| Paper |
Title |
Page |
| MOPCH186 |
First Cool Down of the Juelich Accelerator Module Based on Superconducting Half-Wave Resonators
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496 |
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- F.M. Esser, B. Laatsch, H.S. Singer, R. Stassen
FZJ, Jülich
- R. Eichhorn
TU Darmstadt, Darmstadt
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In the context of upgrading the existing proton and deuteron accelerator facility COSY at the Forschungszentrum Juelich, an accelerator module based on superconducting half wave resonators is prototyped. Due to beam dynamics, the requirements of cavity operation and a top-loading design for mounting, the cryostat had to be designed very compact and with a separate vacuum system for beam and insulation vacuum. These restricted requirements lead to very short cold-warm transitions in beam port region and to an unconventional design regarding to the shape of the cryostat vessel. This paper will review the design constraints, gives an overview of the ancillary parts of the module (cavities, tuner, etc.) and will present the results of the first cool-down experiments. Furthermore the future work will be presented.
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| MOPCH187 |
Key Cryogenics Challenges in the Development of the 4GLS
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499 |
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- R. Bate, R.K. Buckley, A.R. Goulden, C. Hodgkinson, S.M. Pattalwar
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
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The fourth generation light source (4GLS) is a uniquely flexible source of ultra-high brightness continuous and pulsed radiation covering the IR to XUV range of the spectrum. It is the first light source in the world that is planned from the outset to be a multi-user, multi-source facility combining ERL (energy recovery LINAC) and FEL (free electron laser) technology. 4GLS will require six different sets of superconducting LINACs. Each of the LINAC modules consists of 2 to 7, 1.3 GHz superconducting RF cavities of the TESLA design operating at 1.8 K. The overall cooling power necessary to cool the cavities is estimated to be around 2.5KW demanding the superfluid liquid helium flow rates in excess of 200g/s. Even though the technology of the superconducting RF cavities is somewhat well understood, the design and subsequent operation of the cryogenic system / Cryo modules is an extremely complex task. In this paper we describe the key cryogenic challenges of the 4GLS project and our approach in identifying solutions to meet them.
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| MOPCH189 |
Calculating the Muon Cooling within a MICE Liquid Absorber
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502 |
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- M.A. Green, S.P. Virostek
LBNL, Berkeley, California
- S.Q. Yang
OXFORDphysics, Oxford, Oxon
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The key elements of the Muon Ionization Cooling Experiment (MICE) cooling channel are the absorbers that are a part of the MICE absorber focus coil modules (AFC modules). The boundaries of room temperature solid absorbers are well defined. The density of most solid absorber materials is also well understood. The properties of solid absorber are most certainly understood to 0.3 percent. The MICE liquid absorbers are different in that their dimensions are a function of the absorber temperature and the fluid pressure within the absorber. The second element in the liquid absorber is the variability of the liquid density with temperature and pressure. While one can determine the absorber boundary within 0.3 percent, the determination of the liquid density within 0.3 percent is more difficult (particularly with liquid helium in the absorber). This report presents a method of calculating absorber boundary and the cooling performance of the MICE absorbers as a function of fluid temperature and pressure.
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| MOPCH190 |
Cryomodule Development for Superconducting RF Test Facility (STF) at KEK
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505 |
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- K. Tsuchiya, H. Hayano, Y. Higashi, H. Hisamatsu, M. Masuzawa, H. Matsumoto, C. Mitsuda, S. Noguchi, N. Ohuchi, T. Okamura, K. Saito, A. Terashima, N. Toge
KEK, Ibaraki
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Current status of the cryomodule development for superconducting RF test facility, STF, at KEK is presented. The objective of the STF construction is to have an experience of 5-m long cryomodule fabrications and to learn an operational method of superconducting RF cavities. The STF consists of two 5-m long cryomodules, each housing four 9-cell cavities (one for 35 MV/m and the other for 45 MV/m). In addition to the cavity type, each cavity has variations in its appendices. Thus, two cryomodules must have different structures for the cavity support and for the port of the RF input coupler. This paper describes the details of the cryomodule design, the development of the bimetallic joint for connecting the titanium helium vessel to the stainless steel cooling pipe, and the studies of the magnetic shielding for high quality cavities.
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| MOPCH191 |
Copper Heat Exchanger for the External Auxiliary Bus-bars Routing Line in the LHC Insertion Regions
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508 |
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- C. Garion, A. Poncet, F. Seyvet, J.-P.G. Tock
CERN, Geneva
- M. Sitko, B. Skoczen
CUT, Krakow
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The corrector magnets and the main quadrupoles of the LHC dispersion suppressors are powered by a special superconducting line (called auxiliary bus-bars line N), external to the cold mass and housed in a 50 mm diameter stainless steel tube fixed to the cold mass. As the line is periodically connected to the cold mass, the same gaseous and liquid helium is used for cooling the magnets and the line. The final sub-cooling process (from 4.5 K down to 1.9 K) consists of the phase transformation from liquid to superfluid helium. It is slightly delayed with respect to the magnets. To accelerate the process, a special heat exchanger has been designed. Located in the middle of the dispersion suppressor portion of the line it consists in creating a local sink of heat extraction, providing two additional λ fronts that propagate in opposite directions towards the line extremities. Both the numerical model and the sub-cooling analysis are presented in the paper for different configurations of the line. Design, manufacturing and integration aspects of the heat exchanger are described. Finally, the results of the qualification tests and the expected performance of the line are given.
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| MOPCH192 |
Operation of a Helium Cryogenic System for a Superconducting Cavity in an Electron Storage Ring
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511 |
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- F. Z. Hsiao, S.-H. Chang, W.-S. Chiou, H.C. Li
NSRRC, Hsinchu
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A 500 MHz superconducting cavity maintaining the energy of electrons in the storage ring of TLS light source started from the year 2005. A helium system dedicated to keep the niobium cavity at 4.5 K has begun its operation since the year 2003. The cryogenic system provides maximum refrigeration of 469 W or liquefaction rate of 134 l/hr. The constraint from the superconducting cavity leads to specific features of the cryogenic system. This paper presents the operation of the cryogenic system as the superconducting cavity at different conditions. The interaction in between the cryogenic system and the superconducting cavity and the constraints on the starting and shutdown of the cryogenic system are indicated.
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| MOPCH193 |
SNS 2.1K Cold Box Turn-down Studies
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514 |
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- F. Casagrande, P.A. Gurd, D.R. Hatfield, M.P. Howell, W.H. Strong
ORNL, Oak Ridge, Tennessee
- D. Arenius, J. Creel, V. Ganni, P. Knudsen
Jefferson Lab, Newport News, Virginia
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The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory is nearing completion. The cold section of the Linac consists of 81 superconducting radio frequency cavities cooled to 2.1K by a 2400 watt cryogenic refrigeration system. The 2.1K cold box consists of four stages of centrifugal compressors with LN2-cooled variable speed electric motors and magnetic bearings. The cryogenic system successfully supported the Linac beam commissioning at both 4.2K and 2.1K and has been fully operational since June 2005. This paper describes the control principles utilized and the experimental results obtained for the SNS cold compressors turn-down capability to about 30% of the design flow, and possible limitation of the frequency dependent power factor of the cold compressor electric motors, which was measured for the first time during commissioning. These results helped to support the operation of the Linac over a very broad and stable cold compressor operating flow range (refrigeration capacity) and pressure. This in turn helped to optimise the cryogenic system operating parameters, minimizing the utilities and improving the system reliability and availability.
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| FRXCPA01 |
Design, Construction, Installation and First Commissioning Results of the LHC Cryogenic System
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3626 |
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- S.D. Claudet
CERN, Geneva
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The cryogenic system of the Large Hadron Collider (LHC) will be, upon its completion in 2006, the largest in the world in terms of refrigeration capacity with 140 kW at 4.5 K, distributed superfluid helium with 25 km of superconducting magnets below 2 K and cryogen inventory with 100 tons of Helium. The challenges involved in the design, construction and installation, as well as the first commissioning results will be addressed in this talk. Particular mention will be made of the problems encountered and how they were or are being solved. Perspectives for LHC will be presented. General considerations for future large cryogenic systems will be briefly proposed.
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Transparencies
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