118 July 2005“Mini-Review” on CNGS Horns

Introduction by K. Elsener 1

““Mini-Review” - IntroductionMini-Review” - Introduction

Function of focusing horns

“History” of CNGS horns

Milestones and set-backs

Modifications – examples

Installation / Schedule

Comments to this “Mini-Review”

N.B. This presentation is using slides presented by Ans Pardons to the workshop NBI2005, Fermilab 7-11 July 2005

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Introduction by K. Elsener 2

CNGS – function of focusing hornsCNGS – function of focusing horns

150 kA 180 kA

2.7 m

43.5 m

400Gev

6.5 ms

Electrical Pulse Timing

Beam Extraction = double pulse= 2.4x10E13 protons per pulse = 10.5µs (flat top el. pulse)

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Introduction by K. Elsener 3

0.35 m

35 GeV positively charged particles leaving the target

Magnetic Horn : Principle of focusing

inner conductor

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Introduction by K. Elsener 4

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Introduction by K. Elsener 5

Particles traverse inner conductor Particles traverse inner conductor -> it must be thin (e.g. 2 mm)-> it must be thin (e.g. 2 mm)

High current High current -> heating-> heatingBeam pulse (energy depos.) Beam pulse (energy depos.) -> heating-> heating

-> stresses ---> fatigue-> stresses ---> fatigue(1 year < 4 Mio. Pulses)(1 year < 4 Mio. Pulses)

Radiation + HumidityRadiation + Humidity -> corrosion-> corrosion

Building horns is a difficult business …Building horns is a difficult business …

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““History” of CNGS hornsHistory” of CNGS horns

T=24°C T=33°C

Design + fabrication of 2 horns + 1 reflector under responsibility LAL/Orsay - Paris

Some design studies, calculations, …Horn plates & outer conductor readyNon-conformity on location “spider grooves” inner conductor (repair started)Horn assembly startedStriplines & cooling circuit: not started

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MilestonesMilestones & Set-backs & Set-backs

Horn 1 delivered to CERN by LAL/Paris in April 2004

A number of 15+ points have to be corrected to guarantee the reliability (e.g: stirrups, frame, ceramic insulation on water outlets, glass disk, …) -- LAL team reluctant to discuss repairs.

Crisis meetingCERN / LAL 24 July 2004

LAL to concentrate on (a) reflector modifications (b) electric “fast coupling”

Repair, modifications & final assembly of horn taken over by CERN

Stripline + cooling circuit: design, fabrication & tests taken over by CERN

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Modifications - ExamplesModifications - Examples

Ex. 1: Link between outer conductors and drain pipe for cooling water evacuation

Helicoflex SS collar

Ceramic muff withTitanium flanges

TIG Weld (Al 6083)

Tin/Ag seal

SS bellow (316L)

Outer conductor

Drain pipe

Solution

ARCLEX insulators cannot be used in humid areas

Rejec

ted

Received from LAL

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Introduction by K. Elsener 9

Modifications - ExamplesModifications - Examples

Ex. 2: Modifications on the cooling water feed lines (normal + spare line)

Rejecte

d

Received from LAL

(to ceramic insulators) Brazed connection with ceramic

insulators broke (too much strain)

New smooth bellowsto avoid stress in ceramic insulators

Solution

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Horn Assembly - CERNHorn Assembly - CERN(with all modifications)(with all modifications)

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StriplineStripline

10kV

150kA

TRANSFO

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LAL Crisis – cont.LAL Crisis – cont.

24 July 2004:LAL to concentrate on (a) reflector modifications (b) electric “fast coupling”

10 Dec 2004:LAL to concentrate on electric “fast coupling”Reflector modifications takenback to CERN

Several months / many visits to LAL / many discussionsMis-understandings on engineering / production quality ?Non-communication ?

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Glass Disk EnigmaGlass Disk Enigma

Received from LAL

Glass plate broken Problem = conceptual

After modification

Crack discovered ~weeks after electrical tests

SolutionProblem

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CNGS Installation Planning

Horn & Reflector: Oct. 2005Striplines & Cooling: Nov. 2005

Installation / ScheduleInstallation / Schedule

CNGS Commissioning w/beam

Start: 29 May 2006

various scenarios can be imagined

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Introduction by K. Elsener 15

Comments to this “Mini-Review”Comments to this “Mini-Review”

Why hold this “Mini-Review” ?provide an opportunity to discuss possible solutions

Background:2002 – 2004: CNGS had yearly reviews

2005: no review foreseen15 June 2005: there appears to be a design problem

on horns (glass disk)

Goal (ambitious?):reach a consensus on the direction to take / the next steps

Main problems: Manpower / Time (not money)