IPAC2011 - List of Authors (Schwerg, N.)

Paper

Title

Page

Practical Test of the Linac4 RF Power System

403

N. Schwerg, O. Brunner
CERN, Geneva, Switzerland

Linac4 is a linear accelerator for negative Hydrogen ions which will replace the old Linac2 as injector for the CERN accelerators. Its higher energy of 160 MeV will increase the beam intensity in the downstream machines. The normal-conducting accelerating structures are housed in a 100 m long tunnel which will be connected to the existing chain of accelerators and can be extended into a new injector chain. The high RF power for the Linac4 accelerating structures will be generated by thirteen 1.3 MW klystrons, previously used for the CERN LEP accelerator, and six new klystrons of 2.8 MW all operating at a frequency of 352.2 MHz. The re-use of existing LEP equipment, space limitations in the installation and tight phase and amplitude constraints pose a number of challenges for the integration of the RF power system. The power distribution scheme features a folded magic-tee feeding the power from a 2.8 MW klystron to two LEP circulators. We present first results from the Linac4 test place, validating the approach and the used components as well as reporting on the klystron re-tuning activities.

TUPS072

Performance of the Arc Detectors of LHC High Power RF System

1704

D. Valuch, O. Brunner, N. Schwerg
CERN, Geneva, Switzerland

During operation, the LHC high power RF equipment, such as klystrons, circulators, waveguides and couplers have to be protected from damage caused by electromagnetic discharges. Once ignited these arcs grow over the full height of the waveguide and travel towards the RF source. The burning plasma can cause serious damage to the metal surfaces or ferrite materials. The LHC arc detector system is based on the optical detection of the discharge through small apertures in the waveguide walls. The light is guided by means of an optical fibre from the view port to a photo diode. Experience shows that some of the currently used optical fibers suffer from x-ray induced opacity. The sensors are also exposed to the radiation produced by secondary showers coming from the high intensity beams which, if not treated properly, can cause frequent spurious trips. In the second half of the paper we presents a number of improvements to the design. Measurements with optical parameters from real arcs and a fiber-less version of the detector with redundant detectors for critical environments.

TUOAA03

The Linac4 Project at CERN

900

M. Vretenar, L. Arnaudon, P. Baudrenghien, C. Bertone, Y. Body, J.C. Broere, O. Brunner, M.C.L. Buzio, C. Carli, F. Caspers, J.-P. Corso, J. Coupard, A. Dallocchio, N. Dos Santos, R. Garoby, F. Gerigk, L. Hammouti, K. Hanke, M.A. Jones, I. Kozsar, J.-B. Lallement, J. Lettry, A.M. Lombardi, L.A. Lopez Hernandez, C. Maglioni, S.J. Mathot, S. Maury, B. Mikulec, D. Nisbet, C. Noels, M.M. Paoluzzi, B. Puccio, U. Raich, S. Ramberger, C. Rossi, N. Schwerg, R. Scrivens, G. Vandoni, J. Vollaire, S. Weisz, Th. Zickler
CERN, Geneva, Switzerland

As the first step of a long-term programme aiming at an increase in the LHC luminosity, CERN is building a new 160 MeV H⁻ linear accelerator, Linac4, to replace the ageing 50 MeV Linac2 as injector to the Proton-Synchrotron Booster (PSB). Linac4 is an 86-m long normal-conducting linac made of an H⁻ source, a Radio Frequency Quadrupole (RFQ), a chopping line and a sequence of three accelerating structures: a Drift-Tube Linac (DTL), a Cell-Coupled DTL (CCDTL) and a Pi-Mode Structure (PIMS). The civil engineering has been recently completed, and construction of the main accelerator components has started with the support of a network of international collaborations. The low-energy section up to 3 MeV including a 3-m long 352 MHz RFQ entirely built at CERN is in the final construction phase and is being installed on a dedicated test stand. The present schedule foresees beam commissioning of the accelerator in the new tunnel in 2013/14; the moment of connection of the new linac to the CERN accelerator chain will depend on the LHC schedule for long shut-downs.

Slides TUOAA03 [10.347 MB]

Paper	Title	Page
MOPC138	Practical Test of the Linac4 RF Power System	403
	N. Schwerg, O. Brunner CERN, Geneva, Switzerland
	Linac4 is a linear accelerator for negative Hydrogen ions which will replace the old Linac2 as injector for the CERN accelerators. Its higher energy of 160 MeV will increase the beam intensity in the downstream machines. The normal-conducting accelerating structures are housed in a 100 m long tunnel which will be connected to the existing chain of accelerators and can be extended into a new injector chain. The high RF power for the Linac4 accelerating structures will be generated by thirteen 1.3 MW klystrons, previously used for the CERN LEP accelerator, and six new klystrons of 2.8 MW all operating at a frequency of 352.2 MHz. The re-use of existing LEP equipment, space limitations in the installation and tight phase and amplitude constraints pose a number of challenges for the integration of the RF power system. The power distribution scheme features a folded magic-tee feeding the power from a 2.8 MW klystron to two LEP circulators. We present first results from the Linac4 test place, validating the approach and the used components as well as reporting on the klystron re-tuning activities.

TUPS072	Performance of the Arc Detectors of LHC High Power RF System	1704
	D. Valuch, O. Brunner, N. Schwerg CERN, Geneva, Switzerland
	During operation, the LHC high power RF equipment, such as klystrons, circulators, waveguides and couplers have to be protected from damage caused by electromagnetic discharges. Once ignited these arcs grow over the full height of the waveguide and travel towards the RF source. The burning plasma can cause serious damage to the metal surfaces or ferrite materials. The LHC arc detector system is based on the optical detection of the discharge through small apertures in the waveguide walls. The light is guided by means of an optical fibre from the view port to a photo diode. Experience shows that some of the currently used optical fibers suffer from x-ray induced opacity. The sensors are also exposed to the radiation produced by secondary showers coming from the high intensity beams which, if not treated properly, can cause frequent spurious trips. In the second half of the paper we presents a number of improvements to the design. Measurements with optical parameters from real arcs and a fiber-less version of the detector with redundant detectors for critical environments.

TUOAA03	The Linac4 Project at CERN	900
	M. Vretenar, L. Arnaudon, P. Baudrenghien, C. Bertone, Y. Body, J.C. Broere, O. Brunner, M.C.L. Buzio, C. Carli, F. Caspers, J.-P. Corso, J. Coupard, A. Dallocchio, N. Dos Santos, R. Garoby, F. Gerigk, L. Hammouti, K. Hanke, M.A. Jones, I. Kozsar, J.-B. Lallement, J. Lettry, A.M. Lombardi, L.A. Lopez Hernandez, C. Maglioni, S.J. Mathot, S. Maury, B. Mikulec, D. Nisbet, C. Noels, M.M. Paoluzzi, B. Puccio, U. Raich, S. Ramberger, C. Rossi, N. Schwerg, R. Scrivens, G. Vandoni, J. Vollaire, S. Weisz, Th. Zickler CERN, Geneva, Switzerland
	As the first step of a long-term programme aiming at an increase in the LHC luminosity, CERN is building a new 160 MeV H⁻ linear accelerator, Linac4, to replace the ageing 50 MeV Linac2 as injector to the Proton-Synchrotron Booster (PSB). Linac4 is an 86-m long normal-conducting linac made of an H⁻ source, a Radio Frequency Quadrupole (RFQ), a chopping line and a sequence of three accelerating structures: a Drift-Tube Linac (DTL), a Cell-Coupled DTL (CCDTL) and a Pi-Mode Structure (PIMS). The civil engineering has been recently completed, and construction of the main accelerator components has started with the support of a network of international collaborations. The low-energy section up to 3 MeV including a 3-m long 352 MHz RFQ entirely built at CERN is in the final construction phase and is being installed on a dedicated test stand. The present schedule foresees beam commissioning of the accelerator in the new tunnel in 2013/14; the moment of connection of the new linac to the CERN accelerator chain will depend on the LHC schedule for long shut-downs.
	Slides TUOAA03 [10.347 MB]