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confirmed that the characteristics of an HTS tape could be
varied certainly by neighboring HTS conductors. It is
necessary to study the function of neighboring HTS
conductors that do not flow current. This paper deals with
measurement of the critical currents and the transport
current losses of HTS tapes with neighboring HTS
conductors. Measurement results and comparison will be
presented with discussions.
POSTER SESSION 13:30 – 15:30
LHC MISCELLANEOUS MAGNETS
TUA06PO01
Normal-Conducting Separation and Compensation
Dipoles for the LHC Experimental Insertions
S. Ramberger, D. Gerard, D. Cornuet, G. de Rijk, CERN; I.
Morozov, V. Petrov, O. Kiselev, A. Sukhanov, E. Ruvinsky,
BINP.
The experimental insertions of the LHC employ normalconducting
magnets to provide for part of the beam
separation and to compensate the effect of two large
spectrometer dipoles. In the interaction regions IR1 for the
ATLAS experiment and IR5 for the CMS experiment, each
of the optical elements D1 for beam separation on either
side of the experiment consists of 6 MBXW dipoles. Each
magnet has a core length of 3.4 m, a large single aperture
with a gap height of 63 mm and will operate in the field
range up to 1.5 T. The MBXWT and MBXWS magnets are
shorter versions of the MBXW magnet and will be used as
vertical and horizontal compensation dipoles for the
spectrometer dipoles in IR2 for the ALICE and in IR8 for
the LHCb experiments respectively. The MBXWT and
MBXWS magnets have a core length of 1.5m and 0.75m
respectively. Additionally one MBXW magnet serves as a
main compensator for the LHCb experiment. The magnet
design was done in collaboration between CERN and BINP
and the dipole magnets are produced by BINP. So far all
three MBXWS, all three MBXWT and thirteen of twentynine
MBXW magnets have been manufactured and
delivered to CERN. The report presents the main design
issues and results of the acceptance tests including
mechanical, electrical and magnetic field measurements.
TUA06PO02
Transient Thermal Analysis of Normal-Conducting
Accelerator Magnets for the LHC
S. Ramberger, S. Bidon, D. Gerard, O. Hans, CERN.
The cleaning insertions of the LHC consist of a series of
normal-conducting magnets. Their heat has to be extracted
by water cooling and air ventilation systems to keep the
tunnel temperature at the prescribed level. Plans to confine
the collimation region including the magnets, called for a
more detailed transient thermal model to evaluate the
necessary ventilation within this area. This report
investigates the thermal behaviour of the MQW double
aperture quadrupole magnet in particular. A series of 6
magnets of this type establish an optical
focusing/defocusing element in the LHC lattice of the
cleaning insertions. The aim of this work is to set up a
straightforward model that allows for the study of the
transient temperatures of the coils, the cooling water, the
yoke, the air, and the resulting heat flows. The basis for the
model is an equivalent electric circuit which is evaluated by
a SPICE circuit simulator. It is shown how to derive
resistances and capacitances from analytic formulas for
each of the circuit elements taking their shape and
properties into account. The comparison of the simulation
results with temperature measurements on the coils and
the yoke of the magnet confirm the lumped circuit model. It
is also shown that the model reflects particular behaviour
following transient current changes. It is therefore capable
of predicting complex transient temperature profiles
resulting from its environment.
TUA06PO03
Field Quality Change in Accelerator Magnets Due to
Re-Magnetization of Superconductor
K. Sugita, The Graduate University for Advanced Studies;
T. Ogitsu, N. Ohuchi, T. Nakamoto, K. Tsuchiya, C.
Shintomi, A. Yamamoto, KEK.
A simulation program was developed to compute change of
magnetic field quality originated by inter-strand current
redistribution in Rutherford cables. The program was based
on a hypothesis that the magnetic field quality is drifted by
changing of superconductor filament magnetizations due to
local field changes following imbalance current
redistributions, especially during periods of beam injection.
The imbalanced currents in cables were described by
random zigzag currents within limited current variation. A
sinusoidal magnetic field modulation, so called a 'periodic
pattern', and the local field on the strand were computed.
The variations of the filament magnetizations due to the
local field changes, which cause the change of field quality
in the magnet bore, were computed using a new model
consisting of multiple layers of persistent current having
cosine theta distribution. The computed results will be
reported in comparisons with the measured results from 18
superconducting quadrupole magnets (MQXAs) for the
LHC insertion regions.
TUA06PO04
Focusing strength measurements of the main
quadrupoles
N. Smirnov, L. Bottura, M. Buzio, M. Calvi, G. Deferne, O.
Dunkel, J. Garcia Perez, S. Sanfilippo, N. Sammut, CERN;
J. DiMarco, FNAL.
The 474 twin aperture superconducting quadrupole
magnets needed for the Large Hadron Collider (LHC) are
assembled in up to 12 m long cryostats. Because of the
‘warm-bore’ insert, there is only 40 mm of roomtemperature
measurement aperture available during
cryogenic tests, making the integrated gradient of the
quadrupoles challenging to measure both efficiently and
with the required 0.1% absolute accuracy. This contribution
describes the various systems used to perform magnetic
field testing: Automated Scanner system, Single Stretched
Wire system and Twin Coils system, concentrating mostly
on the absolute accuracies of their integrated gradient
(Gdl) measurements. Most of the possible inherent effects
that can introduce systematic errors are discussed, along
with their preventive methods. In understanding the
systematic errors, a few samples of each of the several
types of quadrupoles have been thoroughly measured with
the different systems. The results of these intersystem
cross-calibrations are presented. Also discussed are the
qualification results for the measurement systems used in
industry. This qualification is based on comparison of
results for several quadrupole assemblies tested both in
cold conditions at CERN and at room temperature at the
manufacturer site.
TUA06PO05
Electrical and Magnetic Performance of the LHC Short
Straight Sections
S. Sanfilippo, M. Buzio, M. Coccoli, N. Smirnov, N.
Sammut, A. Stafiniak, L. Bottura, P. Pugnat, A. Siemko, P.
MT-19 2005, Genova 66