Electron Source Configuration

Axel Brachmann

- SLAC -

Jan. 19 2006, KEK GDE meeting

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at Stanford Linear Accelerator Center

Layout as defined in the Baseline Configuration Document

Positron-style room-temperature

accelerating section

diagnostics section

standard ILC SCRF modules

sub-harmonic bunchers + solenoids

laserE=70-100 MeV

Additional Responsibilities: Injector Damping ring transfer SPIN control (LINAC longitudonal DR vertical)

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Overview

Laser System and (laser) optical transfer see Snowmass ’05

Polarized Gun

Bunching Section

NC pre-accelerator

SC e- Injector LINAC

Basic component count

Length estimates

References:- TESLA TDR- A. Curtoni, M. Jablonka; Study of the TESLA preaccelerator for the polarized beam, TESLA-2001-20

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BPM

Load-lock chamber connects here

Ion Pump RGA

High voltage insulator

e- beamlaser beam

Magnetic lens

120 kV DC Gun – Baseline Design is SLC Gun

Approximate locationof cathode

Leak valve

Load-lock andcesiator

on other side

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Loadlock System for Cathode Preparation and Installation

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ILC DC Gun Design

SLC gun is baseline

• 120 kV, 1.7 MV/m at Cathode• Possible higher gradient, eg. at Cornell, Jefferson Lab, Nagoya• New electrode materials, cesiation schemes

Polarized RF gun R&D

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Bunching Section

SHB• Normal conducting sub-harmonic bunching section• Focusing by solenoidal field• Scaling from TTF results in following parameters :

• Distance between sub-harmonic buncher cavities: 200 cm• Bunch compression: 97o rms at entrance to second SHB cavity, and 30o rms at

buncher entrance • Distance to buncher: 38 cm

Buncher• 2 cavities (5 cell) separated by λ/2 (115.3 mm); =1 Structure• 14.8 MV/m (simulations with 12 MV/m)• 12 MeV beam energy after bunching

Cavity # F [MHz] Voltage [kV] Rs [M] Q0 P [W]

1 108 (1/12) 40 8.8 3.4*104 220

2 433 (1/3) 44 4.4 1.7*104 360

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NC Pre-Accelerator

• Energy from 12 MeV ~ 70 - 100 MeV• Positron style room temperature accelerating section• 17 cell cavities, one pair 31 MeV energy gain using 10 MW

klystron• Number of pairs must be selected

– 2 pairs ~ 76 MeV, 0.28 mm.mrad (un. Emitt.)

– 3 pairs ~ 100 MeV, 0.2 mm.mrad (un. Emitt.)

• 1 triplet between pairs• 2 triplets to match to SC LINAC module• Spectrometer arm for independent tuning

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500 MeV SC LINAC and 5 GeV e- Injector LINAC

STEP 1

• Add ~ 424 MeV

• Two standard SC LINAC modules of 12 cavities each

• Gradient: Eacc = 17.8 MV/m

• Lower energy requires doublets instead of triplets

STEP 2

• Energy gain to 5 GeV by 18 standard cryomodules

• Gradient: Eacc = 20 MV/m

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Instrumentation Special diagnostics:

• Gun diagnostics

• Vacuum

• Dark current

• QE diagnostics

Integrated into gun design

• Faraday cup

• Mott polarimeter

BPM’s, Toroids, Wirescanners/Laserwires, Profile Monitors

Bunch length measurements (Marc Ross proposals):

• Band pass mirco wave detectors

• Beam phasing

• Energy / time correclations

Common instrumentation requirements with e+

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Layout and Length Estimates

Component Distance [m]

Pre-Gun Systems

(Laser, OTR, Local Injector Controls)

~ 50

Guns and Load-Lock Installation ~ 5

Y extension lines (with diagnostics and solenoidal field) ~ 3

SHB 1 (solenoidal field) ~ 3

SHB 2 (solenoidal field) ~ 3

Buncher ~ 2.5

Pre-accelerator (to 500 MeV, 17.8 MV/m) ~ 30

RT – SC beamline ~ 12

Injector Linac (to 5 GeV; 18 17 m SC modules 20 MV/m) ~ 306

e- injector to DR transfer line with SPIN rotator ~25

Total Length of Injector Area 439

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Components (e- and e+ source)Components Count

Laser systems 2

Guns 2

‘Y’ bend magnet 1

Solenoidal focusing magnets 9 m

Dipols Diagnostic arm 1

DR transfer 1

Doublets Injection LINAC 2

Triplets Between NC pre-accelerator sections 1

Between NC and SC 2

Total 3

Klystrons (10MW) Buncher 1

Pre-accelerator 1

Injection LINAC 6

Total 8

Cryomodules Pre-accelerator 2

Injection LINAC 17

Total 19

SPIN Rotator DR In/out 2

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