and experimental stations for the proton therapy and the space science was launched by China National Nuclear Corporation (CNNC). The modern therapy methodology often requires rapid beam modulation on both the beam energy and the intensity. In this scenario, a vertical deflector is designed and installed in the cyclotron’s central region. Applying a high-voltage electric field between the two plates can quickly adjust the intensity of the low-energy beam. Nevertheless, the voltage applied is nonlinear to the beam intensity. According to this requirement, a homemade controller for the vertical deflector is designed. Since the beam loss caused by the energy degrader is also nonlinear, this controller can compensate for the beam loss caused by energy modulation. To realize real-time control, the controller combines Field Programmable Gate Array (FPGA) and Digital Signal Process (DSP) as its control scheme design. Carried out by the DSP by interpolating the lookup table data, a feed-forward regulation is also designed to take care of the nonlinear compensation for the beam loss on the energy degrader. In the meantime, an ionized chamber provides feedback readings of the intensity just before the nozzle. A PID algorithm is also included by using FPGA, to archive the feedback control of the vertical deflector.
DOI •	reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-MOPO016
About •	Received ※ 30 December 2022 — Revised ※ 27 January 2023 — Accepted ※ 09 February 2023 — Issue date ※ 02 May 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPO017	RF Cavity Resonant Control Using Mimimal Seeking Sliding Mode Controller	99
	K. Fong, T. Au, X.L. Fu, R. Leewe, Q. Zheng TRIUMF, Vancouver, Canada
	Accelerating RF normal conducting cavities having Quality Factors of over 10³. These cavities must be constantly tuned to maintain resonance for maximum power efficiency. Traditional tuning method uses ’phase comparison method’ by monitoring the phase shift across the input and output of the cavity. This method suffers from phase drift due to diurnal temperature variations. Since 2017, TRIUMF ISAC-1 cavities are tuned using minimal seeking sliding mode controllers, which eliminate effects drift due to temperature changes. As with all extremum seeking algorithm, chattering is invariable present in the system, especially near the end-stage. This paper also includes a new chattering suppression method known as ’skipping surface’, which is slated to be installed in ISAC-1 LLRF upgrade in 2023.
	Poster MOPO017 [0.969 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-MOPO017
About •	Received ※ 26 December 2022 — Revised ※ 12 January 2023 — Accepted ※ 01 February 2023 — Issue date ※ 25 May 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPO007	Direct Sampling Digital Low-Level RF Control for CIAE BNCT Cyclotron	311
	X. Mu, J.Y. Wei, Z.G. Yin CIAE, Beijing, People’s Republic of China X.L. Fu TRIUMF, Vancouver, Canada
	Boron Neutron Capture Therapy "BNCT" can be delivered using a high current cyclotron, resulting more compact and environmentally friendly design, yet the difficulties remain in the cyclotron part, particularly in RF systems. The high beam loading challenges the stability of the amplifiers, as well as the control loops. Especially in our case, the wall loss of each cavity is more than the beam-loading power of the CIAE BNCT cyclotron. To address the heavy beam loading coefficient, a higher-performance ADRC control algorithm is evaluated, together with the regular PID control. In the meantime, a direct sampling/synthesizing digital low-level RF control hardware design is put forward to have more flexibility in control implementation. Since this new design adopts Xilinx SOC as the main controller, it is convenient to combine real-time control algorithm with high-level control through Advanced Extensible Interface. In this LLRF design, the amplitude and phase control using PID control is implemented in the PS end, and the tuning control is taking advantage of the ADRC algorithm in the PL end. Using a symmetrical design, together with the buncher control, in total, regulation of three loops are achieved using two control boards. The software/hardware design as well as the commission result will be reported in this paper.
	Poster THPO007 [2.567 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-THPO007
About •	Received ※ 29 December 2022 — Revised ※ 21 January 2023 — Accepted ※ 31 January 2023 — Issue date ※ 01 April 2023
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

A New Design of CYCIAE230 Superconducting Cyclotron RF-Driven System

237

Z.G. Yin, X.L. Fu, B. Ji, X. Mu, S. Pei, J.Y. Wei, T.J. Zhang
CIAE, Beijing, People’s Republic of China

A superconducting cyclotron with a beam energy of 246.2MeV has been developed and commissioned by the China Institute of Atomic Energy. The RF system of the first CYCIAE-230 cyclotron adopts two tetrode amplifiers to drive the cavities simultaneously. The driven power is 180 degrees out of phase and each of the amplifiers was designed able to deliver 75kW RF power to the cavities. In practice, it was found that the driven power is beyond necessary and only 80kW RF power is required for the beam. Hence, an upgrade of the existing RF-driven system to the stare-of-art of solid-state technology is put forward by the CIAE cyclotron team. Furthermore, this alternative design also includes an optimization of the coupling between amplifiers and the cavities, since the old coupler shows nonidealities under long-term high-power operations. A driven schema utilizing multiple low-power capacitive couplers is designed to address this issue, taking advantage of the cavity as a power combiner. In this paper, a review of the existing RF-driven system will be given first. It will be followed by an analysis of the limitation of such a system in practice. A new design of the solid amplifier, the new driven method, and a capacitive window will also be reported.

DOI •

reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-WEPO017

About •

Received ※ 25 December 2022 — Revised ※ 29 January 2023 — Accepted ※ 09 February 2023 — Issue date ※ 02 June 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPO015

TRIUMF LLRF Control System Upgrade

91

X.L. Fu, T. Au, K. Fong, Q. Zheng
TRIUMF, Vancouver, Canada

The LLRF system for Transfer line from Drift Tube LINAC(DTL) to Superconducting Linac (SCB) (DSB) was an analog-digital hybrid system running at 35.36MHz. The system controls the amplitude/phase and tuning for a buncher cavity on the beamline. During the 2022 October shutdown, the system is upgraded to a new fully-digital LLRF system. The new digital LLRF system is based on TRIUMF’s universal LLRF hardware with a new firmware. Instead of using a VXI crate, the new system adopts a NIM bin and uses USB communication with the local control PC. The amplitude/phase regulation is implemented in the FPGA firmware, and the tuning loop is implemented in the PC software, but driven by the FPGA. The Debian 11 linux OS is running on ARM CPU, and the new digital LLRF system works as a standard window HID device. The linux OS allows the firmware be updated in-situ using Ethernet communication. The detailed design is described in this paper.

Poster MOPO015 [6.084 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-MOPO015

About •

Received ※ 02 December 2022 — Revised ※ 11 January 2023 — Accepted ※ 01 February 2023 — Issue date ※ 19 February 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPO016

Control of Cyclotron Vertical Deflector for Proton Therapy

95

F.D. Yang, T.Y. Jiang, X. Mu, Y. Wang, Z.G. Yin, T.J. Zhang
CIAE, Beijing, People’s Republic of China
X.L. Fu
TRIUMF, Vancouver, Canada

China Institute of Atomic Energy (CIAE) has designed a superconducting cyclotron CYCIAE-230 to enhance the domestic development of proton therapy. A research program on the beamline and experimental stations for the proton therapy and the space science was launched by China National Nuclear Corporation (CNNC). The modern therapy methodology often requires rapid beam modulation on both the beam energy and the intensity. In this scenario, a vertical deflector is designed and installed in the cyclotron’s central region. Applying a high-voltage electric field between the two plates can quickly adjust the intensity of the low-energy beam. Nevertheless, the voltage applied is nonlinear to the beam intensity. According to this requirement, a homemade controller for the vertical deflector is designed. Since the beam loss caused by the energy degrader is also nonlinear, this controller can compensate for the beam loss caused by energy modulation. To realize real-time control, the controller combines Field Programmable Gate Array (FPGA) and Digital Signal Process (DSP) as its control scheme design. Carried out by the DSP by interpolating the lookup table data, a feed-forward regulation is also designed to take care of the nonlinear compensation for the beam loss on the energy degrader. In the meantime, an ionized chamber provides feedback readings of the intensity just before the nozzle. A PID algorithm is also included by using FPGA, to archive the feedback control of the vertical deflector.

DOI •

reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-MOPO016

About •

Received ※ 30 December 2022 — Revised ※ 27 January 2023 — Accepted ※ 09 February 2023 — Issue date ※ 02 May 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPO017

RF Cavity Resonant Control Using Mimimal Seeking Sliding Mode Controller

99

K. Fong, T. Au, X.L. Fu, R. Leewe, Q. Zheng
TRIUMF, Vancouver, Canada

Accelerating RF normal conducting cavities having Quality Factors of over 10³. These cavities must be constantly tuned to maintain resonance for maximum power efficiency. Traditional tuning method uses ’phase comparison method’ by monitoring the phase shift across the input and output of the cavity. This method suffers from phase drift due to diurnal temperature variations. Since 2017, TRIUMF ISAC-1 cavities are tuned using minimal seeking sliding mode controllers, which eliminate effects drift due to temperature changes. As with all extremum seeking algorithm, chattering is invariable present in the system, especially near the end-stage. This paper also includes a new chattering suppression method known as ’skipping surface’, which is slated to be installed in ISAC-1 LLRF upgrade in 2023.

Poster MOPO017 [0.969 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-MOPO017

About •

Received ※ 26 December 2022 — Revised ※ 12 January 2023 — Accepted ※ 01 February 2023 — Issue date ※ 25 May 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPO007

Direct Sampling Digital Low-Level RF Control for CIAE BNCT Cyclotron

311

X. Mu, J.Y. Wei, Z.G. Yin
CIAE, Beijing, People’s Republic of China
X.L. Fu
TRIUMF, Vancouver, Canada

Boron Neutron Capture Therapy "BNCT" can be delivered using a high current cyclotron, resulting more compact and environmentally friendly design, yet the difficulties remain in the cyclotron part, particularly in RF systems. The high beam loading challenges the stability of the amplifiers, as well as the control loops. Especially in our case, the wall loss of each cavity is more than the beam-loading power of the CIAE BNCT cyclotron. To address the heavy beam loading coefficient, a higher-performance ADRC control algorithm is evaluated, together with the regular PID control. In the meantime, a direct sampling/synthesizing digital low-level RF control hardware design is put forward to have more flexibility in control implementation. Since this new design adopts Xilinx SOC as the main controller, it is convenient to combine real-time control algorithm with high-level control through Advanced Extensible Interface. In this LLRF design, the amplitude and phase control using PID control is implemented in the PS end, and the tuning control is taking advantage of the ADRC algorithm in the PL end. Using a symmetrical design, together with the buncher control, in total, regulation of three loops are achieved using two control boards. The software/hardware design as well as the commission result will be reported in this paper.

Poster THPO007 [2.567 MB]

DOI •

reference for this paper ※ doi:10.18429/JACoW-CYCLOTRONS2022-THPO007

About •

Received ※ 29 December 2022 — Revised ※ 21 January 2023 — Accepted ※ 31 January 2023 — Issue date ※ 01 April 2023

Cite •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)