Consumable Collimator R&D - Technical Update

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15 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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Consumable Collimator R&D
-

T
e
c
h
n
i
c
a
l

Update


p
resented
@

B
-
D
meeting

7/27/99

revis
ed 8/12/99


Summary:

1.

Review t
echnical
s
pecifications

(current 8/12)

2.

Review three concepts


tape,

rotor, bar



ad
vanced since Lehman review

3.

Heat dissipation considered


radiation heat transfer sufficient

4.

Bar devic
e requires too much space
, no longer being considered

5.

Design approach: BPMs to position

vac
uum

chamber
(movers); fix
location
center of aperture
relative to BPMs; control dimension of aperture.

6.

No
te: this presentation
was
based on

ZDR collimation
geometry

as a starting point
;
details have
evolved and continue to do so.


Specifications


Beam energy








750 GeV

Beam size (

x,

y)







4
0

m
,
5


m

Beam

max
nominal
offset from axis

(x,y)



?

E
rrant
b
eam, max excursion

(x,y)




?

Particles in

halo
(
per train)





10
9

% of be
am intercepted per side
(continuous)


.
0
5%

Image current heating






~2W


Aperture









2
00
-

1000

m

Edge placement accuracy





10



2
0

m

Edge stability








10


20

m

Length at min gap







.25 r.l.

nu
mber of hits before replaceme
nt




1000

replacement interval






1 year


radiation (self
-
generated)






10
5



10
6

r/hr


beam pipe

i.d. x o.d.






1.0

cm x 1.2 cm

vacuum









<
10
-
7

Torr


General comments


1.

Geometry for Ti per ZDR



2.

Beam halo power absorbed ~0.2 W


-

ZDR power/10 due to reduced particles intercepted.



3.

Image current power ~.5
W


-

a
daptation of Tor’s paper.

-

beam offset from surface is 70

m, implying aperture << 1mm

Tape device


1.

Tape slid
es over radiall
y moveable jaw


-

curved tape
(
per
ZDR
j
aw cross section
)
prevents severing of tape

-

a
xial relie
f slot protects jaw from beam

-

l
ateral relief slot gives clearance for
damaged tape



2.

Beam tube

essentially disappears
@

aperture

(rectangular tube?)



3.

Xferr
ing
2W
(conservative)
heat from tape to

jaw (externally cooled):


-

assume co
ntact resistance is high


radiat
ion between infinite || plates

-

assume tape

at uniform temp

-

assume jaw at ambient
temp 20
o
C

-

result: 283
o
C for tape

Rotary

device


1.

Cross section per ZDR


when revolved about axis of rotor it becomes a
toroid with conic ramp sections.



2.


S
quare section beam tube and articulated ramp (could be thin & flexible).


-

f
lared beam tub
e

moves discontinuity (clea
rance for rotor) away from beam



3.

Removing 2W of heat from the rotor:


-

assume

radiation heat transfer to surroundings at 20
o
C

-

assume rotor at uniform temp

-


r
esult:

rotor temp ~23
o
C



Bar device


1.

Assume 1m useable collimation surface


-

b
ar
length
> 1m

for same usea
ble surface as .32m diameter rotor

-

vacuum chamber
must be > 2m wide (or high for vert
ical

collimation)

-

bar
s

will
bow

due to errant beam hits


Position
ing Collimation Surfaces



1.

Align vac
uum

chamber to beam


-

BPM



chamber on movers



2.

Internal stops for collimation surfaces


-

c
ontrol aperture

directly

-

mechanism
reference
d

to beam tube
,

which is
aligned to beam

-

isolate from chamber distortion

-

measure aperture
?

… capacitance?