Beam Windows
for high transverse density beams
By theCERN «Groupe Méthodes»

Presented by L.Bruno
AB/ATB

7-11 November 2003

Targets & Dumps Section

NBI 2003
Presentation by L.Bruno (CERN AB/ATB)

1

Beam Windows

For high transverse density beams

OUTLINE
1. Statement of the problem
2. Standard window systems
3. New developments
4. Window materials
5. Summary

7-11 November 2003

NBI 2003
Presentation by L.Bruno (CERN AB/ATB)

2

The structural problem

Primary static membrane stresses

q=1 bar=0°σc
Thickness t=0.1mm

Solid circular disc fixed and held
under uniformly distributed pressure
7-11 November 2003

NBI 2003
Presentation by L.Bruno (CERN AB/ATB)

Titaniuma = 30 mm(Beam Line)σc = 264 MPa
yc = 1.4 mm
a = 50 mm(Target Unit)
σc = 339 MPa
yc = 2.7 mm
The structural problem
implies large displacements (yc>t/2), which callfor iterative solutions.
3Comparison: Beryllium windows
Primary static membrane stresses

Beryllium
q=1 bar=0°

σc
Thickness Ø 2.5” : t=0.020” (0.508mm)
Ø 4” : t=0.025” (0.635mm)

Solid circular disc fixed and held
under uniformly distributed pressure
7-11 November 2003

NBI 2003
Presentation by L.Bruno (CERN AB/ATB)

Ø 2.5” (a=~32mm)(Beam Line)σc = 166 MPa
yc = 0.37 mm
Ø 4” (a=~51mm)(Target Unit)
σc = 222 MPa
yc = 0.84 mm
The structural problem
implies large displacements (yc>t/2), which callfor iterative solutions.
4Temperature distribution
CNGS beam parameters

Temperature [°C]

800

758°C

Ultimate
intensity

600 544°C

400

Beam sigma = 0.53 mm
Nominal int. = 2.4 1013 p
Ultimate int. = 3.5 1013 p

Temperatures too highNominalintensity

200M.Sans

000.5

11.5r [mm]r [mm]

22.5

The temperature distribution induced by the CNGS beam was evaluated by FLUKA.
Temperatures higher than 50°C are affectedby statistical errors <1%. The simulation
NBI 2003
7-11November
2003
75
covered 3 10 events with a 0.25mm
x by0.1mm
Presentation
L.Brunoaxi-symmetric(CERN AB/ATB) binning.

Comparison: Beryllium windows
CNGS beam parameters

250205°C

Temperature [°C]200

Ultimateintensity

Beam sigma = 0.530 mm
Nominal int. = 2.4 1013 p
Ultimate int. = 3.5 1013 p

150°C

150Nominalintensity

100a=~32mm

SF=0.64 @ 200°C
SF=0.73 @ 300°C

a=~51mm

SF=0.85 @ 200°C
SF=0.97 @ 300°C

50M.Sans

000.5

11.5r [mm]

22.5

3

The temperature distribution induced by the CNGS beam was evaluated by FLUKA.
Temperatures higher than 50°C are affected by statistical errors <1%. The simulation
7 events with a 0.4mm x 0.1mm
NBI 2003
covered3 102003
axi-symmetric binning.
7-11 November
Presentation by L.Bruno (CERN AB/ATB)

6

Temperature distribution
Test case: Beam sigma = 0.795 mm

Temperature [°C]

400372°C

300

Ultimateintensity

Beam sigma = 0.795 mm
Nominal int. = 2.4 1013 p
Ultimate int. = 3.5 1013 p

266°C

200

Nominalintensity

100

a=30mm

SF=0.61 @ 300°C
SF=0.69 @ 400°C

a=50mm

SF=0.78 @ 300°C
SF=0.88 @ 400°C

M.Sans0
00.5

11.5r [mm]22.5

3r [mm]The temperature distribution induced for a test case beam was evaluated by FLUKA.
Temperatures higher than 50°C are affected by statistical errors <1%. The simulation
7 events with a 0.4mm x 0.1mm
NBI 2003
covered3 10
axi-symmetric binning.
7-11November
2003
Presentation by L.Bruno (CERN AB/ATB)

7

Temperature evolution
at the beam spot – Test case500266°C

T [°C]

100

199°C

50

@ t=50ms

10
50.01

Beam sigma
Nominal int.
0.1

= 0.795 mm= 2.4 1013 p
1

10100

1000

t [ms]
Titanium has a relatively low thermal diffusivity of 2.7 mm2/s (as a comparison, graphite
has 75 mm2/s). This value implies a build-up of temperature at the second extraction.
7-11 November 2003NBI 2003
Presentation by L.Bruno (CERN AB/ATB)

8

Brazed Windows(SPS beam obstacles and monitors)“knife”

Brazedjoint“knife”

Flange7-11 November 2003

Air

VacuumWeld

FlangeFoil
NBI 2003
Presentation by L.Bruno (CERN AB/ATB)

9

Captive Windows

Air
Vacuum(nTOF Fast Induction Chamber)

Foil
7-11 November 2003

NBI 2003
Presentation by L.Bruno (CERN AB/ATB)

VacuumsystemHelicoflex
joint

10

Foil
7-11 November 2003

NBI 2003
Presentation by L.Bruno (CERN AB/ATB)

Reinf.

Air

VacuumReinforced Captive Windows

Helicoflex
joint

11Window Materials
Captive reinforced
windows
Ti-γ

800
St.Steel

Cp [J kg-1K-1]

600(Ti45.5Al2Nb2Cr)(@704C-815C)

Ti 99%

Ti-β(Ti15Mo3Nb3Al.2Si)

Ti-α(Inconel 713LC)(Ti6Al2Sn4Zr2Mo)(@ 540C-870C)Co Alloys(Haines 188 @ 540C-870C)

400

Ni Alloys

Captive windows(Nb10W2.5Zr @580C)

Refractory Alloys

200(T111 - Ta8W2Hf )(@540C-870C)

00200

400

(L.Bruno, S.Sgobba)

600800σ y [MPa]
7-11 November 2003

NBI 2003
Presentation by L.Bruno (CERN AB/ATB)

12

Status and Future Activities
1. High specific heat,thermal diffusivity andphysical/chemical stability (e.g. crystal growth,oxidation resistance) are key factors;
2. De-coupling the pressure-bearing from the leaktighness function eases design and lowers costs;
3. Standard iterative analytical design formulas arevery conservative for ductile materials.
4. Thermal stresses, stress waves, fatigue, axial
shocks are to be studied.
5. Tests are planned at CERN under CNGS nominal
beam load.
7-11 November 2003

NBI 2003
Presentation by L.Bruno (CERN AB/ATB)

13