JAERI-Conf 95-021

PA22
CONCEPTUAL DESIGN STUDY FOR ALUMINUM RECYCLER RINGVACUUM CHAMBER IN FERMILAB
Hajime ISHIMARUKEK National Laboratory for High Energy Physics
1 -1 Oho, Tsukuba, Ibaraki 305 JAPAN§ 1. INTRODUCTION
The purpose of this study is to propose analuminum chamber with superior performance andcharacteristics.
~·high reliability at low cost for the recycler
ring 1 > in Fermi lab. Key performance advantages ofaluminum chamber and components in comparison tostainlesssteel

stainless steel are provided with the requirements
needed for developing the recycler ring. Analysis
and actual case experience indicates that when
stainless steel components are irradiated by
antiproton beams, melt-down can occurs, but notaluminum as it has a very high tolerance.
It is understood that

Dosl tlon

the antiproton storage

ring has basically noeffect of dynamic outgassing.
However, for high current proton storage ring suchas CERN-lSR had dynamic gas desorption effect.

Fig.2 Temperature distribution irradiated fromlocalized high heat flux against stainless steel

Antiproton ring has negative potential, thenand aluminum ..

ionized ion is trapped within antiproton beam.
§3. VACUUM BEAM CHAMBER§2. BENEFITS OF ALUMlNUM 2 >Extrusion is possible to make elliptical

A. Beam chamberchamber with heater groove as shown in Fig.1.

long. Since the bending angle for half cell isless than I 0 , it is not necessary to provide aCircumference of the ring is about 3,300 m

bending process for bend beam chamber. Extruded
aluminum tube with elliptical aperture and heater
groove are used for bending rnagnet and quadrupole
magnet chambers. Length of the unit beam chamber
is about 1 7 m long. Thickness of the ellipticalchamber is 4 mm. Total number of 17 m long beamchamber is about 200 pieces along the entire ring.
Using automatic welding beam chamber, beam
position monitor and bellows can be joined without
flanges as shown in Fig.3.
Fig. 1 Cross section of beam chamber for bendingand quadrupole magnets.
Clean extruded pipe has very low specificoutgassing rate, Q 0 at 1 50°C, 21~ hours baking 3 >with following performance: Torr flls cm 2
99.99% high purity aluminum: 2 X 1 o- I.
guaranteed high purity aluminum: 10- I 3
without bakout of aluminum: part in I o - l 0
originally proposed stainless steel: I o- I 2
Based on the aluminum vacuum system performance
charactristic,

the major advantages are:I) Reduce pumping speed of ion pumps.
2) Extend distance between ion pumps.
3) Before baking residual gas is mainly water
after· baking residual gas is mainly hydrogen. If
bakeout by chemical process'>

Fig.3 Half cell beam chamber of 17 m long consistsof bellows, beam position monitor joined automaticwelding without flanges.

of COF 2 is employed,a vacuum of I o- 1 0 Torr region can be achieved witha mild bakout 80°C instead of the normal

End of the chamber against gate valve has flange.
The design and construction of bellows for 1 7 m

temperature of 150°C.

long vacuum beam chamber require thermal expansion

4) Energy loss dE/dx is proportional to materialand contraction of about 34 mm for 1 00°C

density,p and atomic number squared of thematerial, z 2 • The localized high heat flux foraluminium was more than several ten of times
higher than stainless steel material against meltdown and the fine leak from the flanges.
Temperature distribution of localized heat flux
irradiated flange is shown in Fig.2 due to lowtemperature rise during baking procedure.
Flanges for the pumping manifold ICF -1 1 4 andthe gauges ICF-70 are adopted on the vacuum
chamber. Gate valve will be used aluminum alloy
products. The distance of the gate valve is about
150 m

energy Joss and high thermal conductivity-85-long.

JAERI-ConfB. Beam chamber material
The high purity 99.99% aluminum should be
used to minimize adsorption and desorption fromthe chamber wall. The high purity aluminum areproduced by gas bubbled flushing of argon andhalogen mixture to reduce the internal hydrogen toless than 0.05 cm 3 /100gr•Al 5 J. A special extrusion
process 2 J using an oxygen and argon mixture withwater content in the I 0 ppm range is used in thechamber to keep the surface clean. Depth profilesof the oxide layer of the EX extruded surface wereanalyzed by Auger electron spectroscopy. It was
found that the oxide layer for the EX extruded
surface was about 30 A thick. On contract, theoxide layer for an ordinary extruded aluminum
surface is I 20-180 A thick.
C. Beam position monitor
Beam position monitors are required for every
quadrupole magnets. Total number of the beam
position monitors are about 200 pieces. Primary
candidate for beam position monitor iselectrostatic pickup type. The cut electrodes
which as elliptical aperture same as beam chamber
are installed in aluminum housing. The electrodes
are made from titanium plate. Assembled electrodeis mounted on aluminum flange using ceramicinsulators. Output signals are fed using nonmagnetic SMA coaxial feedthroughs. The housing
utilize extruded aluminum tube. After installationof electrode inside the housing and calibration
using wire as beam position monitor, the flange
and the housing assembly are welded by electron
beam welder.

95-021

produced by hydraulic forming of a seamless tube
and provides the most uniformed wall thickness
with the longest fatigue life. The thickness ofthe corrugated part of the bellows is 0.3 mm while
the thickness of the welding edge is 4 mm. This
bellows has life time of more than I ,000 cycles
for +5 mm expansion and 35 mm contraction. RFshield is not necessary inside the bellows due tolong beam bunches.
SMA type feedthrough has good RF
characteristics over a frequency range of DC-4
GHz. These coaxial types made of aluminum andceramic brazed are useful for beam position
monitor. The outer shield can be welded using
electron beam welder to aluminum housing.
F. Automatic welding assembly
Automatic welding equipment for an ellipticalchambers were developed for small size, light inweight, easy to handle, and ensures uniform
penetration. This equipment is designed to move
the TIG w<-lding torch along the elliptical crosssection of the vacuum chamber by adopting orbits.
The arc torch is supported by automatic arc
voltage controller with servo mechanism. Guide
orbit of the automatic welder can separate two,and can adopt fixed beam chambers installed inbending and quadrupole magnets. Moving area of
automatic welder is inside of 500 mm in diametercircle.

§4. PUMPING SYSTEM
A. Pumping system
Given the criterion of an average vacuum
I 0- 1 0 Torr range, the distance of lumped ion pumps
D. Clean machining and surface treatmentof 30 {2/s is determined on the assumed value ofBeam chambers, flanges, beam position
the specific outgassing rate Q 0 • Fig. 4 showsmonitors are machined using clean machning system, pressure distribution along the beam chamber
namely EX plasma process. EX plasma process means against three kinds of specific outgassing ofmachining in clean oxygen and argon mixture
chamber and pump distance.
environment with Corona discharge, thus producinga) Staniless steel chamber: Q 0 = 1 o- 1 2 Torr {2/sozone. The Ozone is extremely active with strongem 2 and pump distance: 8.5 m long.
oxydization and cleaning effect. After the surface
This value approximate given in reference I andhas been cleaned, high density non-porous oxide
not acceptable.
layer is formed wiLh extremely low outgassingb) Aluminum chamber: Q 0 = 1 o-t 3 Torr Q/s cm 2 andrate~
pump distance: I 7 m long.
To eliminate additional carbon contamination,
This value is acceptable against requirement:.
ozone treatment 6 J was applied on metal surfaces.
c) Aluminum chamber: Q 0 = 1 o- 1 • Torr (2/s cm 2 andThe surface of aluminum without any treatement
pump distance: 34 m long. This value is expected
were exposed to ozone using dry air including
as a margin.
ozone. No carbon was detected in the sputter
Outgassing rate
10~ ~----,------.-----.------ri
profiled layer using Auger electron spectroscopy.
(a) l.Oe-1 2 Torr-1/s-cmZ(b) l.Oe-13 Torr-l/s-cm2

E. Flange, bellows and feedthroughThe aluminum alloy flange is compatible systemfor .stainless steel CF type flanges. A basic
feature of the system is the use of A2219-T&7 dieforged aluminium alloy. The knife edge is amirror-finished surface, processed by a diamond
tool. A titanium carbide coating is applied to thesurface of the knife edge by ion plating. TiC
treatment on the knife edge provides nearly
perfect protection fron sticking between the knifeedge and the gasket, and against surface
scratches. The machined gasket is A I 050-H24. The
combination system of an aluminum alloy and anordinary stainless steel CF flanges using aluminumgasket and aluminum alloy bolt:s are leak-tightduring thermal cycles.
Aluminum alloy A3004 seamless bellows are{c) l.Oe-14 Torr-Vs-onZ
Pumping speed 30 1/sw"':::>
VlVl~10"1010"" L------L----~~----J---___J______J______ J______J
1015253520
5300

DISTANCE (m)Fig.4- Pressure distribution along the beamchamber.
To reduce a cost, new type controlled powersource for ion pumps which one-tenth in size

86--

JAERI-Conf 95-021
compared to the standard is recommend ed. A Dshaped 1-V charactric tic (fold-back over currentprotection) ion pump power supply 71 was used in
the TRISTAN without any problems.
Roughing pump system are transporta ble cart
station. After starting ion pumps, roughing pumpstation of turbomolec ular pump and dry-pumpcombinatio n will be separated from the metal seal
right angle valve with manual operation. Dry-pumpconsists of diaphragm type and drag pumps
combinatio n. This combinatio n is oil-free pumpsystem. Distance of the roughing pump is about 70
m long. Two roughing pump stations are adopted
inside section with I 50 m separation by gatevalves.
B. Operations
Estimated pumping time will be about several
hours from atmospher ic pressure to operatingpressure of turbomolec ular pump. Upon reaching toI o- 6 Torr range using chemical process at 80°C
instead of ordinary I 50°C baking, sputter ion
pumps operation is activated by a single ON switch
for many of the ion pumps along the storage ring.

§5. PROTOTYP E BEAM CHAMBER FOR EVALUATI ONThe prototype beam chamber is two 17 m longwith elliptical shape joined aluminum alloy
bellows without flanges. Total length is 34 mlong. The unit chamber of 8.5 m long has dummy
beam position monitor, pumping manifold of ICF -I 14and gauge port of ICF-70 flanges as shown inFig.5. Ends of beam chamber are flanges of ICF1 52. These flanges are only use for connect anddisconnect for transporta tion. Two 30 OJs ion
pumps are installed. A 50 fl!s turbomolec ular pumpand dry-pump combinatio n as a roughing pump isinstalled. All-metal seal right angle valve
installed between the beam chamber andturbomolec ular pump. Distance of the ion pumpis 17 m or 34 m long. The expected ultimate
pressure on the ion pump is I o- I 0 Torr range
during the 150°C, 24 hours baking period.
The chemical process using COF 2 , and fast
pump-down process 8 J using super-dry nitrogen will3) lnsta.ll ion pumps at a distance 17 m or 31~ mapart to achive the predicted ultimate pressure ofI o- I 0 Torr range.
Acknowled gements
The author wishes to thank Dr.H.Edwa rd andDr.D.Finle y for their encourage ment's. The authorgreatly appreciate s Dr.P.Limo n, Dr.S.Holm es, Dr.
B.Foster and Dr.G.Jacks on for valuable
discussions . The author greatly acknowled ges
Prof.M.Mis hina for his help.
The author thanks Hitachi Zosen and Sho..;.,aAluminum to discuss about prototype beam chamber
manufactu ring. The author wish to thankMr.F.Koide , SMC Corporatio n for helpful
suggestion s and correction to this Conceptua lDesign Study. Finally, the author acknowled ges
ALVALAB for support.
References
I. Conceptua l design study for recycler ring, MayI 5 ( 1995) Ferimilab
2. 1-!.lshirnaru : J. Vac. Sci. Techno!., A2 (2),(1981f) 1170
3. H.lguchi, T.Mornose and H.lshimaru : J. Vac. Sci.
Techno!., A I I (4), ( 1993) 1708
1~. K.Tatenum a, T.Momose and H.lshimaru : J. Vac.
Sci. Techno!., A I I (4), (I 993) 171 9
5. Y .Kato, T.Kitarnur a, E.lsoyama, M.Hasegaw a,T.Momose, and H.lshimaru : J. Vac. Sci.
Techno!., A6 (6) (1988) 3111
6. T.Momose, Y.Maeda, K.Asano, and 1-f.ishimaru , J.
Vac. Sci. Techno!. Al3 (3), (1995) 515
7. H.Hisamat su, T.Momose, and H.lshimaru : Vacuum
Vol.43, No.8 (I 992) 823
8. M.Miki, K.ltoh, N.Enomoto and 1-!.lshirnaru : J.
Vac. Sci. Techno!., A 12 (4), (1994) 1760

be applied for the test chamber.
§6. KEY RECOMME NDATIONS
1) Construct extruded aluminum beam chambers, each
17 .m long. The unit chamber installed withbellows, beam position monitor, pumping manifold.
2) Using automatic welding, beam chamber, beamposition monitor and bellows can be joined without
flanges.
ICI"152B

ICP70W

JCTlSZB

1 CF 1 l 4 W

30L/S

P and Dry pump

IP

8. Sm
17m

17m

pumpingFig.5 A prototype beam chamber consists of dummy beam position monitors,ports, gauge ports and bellows.

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