1. The Budker Institute of Nuclear Physics
CR arc vacuum chambers

2. CR arc scheme All chambers potentially bake-able
BINP
CR arc scheme
All chambers potentially bake-able
Type
Cross-section internal
Dipole
Supper-ellipse 390x146 S=3.5
or rectangular 380x146
4P+6P
+pump(?)
1. Circular ID150
2. Supper-ellipse 400x180 (dream)
No space for ribs
Pickup vessel
+ corrector
+ pump
1. Circular ID320
2. Circular ID440
or Supper-ellipse 440 x 190
Ribs?
Preference: minimization of wall thickness for fast ramping

3. CR dipole chamber Purpose
BINP
Consideration of options for providing of bake-able CR dipole chamber for UHV application in pressure range 1e-11 mbar or less.
- Decreasing of wall thickness of the chamber to decrease its influence on magnetic field homogeneous during fast ramping (up to 1 T/s).

4. CR dipole chamber requirements
BINP
CR dipole chamber
requirements
Aperture: Beam most extreme coordinates in CR dipoles calculated by I.Koop.
It was agreed that vertical and horizontal coordinates of the chamber walls have to be higher on 7 mm and 20 mm correspondingly in compare to the calculated coordinates. Note that 7mm and 20mm is about 10% of half of vertical and horizontal sizes of the chamber.
Baking temperature: 300°C is recommended to get outgassing rate less than 1e-12 mbar*l/(s*cm^2) for H2 and less than 1e-13 mbar*l/(s*cm^2) for others components. Taking into account possible temperature deviation during bake-out, maximum value of temperature at least 350C has to be used for mechanical calculation.
Maximum stress under atmosphere pressure: 150 Mpa at 350°C for 316LN or alloy.
Antiproton optics (x,y )
RIB optics (x, y)
(62, 65)
(60, 61)
(80, 63)
(96, 58)
(100, 63)
(125, 56)
(115, 62)
(160, 44)
(155, 46)
(165, 40)

5. CR dipole chamber variants
BINP
Thin wall with super-elliptical shape and ribs:
2. Thick wall with rectangular shape and a radii in corners:
Shape with a=190 & b=73 (380x146 – GSI specification) fits requirements for aperture
Gap between chamber and magnet yoke – 4mm (looks small for installation heater and insulations). But if CERN technology…
Shape for a=195 & b=73mm for deferent “S”.
At S=3.5 the shape well fits requirements for aperture.

6. CR dipole chamber super-elliptical
BINP
- Gap for installation of heater (between ribs) and thermo-insulation – 10mm !!!
- Gap between ribs and magnet yoke – 3mm – enough for thermo-insulation (small area).
S=3.5,
distance between ribs – 50mm
Rib’s thickness – 6mm

7. CR dipole chamber Next steps:
BINP
Next steps:
There is draft version of technical specification based on GSI specification for HEBT dipole chambers.

8. CR dipole chamber
BINP
Next steps:

9. CR dipole chamber variants
BINP
CR dipole chamber
variants
Next steps:

10. 1. super- elliptical 2. rectangular CR dipole chamber Production steps
BINP
1. super- elliptical
Incoming material or 316LN sheets 2 & 6 mm
Steps:
Stamping of half parts of profile from 2mm sheet.
- Longitudinal welding of profiles.
Machining of ribs (water jet cutting or laser cutting)
TIG welding of ribs with profile
Machining of the modules ends.
Assembly of the chamber: transvers welding of modules (5 pieces) to each other.
2. rectangular
Incoming material : Given profile made of or 316LN (8 mm).
Steps:
Cutting and machining of module’s ends.
Assembly of the chamber: transvers welding of modules (5 pieces) to each other.
Next steps:
Cleaning in ultrasonic bathes
TIG welding of bellows and CF flanges
Vacuum firing at 950°C
Geometry, magnetic permeability and vacuum tests

11. Pickup combined with corrector and pump
CR 4P + 6P chambers
BINP
Simple circular with ID=150mm everywhere where it is possible. Pump in-between 4P & 6P?
Supper-ellipse 400x190x3 (dream). Pump in-between 4P & 6P?
Pickup combined with corrector and pump
Circular ID=320mm with pump port.
Simple circular ID440mm with pump port or Supper-ellipse 440x190x3 with pump port (corrector design).
Note: Existing of pumping port makes installation (or exchange) of pickup’s strips more convenient.

12. Design conception for short oval chamber with longitudinal ribs
BINP
Example:
oval 420 x 146 (Rsmall=65)
fits requirements for dipole chamber
Horizontal limitation makes wall thickness decreasing from 6mm to 4mm
Design optimization for 4P + 6P chamber
~1200
~600 A
A - A
4P P
400
Pump? A

13. Thank you for your attention