SOR

ports

tocharacteristi cs of TRISTAN Accumulation Ring (TAR)
T, MOI'IOSE
forLaboratoryNationalHigh

Energychambers,

Ceramic

be !lows,windows,

andtheimprove

Physics

1-1 Oho, Tsukuba-shi, Ibaraki-ken, 305 Japan
DesignAbstract

Beam intensity ;n TAR is limited as 40 rnA at b.)
GeV. Instead, 'iO rnA at 8 GeV is expected in future
physics. The corresponding power density is 5.3 KW/m.
Longer beam. I ifetime is also required. Taking into
account the two conditions and troubles in the past,redesign of ceramic chambers, bellows, windows and SOR
ports are carried out. Wider horizontal aperture,kovar soldering, and absobers are equipped In ceramicchambers using SUS-Cu--Al clad material. Rf shield,

Ceramic chambers---··-~~--~--

Beam current is 1 imi ted as 8 GeV, 20 rnA, because
ceramic chambers had troubles at the soldering part
between short aluminum bellows and a ceramic rod. The
soldering part is protected against radiation bymaking shadow (~320 mm) with an absorber. Originally,
the absorbers are made of AI and their axial length is5 mm. The length is not enough to shield radiation
after the beam energy was increased higher than 6. 5

Si0 2 coating, and absorbers are provided for bellows.
Mask assembly is isolated from the window assembly.
Pumping capacity and gap for SOR extraction are increased in SOR ports.
.,....

introduction
As LEP and SLC were begun to operate,"futu re TRISTAN
at KEK" has been discussed in various fields. In any
cases, longer beam lifetime and higher beam current ofTAR are required. TAR has. been opera ted more than byears. Including the_ period of TAR design, about 10years have passed as the TRISTAN era. Much experienceon the TAR vacuum system has been stored during the !0years. Therefore redesign of TAR considering the tworequirements is the best opportunity. To realize
higherbeam current,the/10limiting//

AI:cCui

1-<.9Izw....JI

condition on theljII

times higher than the present limit, 6.5 GeV,
SOR mode. Corresponding SOR power is 2.1
at'rnA
40
Kw/m. Therefore the power of 5.3 KW/m is taken intoaccount for the redesign of ceramic chambers, bellows,windows,

andforisI,'II/I•,' : I ,',','III/,(/:,'IIIt,':'Pb:,',','I/
Il~'l ~..,,:V,~/,',t ,'10/I: ,//1 ~4t'beamI

ellipticalis requested from various fields, installation of more
pumps is necessary.

II'

I ·~:~ ,'I/

I-3

where theircrossection,is tochangeRelatedmm).
changed(48aperture is notThe
extraction.
SORforchambersB
enlarge the gap inlifetimebeamlonger
Asbefore.
asDIP
main pump isch~mbers

II

8 GeV, 50mA beam is expected in future physics forTAR. Equivalent beam current is 6.5 GeV, 100 rnA which

improvement

/,'I/

I

Requirements

AnI

I

I
/1
I I Ifports.

/

I

ceramic chambers must be removed. Redesigned ceramic
areports
and SORwindows,
bellows,chambers,
experience~
theaccountintotaking
describedSORI
I

are 2.5....

/,'I,'II

10102

ENERGY( keY)
Fig.

~124-Attenuation length of Al,
function of photon energy.

Cu,and Pb asatransverse

addition,

lmm

which

bring

about
theofefJdtheatpartsolderingtheon

radiation

results

aboutmm30

Inchambers.

misalignment
about

lengthshadow

shortThe

can not makeceramic

theofsomeon

shadow

Al~S. Smm).

4mm,!0 mm whichisthe absorbers

height ofenoughmateria I (Cu~cladusing

ones

the absorbers are changed to newSome ofGeV(Fig. I).

beam axis,

theThe

mm.

'50

outer

andmm

45

is

length

inner

From

length.

in horizontal

95 mm

the present crossection

is applied as;

Improvementouter

length is made wid.e more 5 mm to obtain enough shadowonmechanicaltheimprove

ceramic-kovar

tochanged

issoldering

AlToceramics.

ofend

thestrength,soldering. Therefore kovar is connected to Al chambers
transition material.

SUS-i\1using.absorbers(5 mm thick x

B chambers, Al
10 mm high)\0 mm wide x

to be usedgoingrods,

toaroundtheis toDifferencein our design.

bycooled down

arewater.

Fig.3. The

mm

Assuming

long.

13 mm.

expansion is
8at

50

GeV,

isassemblyThe

longest chamber unit fortorisetemperature

shown

inSOR port is 4200
be130

C,

Simplified calculation shows thattemperature rise at Cu(absorber)ceramic

setareishightemperature5

put the absorbers in the bellows itself. The absorbers

absorbersmonitorareHowever,mm is not so effective at 8 GeV. Cu-Al clad material

to obtain

the end ofAt

transition material.

inIn the present TAR, closethe end of the Q or

to the bellows atsame

uniform

becanpressure

circumference distribution.

length,are set close to ceramic chambers by using SUS-Cu-i\1

thermometers

contacting

crossection,

ThetheTMR. By adoptng the ellipticalrequirement as that of

Further,length and shadow

radiation

enoughisshieldshield.

withbel lows

newtherf

insertingsuppressed byapplied onwelded as radiation shielding for bellows.

ceramic chambers.

isbecanfieldrnA

is about 55 C in 5 mm
investigation

Experimental

using electron beam must be done.

28

rise.

WindowsandBeam injection and extraction windows are made ofabsorbers is shown in Fig.2. Attention is also paid tovacuum tight beryllium(Be) plates(0.3 mm thick xlO mm

assembly

Designedthe1tthese ceramic chambers.

a 1 ignment ofrod

cerammic

must

behigh x 20 mm wide forAlandCu

alloys.

high

Heating accelerates

thetendency and sometimes makes

past

that

mentionedin Al-Cu

crackmaterial.

clad

theofcombination

changing

overcomebecanThisboundary. 11

makeeasily

canby

More

attention is paid on using SUS bellows in view of SOR
and onradiation and gas desorbtion,
isriseestimated

C.

90

are

vacuumleak

blowing,

and torque failure.

estimated

toimpurities(H 2 0,beQ.,)radiation
inraceshieldrf

appliedisradiation damage will
alreadyoncoatingmicrons)

done

Ceramics

Kovar~]
ss~

TMR. 2 'w+--Bellows~~(Ti - - -inTAR.

theoutsidesurface.

instability

ThebySORisgas.

dueThisis

towaket1

1r

Thereforebe supressed by applyng Si0 2 (3lD

45 -+--55

IT01Fig.

presentin

accelerated

11of 150 mm are used. No radiation damage protection andnoBe,

The corrosion

helium~!r-type bellows

trackdamage

flowing

theofSimulation

Be !lows
In arc sect ion of TAR,

corrosion

toin

shielded by a molibdenum mask just in front of the Bewindow. The mask system (Mo) is about 1.3 kg and isprecisely.

risetemperature

theevaluate

asformechanicalisTroubles

extraction).

mm widedue

10 mm

I mm thic.k x

injection,

23

electron beam radiation can be used

experiment using
tomaterial(absorbers).

transitioin

theinsteps

toTemperature

instability duex(bsorbor

2 Ceramic-kovar soldering and an absorber using

Fig.

Bellows

withabsorbers.

SUS-Cu-Al clad material.

-125-

rf

insert,Si0 2

coating,andattached to the window assembly. This makes access of
the windows difficult. The window a~sembly and mask
system should be isolated. The mask can be attached tothe Q chamber just in front of the window. The
fabrication technique of the window is electron beam
as before. Welding shape can be circularwelding

insteadrectangular.

ofThe

has

lattertechnicallyConcluding remarks
Ceramic chambers limiting the beam intensity of TAR
bellows, beam windows, and SOR ports are redesigned so
as to be durable against radiation about 5.3 KW/m. The
power density is more than 3 times of the present TAR
Rough calculation satisfies requirements,operation.

hard and is high cost. Heat loading on the Be window

however,is basically the same as in the present.

indispensable.

SOR portsdue

SOR ports are now used at NEI, NE5, NE7, and NE9.
Monitoring ports are an x-ray window for electron beamincrease is not considered here. Further investigationis needed to complete this design.

reasonable
toradiation.

One TSPand onemagnetthegapincludingthechamber

pure

aluminum

thickness is less than 20 mm (Fig.4).
Attention

must

bepaidtocapacity,

isestimated.

Influence

andrisetemperaturedoseradiation

Acknowledgement
The author wishes to thank Mr.

11. Tsuchiya(!HI)

for his calculation of loci in SOR ports.

theIP are attached tooutside of a B magnet chamber. Extracting gap for theport is 20 mm at the downstream, however, at thesextupolerisetemperaturetheismeasurements

coolingchanging

Withoutand a mirror port for e+ and e- beams. As the increaseof SOR studies will be expected, 24 SOR ports will bebutinstalled. Extracting angle is not changed,
pumping capacity at the downstream of the port will be
the desorption due toincreased to compensate

withconfirmation

References
Iizuka,T.

I)

Private communication.

chemicalAsahi

industry Co., Ltd.
2) T. Momose, and H. Jshimaru, J. Vac. Soc. Japan,

the~1.

1989,72.

chamber,
fixed point of the chamber, and assembling
and alignment of the longest unit chamber.

~~-Sx-u~n~._~_-··-_--_--_---_--_-------~-------~~nr': """'s""'r~---;rT[JrDIP

8·--·-::;}

f·----·' l2..

:_ -.. -.------------------I-m •Q & B••••!

JOININGFig.

4

Crossection

of

SOR

arrangement of pumps.

SX

B

-126-

extracting

portand