Beam Windows f or high t ransverse densit y beams By t he CERN - PowerPoint PPT Presentation

Beam Windows f or high t ransverse densit y beams By t he CERN «Groupe Méthodes» L. Bruno Present ed by Targets & Dumps Section AB/ ATB NBI 2003 7-11 November 2003 1 Present at ion by L.Bruno (CERN AB/ ATB)

Beam Windows For high t ransverse densit y beams OUTLI NE 1. Statement of the problem 2. Standard window systems 3. New developments 4. Window materials 5. Summary NBI 2003 7-11 November 2003 2 Present at ion by L.Bruno (CERN AB/ ATB)

The structural problem Primary st at ic membrane st resses Titanium q=1 bar a = 30 mm (Beam Line) σ c = 264 MPa y c = 1. 4 mm = 0 ° a = 50 mm (Target Unit ) σ c σ c = 339 MPa y c = 2. 7 mm Thickness t=0. 1mm The structural problem Solid circular disc f ixed and held implies large displace- under unif ormly dist ribut ed pressure ments (y c >t/ 2), which call f or iterative solutions. NBI 2003 7-11 November 2003 3 Present at ion by L.Bruno (CERN AB/ ATB)

Comparison: Beryllium windows Primary st at ic membrane st resses Beryllium q=1 bar Ø 2. 5” (a=~32mm) (Beam Line) σ c = 166 MPa y c = 0. 37 mm = 0 ° Ø 4” (a=~51mm) (Target Unit ) σ c σ c = 222 MPa y c = 0. 84 mm Thickness Ø 2. 5”: t=0. 020” (0.508mm) Ø 4” : t=0. 025” (0.635mm) The structural problem Solid circular disc f ixed and held implies large displace- under unif ormly dist ribut ed pressure ments (y c >t/ 2), which call f or iterative solutions. NBI 2003 7-11 November 2003 4 Present at ion by L.Bruno (CERN AB/ ATB)

Temperature distribution CNGS beam paramet ers 800 758 ° C Beam sigma = 0.53 mm = 2.4 10 13 p Ultimate Nominal int . 600 544 ° C = 3.5 10 13 p Temperature [° C] intensity Ult imat e int . Temperatures too high 400 Nominal intensity 200 M. Sans 0 0 0. 5 1 1. 5 2 2. 5 r [mm] r [mm] The temperature distribution induced by the CNGS beam was evaluated by FLUKA. Temperatures higher than 50 ° C are af f ected by statistical errors <1%. The simulation NBI 2003 covered 3 10 7 events with a 0. 25mm x 0. 1mm axi- symmetric binning. 7-11 November 2003 5 Present at ion by L.Bruno (CERN AB/ ATB)

Comparison: Beryllium windows CNGS beam paramet ers 250 205 ° C Ultimate Beam sigma = 0.530 mm intensity = 2.4 10 13 p 200 Nominal int . Temperature [° C] = 3.5 10 13 p Ult imat e int . 150 ° C 150 SF = 0.64 @ 200 ° C a =~ 32mm SF = 0.73 @ 300 ° C Nominal 100 intensity SF = 0.85 @ 200 ° C a =~ 51mm SF = 0.97 @ 300 ° C 50 M. Sans 0 0 0. 5 1 1. 5 2 2. 5 3 r [mm] The temperature distribution induced by the CNGS beam was evaluated by FLUKA. Temperatures higher than 50 ° C are af f ected by statistical errors <1%. The simulation covered 3 10 7 events with a 0. 4mm x 0. 1mm axi- symmetric binning. NBI 2003 7-11 November 2003 6 Present at ion by L.Bruno (CERN AB/ ATB)

Temperature distribution Test case: Beam sigma = 0.795 mm 400 372 ° C Ultimate Beam sigma = 0.795 mm intensity = 2.4 10 13 p Nominal int . 300 Temperature [° C] 266 ° C = 3.5 10 13 p Ult imat e int . SF = 0.61 @ 300 ° C a = 30mm 200 SF = 0.69 @ 400 ° C Nominal intensity SF = 0.78 @ 300 ° C a = 50mm SF = 0.88 @ 400 ° C 100 M. Sans 0 0 0. 5 1 1. 5 2 2. 5 3 r [mm] r [mm] The temperature distribution induced f or a test case beam was evaluated by FLUKA. Temperatures higher than 50 ° C are af f ected by statistical errors <1%. The simulation covered 3 10 7 events with a 0. 4mm x 0. 1mm axi- symmetric binning. NBI 2003 7-11 November 2003 7 Present at ion by L.Bruno (CERN AB/ ATB)

Temperature evolution at t he beam spot – Test case 500 266 ° C 100 199 ° C 50 T [ ° C] @ t =50ms 10 5 Beam sigma = 0.795 mm = 2.4 10 13 p Nominal int . 0.01 0.1 1 10 100 1000 t [ms] 2 / s (as a comparison, graphite Titanium has a relatively low thermal dif f usivity of 2. 7 mm has 75 mm 2 / s). This value implies a build- up of temperature at the second extraction. NBI 2003 7-11 November 2003 8 Present at ion by L.Bruno (CERN AB/ ATB)

Brazed Windows (SPS beam obst acles and monit ors) Brazed “knif e” joint “knif e” Weld Air Vacuum Flange Flange Foil NBI 2003 7-11 November 2003 9 Present at ion by L.Bruno (CERN AB/ ATB)

Captive Windows (nTOF Fast I nduct ion Chamber) Vacuum Vacuum Air system Helicof lex j oint Foil NBI 2003 7-11 November 2003 10 Present at ion by L.Bruno (CERN AB/ ATB)

Reinf orced Captive Windows Vacuum Reinf . Air Helicof lex j oint Foil NBI 2003 7-11 November 2003 11 Present at ion by L.Bruno (CERN AB/ ATB)

Window Materials Captive reinf orced 800 windows Ti- γ St . St eel (Ti45.5Al2Nb2Cr ) (@704C-815C ) Ti- β 600 ( Ti15Mo3Nb3Al.2Si) Ti 99% C p [J kg -1 K -1 ] Ni Alloys Ti- α Co Alloys ( I nconel 713LC) ( Haines 188 @ 540C-870C) ( Ti6Al2Sn4Zr 2Mo) 400 (@ 540C-870C) Captive windows (Nb10W2.5Zr @580C) Ref ract ory Alloys 200 (T111 - Ta8W2Hf ) (@540C-870C) (L.Bruno, S.Sgobba) 0 0 200 400 600 800 σ y [MPa] NBI 2003 7-11 November 2003 12 Present at ion by L.Bruno (CERN AB/ ATB)

Status and Future Activities 1. High specif ic heat, thermal dif f usivity and physical/ chemical stability (e. g. crystal growth, oxidation resistance) are key f actors; 2. De- coupling the pressure- bearing f rom the leak- tighness f unction eases design and lowers costs; 3. Standard iterative analytical design f ormulas are very conservative f or ductile materials. 4. Thermal stresses, stress waves, f atigue, axial shocks are to be studied. 5. Tests are planned at CERN under CNGS nominal beam load. NBI 2003 7-11 November 2003 13 Present at ion by L.Bruno (CERN AB/ ATB)