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Journal Articles

Development of LLRF control software for the J-PARC 400 MeV Linac

Fang, Z.*; Michizono, Shinichiro*; Anami, Shozo*; Yamaguchi, Seiya*; Naito, Fujio*; Fukui, Yuji*; Kobayashi, Tetsuya; Suzuki, Hiroyuki; Chishiro, Etsuji; Shinozaki, Shinichi

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.1068 - 1070, 2010/08

The output energy of the J-PARC proton Linac will be upgraded from 181 to 400 MeV in the next two years by adding 972-MHz high-beta acceleration sections. The RF signals are controlled by the FPGA-based digital feedback control systems installed in a compact PCI (cPCI). Recently, the LLRF control software has also been upgraded for the J-PARC Linac, especially for the 972-MHz high-beta systems. Many functions have been added to the LLRF control software, such as (1) gradually increasing the feedback gains in the feedback loop instead of fixed ones, (2) automatic chopped-beam compensation, (3) automatically switching the beam loading compensation in accordance with the different beam operation mode, (4) input RF-frequency tuning carried out by a FPGA to match the RF cavities during the RF start-up, (5) auto-tuning of the RF cavity tuner by detecting the phase curve of the RF cavity during the field decay instead of the phase difference between the cavity input and output signals.

Journal Articles

LLRF controller upgrade for the J-PARC 400 MeV linac

Fang, Z.*; Michizono, Shinichiro*; Anami, Shozo*; Yamaguchi, Seiya*; Naito, Fujio*; Fukui, Yuji*; Kawamura, Masato*; Kubota, Chikashi*; Nammo, Kesao*; Kobayashi, Tetsuya; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.1434 - 1436, 2010/05

The output energy of the J-PARC proton linac will be upgraded from 181 to 400 MeV in the next two years by adding high-b acceleration sections. The upgrade of the FPGA-based digital LLRF controller for the 400 MeV linac will be presented in this paper. This new LLRF controller works for both the 324-MHz low-b and 972-MHz high-b sections. Many functions have been added into the LLRF controller, such as (1) working for different RF systems, (2) gradually increasing the feedback gains in the feedback loop instead of fixed ones, (3) automatic chopped beam compensation, (4) automatically switching the beam loading compensation in accordance with different beam operation mode, (5) input RF-frequency tuning to match the RF cavities during RF start-up, and (6) auto-tuning of the RF cavity tuner by detecting the phase curve of the RF cavity during the field decay instead of the phase difference between the cavity input and output signals.

Journal Articles

Status of the J-PARC RFQ

Hasegawa, Kazuo; Morishita, Takatoshi; Kondo, Yasuhiro; Oguri, Hidetomo; Kobayashi, Tetsuya; Naito, Fujio*; Yoshioka, Masakazu*; Matsumoto, Hiroshi*; Kawamata, Hiroshi*; Hori, Yoichiro*; et al.

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.693 - 695, 2010/03

The J-PARC RFQ (length 3.1m, 4-vane type, 324 MHz) accelerates a beam from the ion source to the DTL. The beam test of the linac was started in November 2006 and 181 MeV beam was successfully accelerated in January 2007. Since then, the linac has been delivered beams for commissioning of the linac itself, downstream accelerators and facilities. Trip rates of the RFQ, however, suddenly increased in Autumn 2008, and we are suffering from this issue for user run operation. We tried to recover by tender conditioning, modification of RF control, improvement of vacuum and so on. We manage to have beam operation. In this report, we describe the status of the RFQ.

Journal Articles

Automatic frequency matching for cavity warming-up in J-PARC linac digital LLRF control

Kobayashi, Tetsuya; Anami, Shozo*; Michizono, Shinichiro*; Fang, Z.*; Suzuki, Hiroyuki; Yamaguchi, Seiya*

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1065 - 1067, 2010/03

In the J-PARC Linac LLRF, for the cavity start-up, the cavity resonance is automatically controlled to be the accelerating frequency (324 MHz and 972 MHz) with a mechanical tuner installed on the cavity. Figure 1: FPGA block diagram of the digital FB and FF control system for the J-PARC linac LLRF. We are planning to introduce a new method of the cavity-input frequency matching into the digital LLRF control system instead of the tuner control for the cavity start-up. In order to match the frequency with the detuned cavity, the output RF frequency is modulated by way of phase rotation with the I/Q modulator, while the cavity tuner is fixed. The detuning of the cavity is obtained from phase gradient of the cavity field decay at the RF-pulse end and the phase rotation is automatically controlled by a FPGA and a DSP. No hardware modification is necessary for this frequency modulation method.

Journal Articles

972-MHz RF digital feedback control system for J-PARC linac

Kobayashi, Tetsuya; Michizono, Shinichiro*; Fang, Z.*; Matsumoto, Toshihiro*; Suzuki, Hiroyuki; Yamaguchi, Seiya*; Okada, Yoshihito*

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1068 - 1070, 2010/03

A 972-MHz RF system is being developed for 400-MeV upgrade of the J-PARC linac. The accelerating field stabilities should be less than $$pm$$1% in amplitude and $$pm$$1$$^{circ}$$ in phase. The basic digital LLRF (Low-Level RF) concept is the same as that of the present 324-MHz system with a compact-PCI crate. The main alterations are RF and clock generator (RF&CLK), mixer and I/Q modulator (IQ&Mixer) and digital LLRF algorithm. Since the typical decay time of the new system is faster (because its operational frequency is higher than that of the present 324-MHz cavity), chopped beam compensation is essential. The performance study of the digital feedback system with a cavity simulator is summarized.

Journal Articles

Automatic frequency matching for cavity warming-up in J-PARC linac digital LLRF control

Kobayashi, Tetsuya; Suzuki, Hiroyuki; Anami, Shozo*; Yamaguchi, Seiya*; Michizono, Shinichiro*; Fang, Z.*

Proceedings of 2009 Particle Accelerator Conference (PAC '09) (DVD-ROM), p.2213 - 2215, 2009/05

In the J-PARC Linac LLRF, for the cavity start-up, the cavity resonance is automatically controlled to be the accelerating frequency (324 MHz and 972 MHz) with a mechanical tuner installed on the cavity. We are planning to introduce a new method of the cavity-input frequency matching into the digital LLRF control system instead of the tuner control for the cavity start-up. In order to match the frequency with the detuned cavity, the output RF frequency is modulated by way of phase rotation with the I/Q modulator, while the cavity tuner is fixed. The detuning of the cavity is obtained from phase gradient of the cavity field decay at the RF-pulse end and the phase rotation is automatically controlled by a FPGA and a DSP. No hardware modification is necessary for this frequency modulation method. The cost reduction or the high durability for the mechanical tuner production is expected in the future.

Journal Articles

Digital feedback control for 972 MHz RF system of J-PARC linac

Michizono, Shinichiro*; Fang, Z.*; Matsumoto, Toshihiro*; Yamaguchi, Seiya*; Kobayashi, Tetsuya; Okada, Yoshihito*

Proceedings of 2009 Particle Accelerator Conference (PAC '09) (DVD-ROM), p.2201 - 2203, 2009/05

Upgrade of J-PARC linac has been planed using 972 MHz rf system. The rf eld regulation is required to be less than $$pm$$ 1% in amplitude and $$pm$$ 1$$^{circ}$$. in phase. The basic digital llrf concept is same as the present 324 MHz llrf system using a compact PCI crate. The main alterations are rf and clock generator (RF&LK), mixer and IQ modulator (IQ&Mixer) and digital llrf algorithm. Since the typical decay time is faster (due to higher operational frequency than present 324 MHz cavity), chopped beam compensation is one of the main concerns. Performance of the digital feedback system using a cavity simulator is summarized.

Journal Articles

Operating experience of the J-PARC linac

Hasegawa, Kazuo; Asano, Hiroyuki; Chishiro, Etsuji; Hori, Toshihiko; Ito, Takashi; Kobayashi, Tetsuya; Kondo, Yasuhiro; Namekawa, Yuya; Oguri, Hidetomo; Okoshi, Kiyonori; et al.

Proceedings of 24th International Linear Accelerator Conference (LINAC 2008) (CD-ROM), p.55 - 57, 2009/00

The beam commissioning of the J-PARC linac started in November 2006 and 181 MeV acceleration was successfully achieved in January 2007. The linac has delivered beams to the 3 GeV Rapid Cycling Synchrotron for its commissioning, and then, the subsequent Main Ring Synchrotron and the neutron target commissioning. The linac uses a Cs-free LaB$$_{6}$$-driven ion source and 20 units of 324 MHz klystrons. As of June 2008, the operation times are about 3,000 and 6,000 hours for the ion source and the RF source, respectively. The operating experience of the linac is described.

Journal Articles

Pulse-by-pulse switching of beam loading compensation in J-PARC linac RF control

Kobayashi, Tetsuya; Chishiro, Etsuji; Suzuki, Hiroyuki; Anami, Shozo*; Fang, Z.*; Michizono, Shinichiro*; Yamaguchi, Seiya*

Proceedings of 24th International Linear Accelerator Conference (LINAC 2008) (CD-ROM), p.1054 - 1056, 2009/00

For the J-PARC linac low level RF system, a new function that switches the feed-forward control parameters in every pulse was installed into the digital accelerating-field control system, in order to compensate beam-loading change by pulses in the operation of 25-Hz repetition. The linac provides a 50-mA peak current proton beam to a 3-GeV rapid-cycling synchrotron (RCS). Then the RCS distributes the 3-GeV beam into a following 50-GeV synchrotron (main ring, MR) and the Materials and Life Science Facility (MLF), which is one of the experimental facilities in the J-PARC. The 500-us long macro pulses from the ion source of the linac should be chopped into medium pulses for injection into the RCS. The duty (width or repetition) of the medium pulse depends on which facility the RCS provides the beam to the MR or MLF. Therefore the beam loading compensation needs to be corrected for the change of the medium pulse duty in the 25-Hz operation.

Journal Articles

LLRF control system of the J-PARC linac

Fang, Z.*; Anami, Shozo*; Michizono, Shinichiro*; Yamaguchi, Seiya*; Kobayashi, Tetsuya; Suzuki, Hiroyuki

Proceedings of 24th International Linear Accelerator Conference (LINAC 2008) (CD-ROM), p.1039 - 1041, 2009/00

In the J-PARC proton linac, each klystron drives two RF cavities. The RF amplitude and phase of the cavities are controlled by an FPGA-based digital feedback control system. The test results show that the variations in the cavity amplitude and phase are less than $$pm$$ 0.1% and $$pm$$ 0.1 $$^{circ}$$ without beam loading, or $$pm$$ 0.3% and $$pm$$ 0.2 $$^{circ}$$ with beam loading. The tuning of each cavity is also controlled by a DSP of this control system. The cavity auto-tuning is successfully controlled to keep the detuned phase within $$pm$$ 1 degree. In our RF system, the tuning information including detuned frequency and phase, and Q-value of each cavity are measured in real-time and displayed in the PLC touch panel of the control system.

Journal Articles

Development of digital low level rf system

Michizono, Shinichiro*; Anami, Shozo*; Katagiri, Hiroaki*; Fang, Z.*; Matsumoto, Toshihiro*; Miura, Takako*; Yano, Yoshiharu*; Yamaguchi, Seiya*; Kobayashi, Tetsuya

Kasokuki, 5(2), p.127 - 136, 2008/07

One of the biggest advantages of the digital low level rf (LLRF) system is its flexibility. Owing to the recent rapid progress in digital devices (such as ADCs and DACs) and telecommunication devices (mixers and IQ modulators), digital LLRF system for accelerators becomes popular in these 10 years. The J-PARC linac LLRF system adopted cPCI crates and FPGA based digital feedback system. After the successful operation of J-PARC linac LLRF system, we developed the STF (ILC test facility in KEK) LLRF system. The future R&D projects (ILC and ERL) are also described from the viewpoints of LLRF.

Journal Articles

High power test of 972 MHz waveguide systems for J-PARC Linac

Hori, Toshihiko; Yamazaki, Masayoshi; Yamaguchi, Seiya*; Hasegawa, Kazuo; Linac RF Group

NIFS-MEMO-55, p.289 - 292, 2008/03

no abstracts in English

Journal Articles

RF reference distribution system for J-PARC linac

Kobayashi, Tetsuya; Chishiro, Etsuji; Anami, Shozo*; Yamaguchi, Seiya*; Michizono, Shinichiro*

Nuclear Instruments and Methods in Physics Research A, 585(1-2), p.12 - 19, 2008/01

 Times Cited Count:2 Percentile:23.34(Instruments & Instrumentation)

For the J-PARC linac, the error in the accelerating field needs to be maintained within $$pm$$ 1% in amplitude and $$pm$$ 1$$^{circ}$$ in phase. Thus, high phase stability is required for the RF reference distribution system. A highly stable and unique RF reference distribution system was developed and installed for the J-PARC linac. A RF reference signal is converted into an optical signal and amplified by an optical amplifier. Then it is distributed through optical fiber links to 60 low-level RF control systems comprising klystron driving systems. Phase stabilized optical fiber (PSOF) is employed in the optical transfer line. The phase stability of the distributed signal was evaluated, and a phase stability of the $$pm$$ 0.2$$^{circ}$$ was obtained; consequently the required system stability was achieved. The beam acceleration to a design energy of 181 MeV for the first phase was successfully performed in February 2007. Now the beam commissioning has been steadily continued.

Journal Articles

Present status of RF source operation at J-PARC linac

Yamazaki, Masayoshi; Chishiro, Etsuji; Kobayashi, Tetsuya; Hori, Toshihiko; Suzuki, Hiroyuki; Anami, Shozo*; Kawamura, Masato*; Fukui, Yuji*; Nammo, Kesao*; Fang, Z.*; et al.

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.485 - 487, 2008/00

no abstracts in English

Journal Articles

Pulse-by-pulse switching of beam loading compensation in J-PARC linac LLRF

Kobayashi, Tetsuya; Anami, Shozo*; Michizono, Shinichiro*; Fang, Z.*; Suzuki, Hiroyuki; Yamaguchi, Seiya*; Chishiro, Etsuji

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.488 - 490, 2008/00

For the J-PARC linac low level RF system, in order to compensate beam-loading change by pulses in the operation of 25-Hz repetition, a function that switches the feed-forward control parameters in every pulse were installed into the digital accelerating-field control system. The linac provides a 50-mA peak current proton beam to a 3-GeV rapid-cycling synchrotron (RCS). Then the RCS distributes the 3-GeV beam into a following 50-GeV synchrotron (main ring, MR) and the Materials and Life Science Facility (MLF), which is one of the experimental facilities in the J-PARC. The 500-us long macro pulses from the ion source of the linac should be chopped into medium pulses for injection into the RCS. The duty (width or repetition) of the medium pulse depends on which facility the RCS provides the beam to the MR or MLF. Therefore the beam loading compensation needs to be corrected for the change of the medium pulse duty in the 25-Hz operation.

Journal Articles

Auto-tuning and Q-value monitoring of RF cavities at the J-PARC linac

Fang, Z.*; Anami, Shozo*; Michizono, Shinichiro*; Yamaguchi, Seiya*; Kobayashi, Tetsuya; Suzuki, Hiroyuki

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.476 - 478, 2008/00

In the J-PARC proton linac, each klystron drives two RF cavities. The RF amplitude and phase of the cavities are controlled by an FPGA-based digital feedback control system. The tuning of each cavity is also controlled by a DSP of this control system. In this paper, three methods of f$$_{0}$$ setting of RF cavity will be discussed. The tuning method of RF cavity with flat cavity-phase decay is adopted in the actual operation of the J-PARC linac. In our RF system, the tuning information including detuned frequency and phase, and Q-value of each cavity are measured in real-time and displayed in the PLC Touch Panel of the control system.

Journal Articles

DATA collection using memory area of PLC touch panel for J-PARC linac RF

Suzuki, Hiroyuki; Chishiro, Etsuji; Kobayashi, Tetsuya; Hori, Toshihiko; Yamazaki, Masayoshi; Anami, Shozo*; Yamaguchi, Seiya*; Kawamura, Masato*; Fukui, Yuji*; Fang, Z.*

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.467 - 469, 2008/00

no abstracts in English

Journal Articles

Present status of the 972 MHz RF test stand for J-PARC 2008

Hori, Toshihiko; Yamazaki, Masayoshi; Chishiro, Etsuji; Suzuki, Hiroyuki; Ao, Hiroyuki; Hirano, Koichiro; Hasegawa, Kazuo; Yamaguchi, Seiya*

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.482 - 484, 2008/00

no abstracts in English

Journal Articles

Performance of J-PARC linac RF system

Kobayashi, Tetsuya; Chishiro, Etsuji; Hori, Toshihiko; Suzuki, Hiroyuki; Yamazaki, Masayoshi; Anami, Shozo*; Fang, Z.*; Fukui, Yuji*; Kawamura, Masato*; Michizono, Shinichiro*; et al.

Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.2128 - 2130, 2007/08

High power operation of all the RF systems of J-PARC linac was started for the cavity conditioning in October 2006. Twenty 324-MHz klystrons have supplied the power to the accelerating cavities successfully, and the beam commissioning was started in November 2006. The RF drive and control systems are working well, and required stability is satisfied.

Journal Articles

RF feedback control systems of the J-PARC linac

Fang, Z.*; Anami, Shozo*; Michizono, Shinichiro*; Yamaguchi, Seiya*; Kobayashi, Tetsuya; Suzuki, Hiroyuki

Proceedings of 2007 Particle Accelerator Conference (PAC '07) (Internet), p.2101 - 2103, 2007/08

The commissioning of the J-PARC 181-MeV proton linac was started from October of 2006. The RF sources of the linac consist of 4 solid-state amplifiers and 20 klystrons. In each RF source, the RF fields are controlled by a digital RF feedback (FB) system installed in a compact PCI (cPCI) to realize the accelerating field stability of $$pm$$1% in amplitude and $$pm$$1 degree in phase. In this paper the performance of the RF feedback control systems will be reported in detail.

54 (Records 1-20 displayed on this page)