Linear Collider Machine Protection Issues

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15 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

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Linear Collider Machine Protection Issues

M. Palmer

Injection System


Injector


Damping Rings


Bunch Compressor and Transfer Sections

Main LINAC

Beam Delivery System

Questions

Injection System

NLC

TESLA

Injector


???


e
+

undulator located


before IP

Damping Rings


0.8 A @ 1.98 GeV


160 mA @ 5 GeV


Permanent wigglers



Ring protection issues similar to existing rings

Bunch Compressor
and

Transfer Sections


Diagnostics?


Beam dump(s) before


main LINAC


Diagnostic section


Possible

beam dump


before main LINAC

Main NLC LINAC

MAID System


Monitor orbit tolerance


Generate
permit

for DR extraction

Hardware verification required for DR extraction


Klystron/Modulator, Magnets, Movers, Timing, Control System


100
m
s
polling timescale


Specific concern: Possible back
-
phasing of RF sector. Implications?

Pre
-
LINAC beam dumps?


Keep as much of machine active as possible during fault

Pilot Pulse


Require low intensity pulse to avoid damage


I
i
10x,
e
h
h
10x,
e
v
h
1000x


Operative when break in operation of < 1 sec. Detailed ramp to
full intensity

Main TESLA LINAC

TTF methods


Monitor current losses


Inhibit gun (3
-
5
m
s
)


Similar methods may be applied in final design


Orbit tolerance monitoring easily added


Easily applicable at LINAC start

Beam remains in DR on LINAC inhibit

Beam expected to continue thru LINAC on magnet or
module failure

Fast Emergency Extraction Line (FEXL) at end of LINAC


Diverts beam from BDS in 1
-
2 bunches


Inhibits DR extraction within ~200 bunches of problem


Serves as bypass during commissioning

LINAC Bunches & Current Densities

NLC

TESLA

Q
bunch
(nC)

1.2

3.2

N
bunch

190

2820

N
fault

to BDS

190

1
-
2

N
fault

to
LINAC

190

~200

Entrance

Exit

Entrance

Exit

s
x,y
(
m
m)

31, 4.4

7.7, 1.1

320, 16

60, 3

r (
pC
/
m
m
2)

1.4

22

0.10

2.8

Beam Delivery System

NLC

TESLA

Post
-
LINAC
Kickers


Final Focus Kicker



Verifies ramp



Inhibit available 100
m
s



before DR extraction


FEXL can fire within 1
-
2


bunches.

General
Collimation


0.25
-

0.5 X
0

spoilers


20 X
0

downstream absorbers


1 X
0

spoilers


20 X
0

downstream absorbers

Energy Collimation


O(few
m
s
) failure response


c

withstand 190 bunches


Magnetic Energy Spoiler


c

displacement plus
e
v
h

Betatron
Collimation


SLC experience
c

few evts/run

Chromaticity
Collimation


Detector implications of


beam halo hitting CC spoilers

Halo Suppression


Octupole tail folding

Questions

Injector System/Damping Rings


Stability issues for downstream fault


Beam dump between DR and LINAC


Permanent Magnet Wiggler/Undulator protection issues

LINAC


Early LINAC protection scenarios


RF phasing

System Issues


Startup and recovery plans


Alignment


Optics validation


Protection system failure analysis

Collimation Issues


Spoilers


Near miss damage


Replacement/maintenance issues


Material damage limits


Absorber


Energy distribution

Beam Halo Implications for Detectors