accelerating-news-arc.web.cern.ch - US-LARP

Triplet magnets program progressing on both sides of the Atlantic

Panagiotis Charitos — Tue, 06 Dec 2016 11:19:36 +0000

Triplet magnets program progressing on both sides of the Atlantic
by G. Ambrosio, P. Ferracin, E. Todesco (CERN)

The Nb3Sn 150 mm aperture quadrupoles MQXF, to be installed in the inner triplets around ATLAS and CMS in 2024-5, are entering a critical phase; the first two 1.5-m-long models have been manufactured and tested since the beginning of this year.

This magnet development program, carried out as a joint effort between CERN and US LARP foresees the construction and testing of five 1.5-m-long models to validate the design and fine tune the assembly features during 2014-17.

These magnets rely on the Al shell and bladder&key structure, allowing easy and fast disassembly, and a precise tuning of the coil prestress. Mechanics is a critical part in the design of these large aperture quadrupoles, featuring an 11.4 T peak field in the coils (50% larger than the peak field in the LHC dipoles operating at 6.5 TeV).

The first model, MQXFS1, was assembled in the U.S. with two CERN coils and two LARP coils, and was confirmed to fulfil performance requirements in April 2016 (see Figure 1). The performance requirements included a) reaching the ultimate current (8% higher than the nominal current of 16.4 kA), and b) reaching nominal current after a thermal cycle with at most one quench.

Figure 1: Training of MQXFS1: quenches (markers), nominal and ultime current (solid lines) and short sample limit (dotted line). (Credit: HL-LHC WP3 collaboration)

The memory after thermal cycle has outperformed expectations by exceeding ultimate current in the first quench after the thermal cycle. However, training has been slower than expected, reaching nominal current after nine quenches. After this first cycle of testing, the transverse pre-stress in the magnet was increased by 30%, to ensure a better support to the coils.

In October 2016, the second assembly was tested at FNAL, reaching 18.8 kA; which is 15% more than the nominal current, and close to 90% of the maximum theoretical performance of the magnet. Some detraining has been observed sporadically, reducing the magnet performance but keeping it always well above the nominal current.

At 4.2 K the magnets shows the ability to reach the same current, thus demonstrating the existence of a considerable margin in temperature, meaning the magnet should tolerate local heating).

The second model, MQXFS3, (MQXFS2 has been postponed to 2017) has been tested at CERN in October 2016, using a novel test station (HFM) planned to be used for the Fresca II dipole.

The magnet reached nominal current with nine quenches, as MQXFS1, but reached a current only 4% above nominal after 20 quenches. A significantly larger detraining than in MQXFS1 was observed, pushing the magnet performance well below nominal (15.0 kA).

Nonetheless, the maximal performance of 17.2 kA has been recovered after ramp rate tests. In addition, 4.2 K test, shows the same performance reached at 2.1 K and also demonstrates the existence of a considerable temperature margin.

Training of MQXFS3: quenches (markers), nominal and ultimate current (solid lines) and short sample limit (dotted line). (Credit: HL-LHC WP3 collaboration)

Work is now focussed on understanding the relationship between the quenches and the mechanical structure. As quenches are mainly located in the coil heads the longitudinal preload will be increased. Further testing after the thermal cycle is expected for the end of the year and . three additional models are foreseen in 2017.

The program will run in parallel with the development of the long coils (4.2 m in US and 7.15 m in CERN) required for the full size magnets.

“The short model program is a fundamental tool to master the design and construction of superconducting magnets, and it is even more important for a novel technology as Nb3Sn” says L. Bottura, leader of the CERN Magnet, Superconductors and Cryostat group. “If needed, we will prolong the short model program to improve our understanding and to reduce the risks in the construction of the prototypes and of the series.”

Tags:

MQXFS

magnets

quarupoles

HiLumi

Recent progress of the HiLumi project

Margarita Synanidi — Mon, 01 Dec 2014 14:37:51 +0000

Key highlights towards the High Luminosity LHC era
by Agnes Szeberenyi (CERN)

LHC/ HL-LHC Plan (last update 24.09.2014)
Image credit: HiLumi

More than 110 experts from all over the world gathered in Tsukuba, Japan for the 4th Joint HiLumi LHC/ LARP Annual Meeting between 17 and 21 November 2014, hosted by the High Energy Accelerator Research Organization (KEK).

The event started off with the plenary sessions where management of the collaboration (Dr. Frederick Bordry for CERN, Prof. Yasuhiro Okada for KEK, Dr. Steve Gourlay for USA) gave invited talks. The first plenary session closed with the High Luminosity LHC status updated by Prof Lucio Rossi, HL-LHC Project Leader. Prof Rossi also officially announced the new HL LHC timeline to the collaborators.

One of the highlights of the plenaries was the status update on the Preliminary Design Report, by Dr. Isabel Bejar, as the main deliverable of the project, which will be published soon as a CERN Yellow Report. 3 days focused on the work package parallel sessions, reviewing the progress in design and R&D not only for the EU funded but also non-EU funded work packages.

Key highlights from the Accelerator Physics and Performance activity (WP2) included a refined optics and layout of the high luminosity insertions, an updated impedance model of the LHC and Hl-LHC, and the need of low impedance collimators was confirmed. One of the main results of the IR Magnets activity (WP3) in the past 18 months was a baseline for the layout of the new interaction region. Engineering design and prototyping of most of the magnets has been started, and first tests of near-to-final equipment are expected next year. The Crab Cavities activity (WP4) in this period delivered and tested all 3 prototype crab cavities (4-rod, RFD and DQW) out of which the international design review carried out in in May in BNL made the downselection to proceed with design of the RFD and DQW. A key milestone, to freeze the cavity designs and interfaces, was also met. Highlights from the wrap up talk of the IR Collimation activity (WP5) include the first lay-out for the IR collimation as well as a solid baselines for the collimation upgrade in the dispersion suppressors of around IR7 and IR2. In addition, simulations have continued for advanced collimation layouts in the matching sections of IR1 and IR5, improving significantly the cleaning of physics debris products downstream around the high-luminosity experiments. The Cold Powering activity (WP6) highlights included the world record current of 20kA at 24K in an electrical transmission line consisting of two 20-metre long MgB2 superconducting cables. Other achievements were a conceptual study and preliminary design of a novel concept of cold powering system (cryostat and current leads) connected to the Superconducting Link, definition of cryogenic requirements and flow schemes. The meeting covered also many progress in the other (non-FP7) WPs, especially for machine protection, cryogenics, vacuum, beam instrumentation, etc. A delicate arbitration among the needs of CC test in SPS-LSS4 (Coldex experiment) and the needs of continuing study and tests for e-cloud mitigation by vacuum people was carried out.

The final FP7 HiLumi LHC / LARP Collaboration Meeting will be held between 26-30 October 2015 at CERN. As a contribution to the UNESCO International Year of Light, special events celebrating this occasion will be organized by HL LHC throughout the year. Stay tuned for the latest updates in the CERN Bulletin and CERN website.

Tags:

From the FP7 HiLumi Design Study towards the High Luminosity LHC

Margarita Synanidi — Mon, 24 Nov 2014 13:50:29 +0000

From the FP7 HiLumi Design Study towards the High Luminosity LHC
by Agnes Szeberenyi (CERN) and Livia Lapadatescu (CERN)

Group picture from the 3rd Joint HiLumi LHC-LARP Annual Meeting 2013.
Image credit: HiLumi LHC.

To mark the approval of the High Luminosity LHC Programme by the CERN Council in June 2013, the 3rd Joint HiLumi LHC-LARP Annual Meeting was held in conjunction with the HL-LHC kick-off.

The event took place at the Daresbury Laboratory in the UK between 11-15 November 2013, with an outstanding attendance of more than 160 scientists from all over the world, including Japan, Russia and the US. Directors of major accelerator laboratories were present as invited prominent speakers.

The first part of the event covered the kick-off of the HL-LHC project, advanced as a first priority for CERN in the years to come. Following the format of the previous annual meetings, the second part of the event focused on the progress in design and R&D of the FP7 HiLumi Design Study. Plenary and work package parallel sessions were organized and focused on the work of the Parameter and Lay-Out Committee, the collaboration with LARP, the achievements and reports from work packages. The outcomes and recommendations of the CERN Review of LHC & Injector Upgrade Plans Workshop (RLIUP) were also reported.

The 4th Joint HiLumi Annual Meeting is planned to take place in November 2014 at KEK, the High Energy Accelerator Research Organization in Japan.

Read more >>

Tags: