Electron Source Configuration Axel Brachmann - SLAC - Jan. 19 2006, KEK GDE meeting International...

Electron Source Configuration

Axel Brachmann

- SLAC -

Jan. 19 2006, KEK GDE meeting

International Linear Collider

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)

International Linear Collider

at Stanford Linear Accelerator Center

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

International Linear Collider

at Stanford Linear Accelerator Center

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

International Linear Collider

at Stanford Linear Accelerator Center

Loadlock System for Cathode Preparation and Installation

International Linear Collider

at Stanford Linear Accelerator Center

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

International Linear Collider

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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

International Linear Collider

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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

International Linear Collider

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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

International Linear Collider

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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+

International Linear Collider

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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

International Linear Collider

at Stanford Linear Accelerator Center

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

International Linear Collider

at Stanford Linear Accelerator Center