LINAC2016 - List of Authors (Fong, K.)

Paper	Title	Page
TUPRC020	The TRIUMF ARIEL RF Modulated Thermionic Electron Source	458
	F. Ames, Y.-C. Chao, K. Fong, N. Khan, S.R. Koscielniak, A. Laxdal, L. Merminga, T. Planche, S. Saminathan, D.W. Storey TRIUMF, Vancouver, Canada Y.-C. Chao, L. Merminga SLAC, Menlo Park, California, USA C.K. Sinclair Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: ARIEL is funded by the Canada Foundation for Innovation, the Provinces AB, BC, MA, ON, QC, and TRIUMF. TRIUMF receives funding via a contribution agreement with the National Research Council of Canada Within the ARIEL (Advanced Rare IsotopE Laboratory) at TRIUMF, a high power electron beam is used to produce radioactive ion beams via photo-fission. The electron beam is accelerated in a superconducting linac up to 50 MeV. The electron source provides electron bunches with charge up to 16 pC at a repetition frequency of 650 MHz leading to an average current of 10 mA . The kinetic energy of the electrons has been chosen to be 300 keV to allow direct injection into an accelerator cavity. The main components of the source are a gridded dispenser cathode (CPI 'Y845) in an SF6 filled vessel and an in-air HV power supply. The beam is bunched by applying DC and RF fields to the grid. Unique features of the gun are its cathode/anode geometry to reduce field emission, and transmission of RF modulation via a dielectric (ceramic) waveguide through the SF6. The latter obviates the need for an HV platform inside the vessel to carry the RF generator and results in a significantly smaller/simpler vessel. The source has been installed and first tests with accelerated beams have been performed. Measurements of the beam properties and results from the commissioning of the source will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC020
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TUPLR009	An Iterative Learning Feedforward Controller for the TRIUMF e-linac	485
	M.P. Laverty, K. Fong TRIUMF, Vancouver, Canada
	In the TRIUMF e-linac design, beam stability to within 0.1% within 10 μs in pulse mode is a design requirement. Traditional feedback control systems cannot respond within this time frame, so some form of feedforward control is needed. Even conventional feedforward may not be sufficient due to differences between the required feedforward signal and the actual beam-loading current. For this reason, an adaptive feedforward system using an iterative learning controller was developed for the e-linac LLRF. It can anticipate repetitive beam disturbance patterns by learning from previous iterations. The design and implementation of such a control algorithm is outlined, some simulation results are presented, and some preliminary test results with an actual cavity are illustrated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR009
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THOP06	Novel Scheme to Tune RF Cavities Using Reflected Power	757
SPWR034	use link to see paper's listing under its alternate paper code
THPLR058	use link to see paper's listing under its alternate paper code
	R. Leewe, K. Fong, Z. Shahriari TRIUMF, Vancouver, Canada M. Moallem SFU, Surrey, Canada
	Tuning of the natural resonance frequency of an RF cavity is essential for accelerator structures to achieve efficient beam acceleration and to reduce power requirements. Typically operational cavities are tuned using phase comparison techniques. The phase measurement is subject to temperature drifts and renders this technique labor and time intensive. To eliminate the phase measurement, reduce human oversight and speed up the start-up time for each cavity, this paper presents a control scheme that relies solely on the reflected power measurements. A sliding mode extremum seeking algorithm is used to minimize the reflected power. To avoid tuning motor abrasion, a variable gain minimizes motor movement around the optimum operating point. The system has been tested and is fully commissioned on two drift tube linear accelerator tanks in TRIUMF's ISAC I linear accelerator. Experimental results show that the resonance frequency can be tuned to its optimum operating point while the start-up time of a single cavity and the accompanied human oversight are significantly decreased.
	Poster THOP06 [0.244 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP06
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THPRC022	The Cryogenic Performance of the ARIEL E-Linac Cryomodules	815
	Y. Ma, K. Fong, P.R. Harmer, T. Junginger, D. Kishi, A.N. Koveshnikov, R.E. Laxdal, N. Muller, Z.Y. Yao, V. Zvyagintsev TRIUMF, Vancouver, Canada E. Thoeng UBC & TRIUMF, Vancouver, British Columbia, Canada
	The Advanced Rare Isotope Laboratory (ARIEL) project at TRIUMF requires a 50 MeV superconducting electron Linac consisting of five nine cell 1.3 GHz cavities divided into three cryomodules with one, two and two cavities in each module respectively. The cryomodule design utilizes a unique box cryomodule with a top-loading cold mass. LHe is distributed in parallel to each cryomodule at 4 K and at ~1.2 bar. Each cryomodule has a cryogenic insert on board that receives the 4 K liquid and produces 2 K liquid into a cavity phase separator. In the cryomodules the natural two-phase convection loops, i.e. siphon loop, are installed which supply 4 K liquid to thermal intercepts and return the vaporized liquid to the 4 K reservoir as a refrigerator load. The design of the cryomodule, the simulation results with Ansys Fluent and the results of the cold tests will be presented. mayanyun@triumf.ca
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC022
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Paper

Title

Page

The TRIUMF ARIEL RF Modulated Thermionic Electron Source

458

F. Ames, Y.-C. Chao, K. Fong, N. Khan, S.R. Koscielniak, A. Laxdal, L. Merminga, T. Planche, S. Saminathan, D.W. Storey
TRIUMF, Vancouver, Canada
Y.-C. Chao, L. Merminga
SLAC, Menlo Park, California, USA
C.K. Sinclair
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: ARIEL is funded by the Canada Foundation for Innovation, the Provinces AB, BC, MA, ON, QC, and TRIUMF. TRIUMF receives funding via a contribution agreement with the National Research Council of Canada
Within the ARIEL (Advanced Rare IsotopE Laboratory) at TRIUMF, a high power electron beam is used to produce radioactive ion beams via photo-fission. The electron beam is accelerated in a superconducting linac up to 50 MeV. The electron source provides electron bunches with charge up to 16 pC at a repetition frequency of 650 MHz leading to an average current of 10 mA . The kinetic energy of the electrons has been chosen to be 300 keV to allow direct injection into an accelerator cavity. The main components of the source are a gridded dispenser cathode (CPI 'Y845) in an SF6 filled vessel and an in-air HV power supply. The beam is bunched by applying DC and RF fields to the grid. Unique features of the gun are its cathode/anode geometry to reduce field emission, and transmission of RF modulation via a dielectric (ceramic) waveguide through the SF6. The latter obviates the need for an HV platform inside the vessel to carry the RF generator and results in a significantly smaller/simpler vessel. The source has been installed and first tests with accelerated beams have been performed. Measurements of the beam properties and results from the commissioning of the source will be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC020

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

TUPLR009

An Iterative Learning Feedforward Controller for the TRIUMF e-linac

485

M.P. Laverty, K. Fong
TRIUMF, Vancouver, Canada

In the TRIUMF e-linac design, beam stability to within 0.1% within 10 μs in pulse mode is a design requirement. Traditional feedback control systems cannot respond within this time frame, so some form of feedforward control is needed. Even conventional feedforward may not be sufficient due to differences between the required feedforward signal and the actual beam-loading current. For this reason, an adaptive feedforward system using an iterative learning controller was developed for the e-linac LLRF. It can anticipate repetitive beam disturbance patterns by learning from previous iterations. The design and implementation of such a control algorithm is outlined, some simulation results are presented, and some preliminary test results with an actual cavity are illustrated.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR009

Export •

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

THOP06

Novel Scheme to Tune RF Cavities Using Reflected Power

757

SPWR034

use link to see paper's listing under its alternate paper code

THPLR058

use link to see paper's listing under its alternate paper code

R. Leewe, K. Fong, Z. Shahriari
TRIUMF, Vancouver, Canada
M. Moallem
SFU, Surrey, Canada

Tuning of the natural resonance frequency of an RF cavity is essential for accelerator structures to achieve efficient beam acceleration and to reduce power requirements. Typically operational cavities are tuned using phase comparison techniques. The phase measurement is subject to temperature drifts and renders this technique labor and time intensive. To eliminate the phase measurement, reduce human oversight and speed up the start-up time for each cavity, this paper presents a control scheme that relies solely on the reflected power measurements. A sliding mode extremum seeking algorithm is used to minimize the reflected power. To avoid tuning motor abrasion, a variable gain minimizes motor movement around the optimum operating point. The system has been tested and is fully commissioned on two drift tube linear accelerator tanks in TRIUMF's ISAC I linear accelerator. Experimental results show that the resonance frequency can be tuned to its optimum operating point while the start-up time of a single cavity and the accompanied human oversight are significantly decreased.

Poster THOP06 [0.244 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP06

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THPRC022

The Cryogenic Performance of the ARIEL E-Linac Cryomodules

815

Y. Ma, K. Fong, P.R. Harmer, T. Junginger, D. Kishi, A.N. Koveshnikov, R.E. Laxdal, N. Muller, Z.Y. Yao, V. Zvyagintsev
TRIUMF, Vancouver, Canada
E. Thoeng
UBC & TRIUMF, Vancouver, British Columbia, Canada

The Advanced Rare Isotope Laboratory (ARIEL) project at TRIUMF requires a 50 MeV superconducting electron Linac consisting of five nine cell 1.3 GHz cavities divided into three cryomodules with one, two and two cavities in each module respectively. The cryomodule design utilizes a unique box cryomodule with a top-loading cold mass. LHe is distributed in parallel to each cryomodule at 4 K and at ~1.2 bar. Each cryomodule has a cryogenic insert on board that receives the 4 K liquid and produces 2 K liquid into a cavity phase separator. In the cryomodules the natural two-phase convection loops, i.e. siphon loop, are installed which supply 4 K liquid to thermal intercepts and return the vaporized liquid to the 4 K reservoir as a refrigerator load. The design of the cryomodule, the simulation results with Ansys Fluent and the results of the cold tests will be presented.
mayanyun@triumf.ca

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC022

Export •

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