120 research outputs found
Optimisation of ITER Nb3Sn CICCs for coupling loss, transverse electromagnetic load and axial thermal contraction
The ITER cable-in-conduit conductors (CICCs) are built up from sub-cable
bundles, wound in different stages, which are twisted to counter coupling loss
caused by time-changing external magnet fields. The selection of the twist
pitch lengths has major implications for the performance of the cable in the
case of strain sensitive superconductors, i.e. Nb3Sn, as the electromagnetic
and thermal contraction loads are large but also for the heat load from the AC
coupling loss. Reduction of the transverse load and warm-up cool-down
degradation can be reached by applying longer twist pitches in a particular
sequence for the sub-stages, offering a large cable transverse stiffness,
adequate axial flexibility and maximum allowed lateral strand support. Analysis
of short sample (TF conductor) data reveals that increasing the twist pitch can
lead to a gain of the effective axial compressive strain of more than 0.3 %
with practically no degradation from bending. For reduction of the coupling
loss, specific choices of the cabling twist sequence are needed with the aim to
minimize the area of linked strands and bundles that are coupled and form loops
with the applied changing magnetic field, instead of simply avoiding longer
pitches. In addition we recommend increasing the wrap coverage of the CS
conductor from 50 % to at least 70 %. The models predict significant
improvement against strain sensitivity and substantial decrease of the AC
coupling loss in Nb3Sn CICCs, but also for NbTi CICCs minimization of the
coupling loss can be achieved. Although the success of long pitches to
transverse load degradation was already demonstrated, the prediction of the
combination with low coupling loss needs to be validated by a short sample
test.Comment: to be published in Supercond Sci Techno
Test Results from the PF Conductor Insert Coil and Implications for the ITER PF System
In this paper we report the main test results obtained on the Poloidal Field Conductor Insert coil (PFI) for the International Thermonuclear Experimental Reactor (ITER), built jointly by the EU and RF ITER parties, recently installed and tested in the CS Model Coil facility, at JAEA-Naka. During the test we (a) verified the DC and AC operating margin of the NbTi Cable-in-Conduit Conductor in conditions representative of the operation of the ITER PF coils, (b) measured the intermediate conductor joint resistance, margin and loss, and (c) measured the AC loss of the conductor and its changes once subjected to a significant number of Lorentz force cycles. We compare the results obtained to expectations from strand and cable characterization, which were studied extensively earlier. We finally discuss the implications for the ITER PF system
Tau Interaction with Tubulin and Microtubules: From Purified Proteins to Cells
International audienceMicrotubules (MTs) play an important role in many cellular processes and are dynamic structures regulated by an important network of microtubules-associated proteins, MAPs, such as Tau. Tau has been discovered as an essential factor for MTs formation in vitro, and its region implicated in binding to MTs has been identified. By contrast, the affinity, the stoichiometry, and the topology of Tau-MTs interaction remain controversial. Indeed, depending on the experiment conditions a wide range of values have been obtained. In this chapter, we focus on three biophysical methods, turbidimetry, cosedimentation assay, and Förster Resonance Energy Transfer to study Tau-tubulin interaction both in vitro and in cell. We highlight precautions that must be taken in order to avoid pitfalls and we detail the nature of the conclusions that can be drawn from these methods about Tau-tubulin interaction
The CARE accelerator R&D programme in Europe
Published online on JACoWCARE, an ambitious and coordinated programme of accelerator research and developments oriented towards high energy physics projects, has been launched in January 2004 by the main European laboratories and the European Commission. This project aims at improving existing infrastructures dedicated to future projects such as linear colliders, upgrades of hadron colliders and high intensity proton drivers. We describe the CARE R&D plans, mostly devoted to advancing the performance of the superconducting technology, both in the fields of RF cavities for electron or proton acceleration and of high field magnets, as well as to developing high intensity electron and proton injectors. We highlight some results and progress obtained so far
Power Test of the First Two HL-LHC Insertion Quadrupole Magnets Built at CERN
The High-Luminosity project (HL-LHC) of the
CERN Large Hadron Collider (LHC), requires low β* quadrupole
magnets in NbSn technology that will be installed on each side
of the ATLAS and CMS experiments. After a successful shortmodel magnet manufacture and test campaign, the project has
advanced with the production, assembly, and test of full-size 7.15-
m-long magnets. In the last two years, two CERN-built prototypes
(MQXFBP1 and MQXFBP2) have been tested and magnetically
measured at the CERN SM18 test facility. These are the longest
accelerator magnets based on NbSn technology built and tested
to date. In this paper, we present the test and analysis results
of these two magnets, with emphasis on quenches and training,
voltage-current measurements and the quench localization with
voltage taps and a new quench antenna
Development of HTS Current Leads for the ITER Project
The HTS current leads for the ITER project will be the largest ever operated, with unprecedented currents, up to 68 kA and voltages, up to 14 kV. According to the ITER agreement they will be provided in-kind by China. After an extensive development program at the Hefei Institute of Plasma Physics (ASIPP), the ITER current leads were designed and qualified. The following discusses the main highlights of this development, with particular emphasis on the description of the design of the different types of ITER current leads and their final qualification in dedicated cold tests in nominal conditions
Phytoplankton functional types from Space.
The concept of phytoplankton functional types has emerged as a useful approach to
classifying phytoplankton. It finds many applications in addressing some serious
contemporary issues facing science and society. Its use is not without challenges,
however. As noted earlier, there is no universally-accepted set of functional types,
and the types used have to be carefully selected to suit the particular problem being
addressed. It is important that the sum total of all functional types matches all
phytoplankton under consideration. For example, if in a biogeochemical study,
we classify phytoplankton as silicifiers, calcifiers, DMS-producers and nitrogen fix-
ers, then there is danger that the study may neglect phytoplankton that do not
contribute in any significant way to those functions, but may nevertheless be a
significant contributor to, say primary production. Such considerations often lead
to the adoption of a category of “other phytoplankton” in models, with no clear
defining traits assigned them, but that are nevertheless necessary to close budgets
on phytoplankton processes. Since this group is a collection of all phytoplankton
that defy classification according to a set of traits, it is difficult to model their physi-
ological processes. Our understanding of the diverse functions of phytoplankton is
still growing, and as we recognize more functions, there will be a need to balance the
desire to incorporate the increasing number of functional types in models against
observational challenges of identifying and mapping them adequately. Modelling
approaches to dealing with increasing functional diversity have been proposed,
for example, using the complex adaptive systems theory and system of infinite
diversity, as in the work of Bruggemann and Kooijman (2007). But it is unlikely that
remote-sensing approaches might be able to deal with anything but a few prominent
functional types. As long as these challenges are explicitly addressed, the functional-
type concept should continue to fill a real need to capture, in an economic fashion,
the diversity in phytoplankton, and remote sensing should continue to be a useful
tool to map them.
Remote sensing of phytoplankton functional types is an emerging field, whose
potential is not fully realised, nor its limitations clearly established. In this report,
we provide an overview of progress to date, examine the advantages and limitations
of various methods, and outline suggestions for further development. The overview
provided in this chapter is intended to set the stage for detailed considerations of
remote-sensing applications in later chapters.
In the next chapter, we examine various in situ methods that exist for observing
phytoplankton functional types, and how they relate to remote-sensing techniques.
In the subsequent chapters, we review the theoretical and empirical bases for the
existing and emerging remote-sensing approaches; assess knowledge about the
limitations, assumptions, and likely accuracy or predictive skill of the approaches;
provide some preliminary comparative analyses; and look towards future prospects
with respect to algorithm development, validation studies, and new satellite mis-
sions
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