LINAC2014 - Table of Session: TUPOL (Poster Oral Presentations)

Paper

Title

Page

TUPOL01

The First Beam Recirculation and Beam Tuning in the Compact ERL at KEK

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S. Sakanaka, M. Adachi, S. Adachi, M. Akemoto, D.A. Arakawa, S. Asaoka, K. Enami, K. Endo, S. Fukuda, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, K. Hozumi, A. Ishii, X. Jin, E. Kako, Y. Kamiya, H. Katagiri, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondou, O.A. Konstantinova, T. Kume, T. Matsumoto, H. Matsumura, H. Matsushita, S. Michizono, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, N. Nakamura, K. Nakanishi, K. Nakao, K.N. Nigorikawa, T. Nogami, S. Noguchi, S. Nozawa, T. Obina, T. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sasaki, K. Satoh, M. Satoh, T. Shidara, M. Shimada, K. Shinoe, T. Shioya, T. Shishido, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, T. Takenaka, Y. Tanimoto, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
R. Hajima, S. Matsuba, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma
JAEA, Ibaraki-ken, Japan
J.G. Hwang
KNU, Deagu, Republic of Korea
M. Kuriki, Y. Seimiya
HU/AdSM, Higashi-Hiroshima, Japan
A. Valloni
CERN, Geneva, Switzerland

Superconducting(SC)-linac-based light sources, which can produce ultra-brilliant photon beams in CW operation, are attracting worldwide attention. In KEK, we have been conducting R&D efforts towards the energy-recovery-linac(ERL)-based light source* since 2006. To demonstrate the key technologies for the ERL, we constructed the Compact ERL (cERL)** from 2009 to 2013. In the cERL, high-brightness CW electron beams are produced using a 500-kV photocathode DC gun. The beams are accelerated using SC cavities, transported through a recirculation loop, decelerated in the SC cavities, and dumped. In the February of 2014, we succeeded in accelerating and recirculating the CW beams of 4.5 micro-amperes in the cERL; the beams were successfully transported from the gun to the beam dump under energy recovery operation in the main linac. Then, precise tuning of beam optics and diagnostics of beam properties are under way. We report our experience on the beam commissioning, as well as the results of initial measurements of beam properties.
* N. Nakamura, IPAC2012, TUXB02.
** S. Sakanaka et al., IPAC2013, WEPWA015.

TUPOL02

4 K Alignment of Superconducting Quarter-Wave Cavities and 9 T Solenoids in the ATLAS Intensity Upgrade Cryomodule

TUPP003

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S.H. Kim, Z.A. Conway, W.G. Jansma, M. Kedzie, M.P. Kelly, P.N. Ostroumov
ANL, Argonne, Illinois, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357.
The superconducting cavities and, especially, the magnets in high intensity ion linacs need to be aligned to the beam with typical transverse tolerances of 0.25 mm and 0.1 degrees at temperatures of 1.8 – 4.5 K. This is necessary to limit the emittance growth and minimize the beam losses. A new cryomodule with 7 superconducting quarter-wave resonators and 4 superconducting solenoids has been installed and is now operated at the Argonne Tandem Linear Accelerator System (ATLAS). We developed the techniques necessary to assemble the superconducting components in this cryomodule at room temperature so that they are aligned to the beam axis at 4.5 K. We achieved transverse alignment tolerances of <0.2 mm RMS. In this paper, we will present the details of the alignment hardware, procedures and results.

Slides TUPOL02 [0.834 MB]

TUPOL03

Completion of Efficiency and Intensity Upgrade of the ATLAS Facility

TUPP005

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P.N. Ostroumov, Z.A. Conway, C. Dickerson, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.H. Kim, Y. Luo, S.W.T. MacDonald, R.C. Murphy, B. Mustapha, R.C. Pardo, T. Reid, S.I. Sharamentov, K.W. Shepard, J.R. Specht, G.P. Zinkann
ANL, Argonne, USA
A. Perry
Illinois Institute of Technology, Chicago, Illlinois, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
The ANL Physics Division has completed a major upgrade of the ATLAS National User Facility by successfully installing a new RFQ and cryomodule. The new normal conducting CW RFQ capable of providing 295 keV/u beams of any ion with m/q ≤7 from protons to uranium was fully integrated into ATLAS and has been in routine operation for more than a year. The RFQ doubled the efficiency of beam delivery to targets and opened the possibility to accelerate much higher intensity beams. Recently, the new cryomodule containing 7 high-performance 72.75 MHz superconducting quarter-wave resonators and 4 superconducting solenoids was successfully commissioned with beam. New design and fabrication techniques for these resonators resulted in record high voltages which were achieved during the beam commissioning. The new cryomodule provides 17.5 MV accelerating voltage which will be gradually raised by increasing the input RF power and improving LLRF system. The new cryomodule, which replaced 3 old cryomodules that used split-ring cavities, is also essential for high intensity stable beams. Results of beam commissioning and operation of ATLAS with the new RFQ and cryomodule will be presented.

TUPOL04

Beam Physics Challenge in FRIB Driver Linac

TUPP045

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Y. Yamazaki, N.K. Bultman, A. Facco, Z.Q. He, M. Ikegami, M.J. Johnson, S.M. Lidia, F. Marti, G. Pozdeyev, K. Saito, J. Wei, X. Wu, Y. Zhang, Q. Zhao
FRIB, East Lansing, Michigan, USA

Funding: *Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The Facility for Rare Isotope Beams driver linac provides CW beams of all the stable ions (from protons to uranium) with a beam power of 400 kW and a minimum beam energy of 200 MeV/u in order to produce a wide variety of rare isotopes, mainly for nuclear physics study. The low beam emittances, both transverse and longitudinal, are key performance requirements, together with beam stability. These are required for efficiently separating one isotope from another, the reason for choosing this linac configuration. Multi-charge states (five charge states for the uranium case) are accelerated for maximizing the beam current, while keeping the low emittances. The efficient acceleration of high beam currents from 0.5 MeV/u through the superconducting linac is, needless to say, one of the biggest challenges. The beam power is more than 200 times higher than existing similar SC heavy ion linac. In particular, the SC cavities are difficult to protect from heavy ion beam damage, which can be 30 times larger locally than a proton beam with the same beam power. Other challenges peculiar to the FRIB linac will be presented, together with the solutions.

TUPOL05

Study of the ACS Cavity Without a Bridge Cavity

TUPP073

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F. Naito, K. Takata
KEK, Ibaraki, Japan
H. Ao, K. Hasegawa, K. Hirano, T. Morishita, N. Ouchi
JAEA/J-PARC, Tokai-mura, Japan

J-PARC has installed the Annular-ring Coupled Structure (ACS) linac to increase the beam energy up to 400 MeV. One ACS module is composed of two accelerating tanks which are coupled by the bridge cavity. The bridge cavity simplifies the handling of the multi-tank system. While it is possible to feed the RF power into the each tanks directly with the power divider and the phase shifter instead of the bridge cavity. The rf properties of the ACS linac with the direct rf-power supply system has been measured by using the low power model made of aluminum. The measured results are described in the paper.

Slides TUPOL05 [5.042 MB]

TUPOL06

Spatially Periodic RF Quadrupole LINAC

TUPP090

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SUPG013

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A.S. Plastun, A. Kolomiets
ITEP, Moscow, Russia

Spatially-periodic RF quadrupole structure is proposed as second section of front end of ion linac. It consists of conventional drift tubes and RF quadrupoles. Quadrupoles are 4-vane segments with nonzero electric potential on the longitudinal axis. Thus the accelerating electric field is formed between drift tubes and RF quadrupoles. Moreover accelerating field can be provided even inside the RF quadrupoles. It allows building structures with different focusing lattices and provides high energy gain rate.

TUPOL07

Operation Of The Versatile Accelerator Driving the Low Power ADS GUINEVERE at SCK•CEN

TUPP100

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M.A. Baylac, A. Billebaud, P. Boge, D. Bondoux, J. Bouvier, S. Chabod, G. Dargaud, E. Froidefond, E. Labussière, R. Micoud, S. Rey
LPSC, Grenoble Cedex, France
A. Kochetkov, J. Mertens, F. Van Gestel, C. Van Grieken, B. Van Houdt, G. Vittiglio
SCK•CEN, Mol, Belgium
F.R. Lecolley, J.L. Lecouey, G. Lehaut, N. Marie-Nourry
CNRS/IN2P3/LPC CAEN, Caen, France

GUINEVERE provides a low power accelerator driven system (ADS) to investigate on-line reactivity monitoring and operational procedures of an ADS. It consists of a versatile neutron source, GENEPI-3C, driving the fast sub-critical core, VENUS-F, in SCK•CEN (Belgium). GENEPI-3C is an electrostatic accelerator generating 14 MeV neutrons by bombarding a 250 keV deuteron beam onto a tritium target located within the reactor core. This accelerator produces alternatively continuous beam (up to 1 mA DC), possibly chopped with fast and adjustable interruptions, or short and intense deuteron bunches (~25 mA peak, 1 μs). This paper presents the facility and assesses the 2 years of coupled operation of the accelerator to the reactor.

Slides TUPOL07 [0.969 MB]

TUPOL08

Effect of Beam-Loading on the Breakdown Rate of High Gradient Accelerating Structures

TUPP033

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J.L. Navarro Quirante, R. Corsini, A. Degiovanni, S. Döbert, A. Grudiev, O. Kononenko, G. McMonagle, S.F. Rey, A. Solodko, I. Syratchev, F. Tecker, L. Timeo, B.J. Woolley, X.W. Wu, W. Wuensch
CERN, Geneva, Switzerland
O. Kononenko
SLAC, Menlo Park, California, USA
A. Solodko
JINR, Dubna, Moscow Region, Russia
J. Tagg
National Instruments Switzerland, Ennetbaden, Switzerland
B.J. Woolley
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
X.W. Wu
TUB, Beijing, People's Republic of China

The Compact Linear Collider (CLIC) is a study for a future room temperature electron-positron collider with a maximum center-of-mass energy of 3 TeV. To efficiently achieve such high energy, the project relies on a novel two beam acceleration concept and on high-gradient accelerating structures working at 100 MV/m. In order to meet the luminosity requirements, the break-down rate in these high-field structures has to be kept below 10 per billion. Such gradients and breakdown rates have been demonstrated by high-power RF testing several 12 GHz structures. However, the presence of beam-loading modifies the field distribution for the structure, such that a higher input power is needed in order to achieve the same accelerating gradient as the unloaded case. The potential impact on the break-down rate was never measured before. In this paper we present an experiment located at the CLIC Test Facility CTF3 recently proposed in order to quantify this effect, layout and hardware status, and discuss its first results.

Slides TUPOL08 [1.970 MB]

TUPOL09

Tuning and Field Stabilization of the CERN Linac4 Drift Tube Linac

TUPP089

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SUPG018

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M.R. Khalvati
IPM, Tehran, Iran
S. Ramberger
CERN, Geneva, Switzerland

The Drift Tube Linac (DTL) for the new linear accelerator Linac4 at CERN will accelerate H–beams of up to 40 mA average pulse current from 3 to 50 MeV. The structure consists of three cavities. The first cavity (Tank1) is a 3.9 m long tank containing 38 drift tubes, 10 fixed tuners, 2 movable tuners and 12 post-couplers, operating at a frequency of 352.2 MHz and an average accelerating field of 3.1 MV/m. This paper reports on the results and procedures used for the low–power tuning, stabilization and power coupler tuning carried out on the first Linac4 DTL tank. The upgrade of the bead pull measurement system and twists to the well-known tilt sensitivity technique are discussed.

TUPOL10

Design of Novel RF Sources to Reduce the Beam Pace-Charge Effects

TUPP123

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M. Dal Forno, A. Jensen, R.D. Ruth, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: DOE
Traditional RF sources, such as Klystrons, TWT require a magnet (such as a solenoid) in order to maintain the electron beam focusing, compensating the particle repulsion caused by space charge effects. We designed a novel RF source with an alternative approach that reduces beam space charge problems. This paper shows the design of the device, with a new formulation of the Child’s Law, and the mode-beam stability analysis. The electron beam interaction with the cavity fields has been analyzed by means of particle tracking software in order to evaluate the beam bunching and the beam dynamics.

TUPOL011

RF Input Power Couplers for High Current SRF Applications

TUPP065

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V.F. Khan, W. Anders, A. Burrill, J. Knobloch, O. Kugeler, A. Neumann
HZB, Berlin, Germany
H. Wang
JLab, Newport News, Virginia, USA

High current SRF technology is being explored in present day accelerator science. The BERLinPro project is presently being built at the HZB to address the challenges involved in high current SRF machines. A 100 mA electron beam is designed to be accelerated to 50 MeV in continuous wave (cw) mode at 1.3 GHz. One of the main challenges in this project is that of handling high input RF power for the gun as well as booster cavities where there is no energy recovery process. A high power co-axial input coupler is being developed to be used for the booster and gun cavities at the nominal beam current. The coupler is based on the KEK–cERL coupler design. The KEK coupler design has been modified to minimise the penetration of the tip in the beampipe without compromising on beam-power coupling ( Qext ~1 x 105). Herein we report on the RF design for the high power (130 kW) BERLinPro (BP) couplers along with the test stand for conditioning the couplers. We will also report on the RF conditioning of the TTF-III couplers modified for cw operation (low power ~ 10 kW) which will be utilised in a new 4-mA SRF Photoinjector and the BERLinPro main linac cryomodule.

Slides TUPOL011 [2.465 MB]

TUPOL012

Space Charge Compensation in the Linac4 LEBT for Three Injected Gas Types

TUPP036

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SUPG028

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C.A. Valerio, R. Scrivens
CERN, Geneva, Switzerland
N. Chauvin
CEA/IRFU, Gif-sur-Yvette, France

The space charge of unbunched, high intensity beams can be compensated by the trapping of charged particles in the potential well of the beam. The source of these secondary charge particles can be the residual gas in the beam line. The effect is important in the Low energy beam transport (LEBT) regions. At CERN’s Linac4, the LEBT transports a pulsed 45keV H⁻ beam, which is compensated by the positive ions, created by collision of the beam with the neutral gas in the beam pipe. The rise time and amount of compensation may be varied by the density of neutral gas and the type of gas used (through the cross-section for ion production and the mass of the resulting ion). In this paper we present measurement results for the transport of the beam at the Linac4 LEBT with the addition of hydrogen, nitrogen and krypton gases into the line, and compare them with simulations of the beam dynamics including the effect of compensating positive ions . The H⁻ beam is provided by a cesiated 2MHz RF ion source with an external solenoidal antenna, operating with 600us pulses at 0.8Hz repetition rate.

Slides TUPOL012 [4.084 MB]

Paper	Title	Page
TUPOL01	The First Beam Recirculation and Beam Tuning in the Compact ERL at KEK
TUPP075	use link to access more material from this paper's primary paper code
	S. Sakanaka, M. Adachi, S. Adachi, M. Akemoto, D.A. Arakawa, S. Asaoka, K. Enami, K. Endo, S. Fukuda, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, K. Hozumi, A. Ishii, X. Jin, E. Kako, Y. Kamiya, H. Katagiri, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondou, O.A. Konstantinova, T. Kume, T. Matsumoto, H. Matsumura, H. Matsushita, S. Michizono, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, N. Nakamura, K. Nakanishi, K. Nakao, K.N. Nigorikawa, T. Nogami, S. Noguchi, S. Nozawa, T. Obina, T. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sasaki, K. Satoh, M. Satoh, T. Shidara, M. Shimada, K. Shinoe, T. Shioya, T. Shishido, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, T. Takenaka, Y. Tanimoto, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, K. Watanabe, M. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida KEK, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan R. Hajima, S. Matsuba, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma JAEA, Ibaraki-ken, Japan J.G. Hwang KNU, Deagu, Republic of Korea M. Kuriki, Y. Seimiya HU/AdSM, Higashi-Hiroshima, Japan A. Valloni CERN, Geneva, Switzerland
	Superconducting(SC)-linac-based light sources, which can produce ultra-brilliant photon beams in CW operation, are attracting worldwide attention. In KEK, we have been conducting R&D efforts towards the energy-recovery-linac(ERL)-based light source* since 2006. To demonstrate the key technologies for the ERL, we constructed the Compact ERL (cERL)** from 2009 to 2013. In the cERL, high-brightness CW electron beams are produced using a 500-kV photocathode DC gun. The beams are accelerated using SC cavities, transported through a recirculation loop, decelerated in the SC cavities, and dumped. In the February of 2014, we succeeded in accelerating and recirculating the CW beams of 4.5 micro-amperes in the cERL; the beams were successfully transported from the gun to the beam dump under energy recovery operation in the main linac. Then, precise tuning of beam optics and diagnostics of beam properties are under way. We report our experience on the beam commissioning, as well as the results of initial measurements of beam properties. * N. Nakamura, IPAC2012, TUXB02. ** S. Sakanaka et al., IPAC2013, WEPWA015.

TUPOL02	4 K Alignment of Superconducting Quarter-Wave Cavities and 9 T Solenoids in the ATLAS Intensity Upgrade Cryomodule
TUPP003	use link to access more material from this paper's primary paper code
	S.H. Kim, Z.A. Conway, W.G. Jansma, M. Kedzie, M.P. Kelly, P.N. Ostroumov ANL, Argonne, Illinois, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357. The superconducting cavities and, especially, the magnets in high intensity ion linacs need to be aligned to the beam with typical transverse tolerances of 0.25 mm and 0.1 degrees at temperatures of 1.8 – 4.5 K. This is necessary to limit the emittance growth and minimize the beam losses. A new cryomodule with 7 superconducting quarter-wave resonators and 4 superconducting solenoids has been installed and is now operated at the Argonne Tandem Linear Accelerator System (ATLAS). We developed the techniques necessary to assemble the superconducting components in this cryomodule at room temperature so that they are aligned to the beam axis at 4.5 K. We achieved transverse alignment tolerances of <0.2 mm RMS. In this paper, we will present the details of the alignment hardware, procedures and results.
	Slides TUPOL02 [0.834 MB]

TUPOL03	Completion of Efficiency and Intensity Upgrade of the ATLAS Facility
TUPP005	use link to access more material from this paper's primary paper code
	P.N. Ostroumov, Z.A. Conway, C. Dickerson, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.H. Kim, Y. Luo, S.W.T. MacDonald, R.C. Murphy, B. Mustapha, R.C. Pardo, T. Reid, S.I. Sharamentov, K.W. Shepard, J.R. Specht, G.P. Zinkann ANL, Argonne, USA A. Perry Illinois Institute of Technology, Chicago, Illlinois, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. The ANL Physics Division has completed a major upgrade of the ATLAS National User Facility by successfully installing a new RFQ and cryomodule. The new normal conducting CW RFQ capable of providing 295 keV/u beams of any ion with m/q ≤7 from protons to uranium was fully integrated into ATLAS and has been in routine operation for more than a year. The RFQ doubled the efficiency of beam delivery to targets and opened the possibility to accelerate much higher intensity beams. Recently, the new cryomodule containing 7 high-performance 72.75 MHz superconducting quarter-wave resonators and 4 superconducting solenoids was successfully commissioned with beam. New design and fabrication techniques for these resonators resulted in record high voltages which were achieved during the beam commissioning. The new cryomodule provides 17.5 MV accelerating voltage which will be gradually raised by increasing the input RF power and improving LLRF system. The new cryomodule, which replaced 3 old cryomodules that used split-ring cavities, is also essential for high intensity stable beams. Results of beam commissioning and operation of ATLAS with the new RFQ and cryomodule will be presented.

TUPOL04	Beam Physics Challenge in FRIB Driver Linac
TUPP045	use link to access more material from this paper's primary paper code
	Y. Yamazaki, N.K. Bultman, A. Facco, Z.Q. He, M. Ikegami, M.J. Johnson, S.M. Lidia, F. Marti, G. Pozdeyev, K. Saito, J. Wei, X. Wu, Y. Zhang, Q. Zhao FRIB, East Lansing, Michigan, USA
	Funding: *Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The Facility for Rare Isotope Beams driver linac provides CW beams of all the stable ions (from protons to uranium) with a beam power of 400 kW and a minimum beam energy of 200 MeV/u in order to produce a wide variety of rare isotopes, mainly for nuclear physics study. The low beam emittances, both transverse and longitudinal, are key performance requirements, together with beam stability. These are required for efficiently separating one isotope from another, the reason for choosing this linac configuration. Multi-charge states (five charge states for the uranium case) are accelerated for maximizing the beam current, while keeping the low emittances. The efficient acceleration of high beam currents from 0.5 MeV/u through the superconducting linac is, needless to say, one of the biggest challenges. The beam power is more than 200 times higher than existing similar SC heavy ion linac. In particular, the SC cavities are difficult to protect from heavy ion beam damage, which can be 30 times larger locally than a proton beam with the same beam power. Other challenges peculiar to the FRIB linac will be presented, together with the solutions.

TUPOL05	Study of the ACS Cavity Without a Bridge Cavity
TUPP073	use link to access more material from this paper's primary paper code
	F. Naito, K. Takata KEK, Ibaraki, Japan H. Ao, K. Hasegawa, K. Hirano, T. Morishita, N. Ouchi JAEA/J-PARC, Tokai-mura, Japan
	J-PARC has installed the Annular-ring Coupled Structure (ACS) linac to increase the beam energy up to 400 MeV. One ACS module is composed of two accelerating tanks which are coupled by the bridge cavity. The bridge cavity simplifies the handling of the multi-tank system. While it is possible to feed the RF power into the each tanks directly with the power divider and the phase shifter instead of the bridge cavity. The rf properties of the ACS linac with the direct rf-power supply system has been measured by using the low power model made of aluminum. The measured results are described in the paper.
	Slides TUPOL05 [5.042 MB]

TUPOL06	Spatially Periodic RF Quadrupole LINAC
TUPP090	use link to access more material from this paper's primary paper code
SUPG013	use link to access more material from this paper's primary paper code
	A.S. Plastun, A. Kolomiets ITEP, Moscow, Russia
	Spatially-periodic RF quadrupole structure is proposed as second section of front end of ion linac. It consists of conventional drift tubes and RF quadrupoles. Quadrupoles are 4-vane segments with nonzero electric potential on the longitudinal axis. Thus the accelerating electric field is formed between drift tubes and RF quadrupoles. Moreover accelerating field can be provided even inside the RF quadrupoles. It allows building structures with different focusing lattices and provides high energy gain rate.

TUPOL07	Operation Of The Versatile Accelerator Driving the Low Power ADS GUINEVERE at SCK•CEN
TUPP100	use link to access more material from this paper's primary paper code
	M.A. Baylac, A. Billebaud, P. Boge, D. Bondoux, J. Bouvier, S. Chabod, G. Dargaud, E. Froidefond, E. Labussière, R. Micoud, S. Rey LPSC, Grenoble Cedex, France A. Kochetkov, J. Mertens, F. Van Gestel, C. Van Grieken, B. Van Houdt, G. Vittiglio SCK•CEN, Mol, Belgium F.R. Lecolley, J.L. Lecouey, G. Lehaut, N. Marie-Nourry CNRS/IN2P3/LPC CAEN, Caen, France
	GUINEVERE provides a low power accelerator driven system (ADS) to investigate on-line reactivity monitoring and operational procedures of an ADS. It consists of a versatile neutron source, GENEPI-3C, driving the fast sub-critical core, VENUS-F, in SCK•CEN (Belgium). GENEPI-3C is an electrostatic accelerator generating 14 MeV neutrons by bombarding a 250 keV deuteron beam onto a tritium target located within the reactor core. This accelerator produces alternatively continuous beam (up to 1 mA DC), possibly chopped with fast and adjustable interruptions, or short and intense deuteron bunches (~25 mA peak, 1 μs). This paper presents the facility and assesses the 2 years of coupled operation of the accelerator to the reactor.
	Slides TUPOL07 [0.969 MB]

TUPOL08	Effect of Beam-Loading on the Breakdown Rate of High Gradient Accelerating Structures
TUPP033	use link to access more material from this paper's primary paper code
	J.L. Navarro Quirante, R. Corsini, A. Degiovanni, S. Döbert, A. Grudiev, O. Kononenko, G. McMonagle, S.F. Rey, A. Solodko, I. Syratchev, F. Tecker, L. Timeo, B.J. Woolley, X.W. Wu, W. Wuensch CERN, Geneva, Switzerland O. Kononenko SLAC, Menlo Park, California, USA A. Solodko JINR, Dubna, Moscow Region, Russia J. Tagg National Instruments Switzerland, Ennetbaden, Switzerland B.J. Woolley Cockcroft Institute, Lancaster University, Lancaster, United Kingdom X.W. Wu TUB, Beijing, People's Republic of China
	The Compact Linear Collider (CLIC) is a study for a future room temperature electron-positron collider with a maximum center-of-mass energy of 3 TeV. To efficiently achieve such high energy, the project relies on a novel two beam acceleration concept and on high-gradient accelerating structures working at 100 MV/m. In order to meet the luminosity requirements, the break-down rate in these high-field structures has to be kept below 10 per billion. Such gradients and breakdown rates have been demonstrated by high-power RF testing several 12 GHz structures. However, the presence of beam-loading modifies the field distribution for the structure, such that a higher input power is needed in order to achieve the same accelerating gradient as the unloaded case. The potential impact on the break-down rate was never measured before. In this paper we present an experiment located at the CLIC Test Facility CTF3 recently proposed in order to quantify this effect, layout and hardware status, and discuss its first results.
	Slides TUPOL08 [1.970 MB]

TUPOL09	Tuning and Field Stabilization of the CERN Linac4 Drift Tube Linac
TUPP089	use link to access more material from this paper's primary paper code
SUPG018	use link to access more material from this paper's primary paper code
	M.R. Khalvati IPM, Tehran, Iran S. Ramberger CERN, Geneva, Switzerland
	The Drift Tube Linac (DTL) for the new linear accelerator Linac4 at CERN will accelerate H–beams of up to 40 mA average pulse current from 3 to 50 MeV. The structure consists of three cavities. The first cavity (Tank1) is a 3.9 m long tank containing 38 drift tubes, 10 fixed tuners, 2 movable tuners and 12 post-couplers, operating at a frequency of 352.2 MHz and an average accelerating field of 3.1 MV/m. This paper reports on the results and procedures used for the low–power tuning, stabilization and power coupler tuning carried out on the first Linac4 DTL tank. The upgrade of the bead pull measurement system and twists to the well-known tilt sensitivity technique are discussed.

TUPOL10	Design of Novel RF Sources to Reduce the Beam Pace-Charge Effects
TUPP123	use link to access more material from this paper's primary paper code
	M. Dal Forno, A. Jensen, R.D. Ruth, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: DOE Traditional RF sources, such as Klystrons, TWT require a magnet (such as a solenoid) in order to maintain the electron beam focusing, compensating the particle repulsion caused by space charge effects. We designed a novel RF source with an alternative approach that reduces beam space charge problems. This paper shows the design of the device, with a new formulation of the Child’s Law, and the mode-beam stability analysis. The electron beam interaction with the cavity fields has been analyzed by means of particle tracking software in order to evaluate the beam bunching and the beam dynamics.

TUPOL011	RF Input Power Couplers for High Current SRF Applications
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	V.F. Khan, W. Anders, A. Burrill, J. Knobloch, O. Kugeler, A. Neumann HZB, Berlin, Germany H. Wang JLab, Newport News, Virginia, USA
	High current SRF technology is being explored in present day accelerator science. The BERLinPro project is presently being built at the HZB to address the challenges involved in high current SRF machines. A 100 mA electron beam is designed to be accelerated to 50 MeV in continuous wave (cw) mode at 1.3 GHz. One of the main challenges in this project is that of handling high input RF power for the gun as well as booster cavities where there is no energy recovery process. A high power co-axial input coupler is being developed to be used for the booster and gun cavities at the nominal beam current. The coupler is based on the KEK–cERL coupler design. The KEK coupler design has been modified to minimise the penetration of the tip in the beampipe without compromising on beam-power coupling ( Qext ~1 x 105). Herein we report on the RF design for the high power (130 kW) BERLinPro (BP) couplers along with the test stand for conditioning the couplers. We will also report on the RF conditioning of the TTF-III couplers modified for cw operation (low power ~ 10 kW) which will be utilised in a new 4-mA SRF Photoinjector and the BERLinPro main linac cryomodule.
	Slides TUPOL011 [2.465 MB]

TUPOL012	Space Charge Compensation in the Linac4 LEBT for Three Injected Gas Types
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SUPG028	use link to access more material from this paper's primary paper code
	C.A. Valerio, R. Scrivens CERN, Geneva, Switzerland N. Chauvin CEA/IRFU, Gif-sur-Yvette, France
	The space charge of unbunched, high intensity beams can be compensated by the trapping of charged particles in the potential well of the beam. The source of these secondary charge particles can be the residual gas in the beam line. The effect is important in the Low energy beam transport (LEBT) regions. At CERN’s Linac4, the LEBT transports a pulsed 45keV H⁻ beam, which is compensated by the positive ions, created by collision of the beam with the neutral gas in the beam pipe. The rise time and amount of compensation may be varied by the density of neutral gas and the type of gas used (through the cross-section for ion production and the mass of the resulting ion). In this paper we present measurement results for the transport of the beam at the Linac4 LEBT with the addition of hydrogen, nitrogen and krypton gases into the line, and compare them with simulations of the beam dynamics including the effect of compensating positive ions . The H⁻ beam is provided by a cesiated 2MHz RF ion source with an external solenoidal antenna, operating with 600us pulses at 0.8Hz repetition rate.
	Slides TUPOL012 [4.084 MB]