High Brightness Injector Development and ERL Planning at Cornell - - PowerPoint PPT Presentation

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High Brightness Injector Development and ERL Planning at Cornell - - PowerPoint PPT Presentation

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High Brightness Injector Development and ERL Planning at Cornell Charlie Sinclair Cornell University Laboratory for Elementary-Particle Physics Background During 2000-2001, Cornell, with much help from JLab, prepared an NSF proposal to

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SLIDE 1

High Brightness Injector Development and ERL Planning at Cornell

Charlie Sinclair Cornell University Laboratory for Elementary-Particle Physics

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SLIDE 2

June 22, 2006 JLab CASA Seminar 2

Background

  • During 2000-2001, Cornell, with much help from

JLab, prepared an NSF proposal to build a 100 MeV ERL to resolve technical issues prior to proposing an ERL-based hard X-ray light source

  • In February 2005, the NSF funded Cornell to

build the injector portion of the original proposal

  • Construction of a fully coherent hard X-ray

source is on NSF’s long range MRE plan

  • In 2006, New York funded Cornell for studies

and work related to completing the proposal for the full light source

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SLIDE 3

June 22, 2006 JLab CASA Seminar 3

Proposal vs. funded

Gun, buncher, and SRF accelerator Merger, precision diagnostics, and dump Main linac Recirculation loop

Two stages – Operate gun and diagnostics in gun laboratory, then operate complete injector (5 to 15 MeV) in the L0 area of Wilson Lab

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SLIDE 4

June 22, 2006 JLab CASA Seminar 4

Injector Specifications

  • Average current – 100 mA

(77 pC/ bunch, 1300 MHz repetition rate)

  • Variable final energy – 5 to 15 MeV
  • Beam power – 575 kW average
  • Bunch length – < 2 ps, rms
  • Transverse emittances – < 0.1 μm-rad

(normalized, rms)

  • Photocathode operational lifetime – 100 hours
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SLIDE 5

June 22, 2006 JLab CASA Seminar 5

Injector Optimization

We developed a genetic algorithm based computational

  • ptimization of our injector, which showed that we

should be able to make very small emittance beams.

(Bazarov et al., Phys. Rev. ST-AB 034202 (2005))

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SLIDE 6

June 22, 2006 JLab CASA Seminar 6

Injector Optimization

  • Optimum transverse emittance is dominated by

the cathode thermal emittance – this is a tremendous advantage for NEA photocathodes, and implies emittance reduction with cathode cooling

  • Emittance compensation works just fine for the

DC gun case

  • Gentle (adiabatic?) bunching is preferred
  • Solutions are insensitive to small parameter

variations

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SLIDE 7

June 22, 2006 JLab CASA Seminar 7

Injector Elements

  • Photoemission electron gun, 750 kV maximum

cathode potential, NEA GaAs or GaAsP cathode, 1300 MHz laser system

  • Normal conducting single cell 1300 MHz

buncher

  • Cryomodule with five 2-cell SRF cavities
  • Precision controlled high power RF systems
  • Merger magnet system
  • Precision diagnostic beam line
  • Full power beam dump
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SLIDE 8

June 22, 2006 JLab CASA Seminar 8

750 Photoemission Gun This gun design incorporates a number of novel features, such as a resistive coated ceramic, photocathode cooling, a cooled beryllium anode, and over 20 m3/sec

  • f hydrogen pumping speed

Beam Out Cathode Entry

The gun was assembled without touching any cathode electrode surface

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SLIDE 9

June 22, 2006 JLab CASA Seminar 9

Gun Ceramic from CPI

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SLIDE 10

June 22, 2006 JLab CASA Seminar 10

Cathode Electrode Assembly

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SLIDE 11

June 22, 2006 JLab CASA Seminar 11

SF6 Tank Installation

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SLIDE 12

June 22, 2006 JLab CASA Seminar 12

Photocathode Load Lock and Preparation System

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SLIDE 13

June 22, 2006 JLab CASA Seminar 13

300 kV, 100 mA Power Supply

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SLIDE 14

June 22, 2006 JLab CASA Seminar 14

Gun and Power Supply in Tank

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SLIDE 15

June 22, 2006 JLab CASA Seminar 15

Beam Line looking toward Gun

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SLIDE 16

June 22, 2006 JLab CASA Seminar 16

Beam Dump during assembly

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SLIDE 17

June 22, 2006 JLab CASA Seminar 17

Starting the shielding

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SLIDE 18

June 22, 2006 JLab CASA Seminar 18

Lasers

  • With our CW argon ion laser, the present setup

will allow us to study

– Photocathode thermal emittance – Photocathode operational lifetime at high average current

  • Adding a laser with RF time structure and

additional diagnostics, we will study

– Emittance as a function of bunch charge – Temporal structure of the bunches

  • 50 MHz, and 1300 MHz frequency doubled Yb

fiber lasers in development with A&EP

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SLIDE 19

June 22, 2006 JLab CASA Seminar 19

Laser Development

  • 50 MHz fundamental frequency mode-locked

Yb fiber oscillator

  • Harmonic mode-locking to reach 1300 MHz
  • Yb fiber amplifier(s) to reach ~ 130 W in the IR.

(100 nj/pulse)

  • Frequency multiplication in LBO to give > 20 W

in the green after pulse shaping

  • Initial transverse shaping with aspherics,

temporal shaping with pulse stacking

  • Pattern control with BBO Pockels cell
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SLIDE 20

June 22, 2006 JLab CASA Seminar 20 30 25 20 15 10 5 Output Power (W) 800 600 400 200 Input Power (mW) 20 15 10 5 Output power [W] 30 25 20 15 10 5 Pump power [W] Slope efficiency 85% 4.4 4.0 3.6 3.2 Output power [Watts] 50 40 30 20 10 Input power [mW] 8 6 4 2 Output [watts] 20 15 10 5 Pump power [watts] Slope efficiency = 78%

First measurements On amplifier Simulation with Liekki Application designer

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SLIDE 21

June 22, 2006 JLab CASA Seminar 21

1.20 0.80 0.40 0.00 Diameter [mm] 800 700 600 500 Distance [mm] M2 = 1.87 0.6 0.4 0.2 0.0 SHG [watts] 5 4 3 2 1 Pump [watts]

15 mm LBO doubler Non-critical phase matched 5 cm focal length

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SLIDE 22

June 22, 2006 JLab CASA Seminar 22

Plan View – Gun Test Lab

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SLIDE 23

June 22, 2006 JLab CASA Seminar 23

Additional Activities

  • Outgassing studies

– Best result to date, following VIRGO prescription, is an outgassing rate of ~ 2 x 10-13 torr-liter/sec-cm2

  • Photocathode preparation

– Routinely prepare ~ 17% QE photocathodes on both GaAs and GaAsP wafers

  • Field emission reduction

– Evaluated 316 LN, Ti4V6Al, and GCIB treated materials – Have achieved “zero” emission up to 20-22 MV/m

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SLIDE 24

June 22, 2006 JLab CASA Seminar 24

Bare Ti4V6Al Electrode

Ti4V6Al Electrode

  • 500

500 1000 1500 2000 2500 3000 3500 5 10 15 20 25 Electric Field (MV/m) Current (pA)

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SLIDE 25

June 22, 2006 JLab CASA Seminar 25

GCIB treated 304 SS

GCIB treated 304 SS

  • 50

50 100 150 200 250 300 350 400 450 5 10 15 20 25 30 Electric Field (MV/m) Current (pA)

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SLIDE 26

June 22, 2006 JLab CASA Seminar 26

Ion Back Bombardment

  • A very bright undergrad student has been

modeling ion creation and back bombardment in the gun

  • We have been using sputtering of cesium

fluoride as a surrogate for what is degrading the cathode quantum efficiency under ion bombarment

  • I can almost explain the QE degradation as due

solely to sputtering of the NEA activation layer

  • We have detailed predictions we can test with
  • ur gun
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SLIDE 27

June 22, 2006 JLab CASA Seminar 27

Current Status

  • Gun, preparation system, beam line, and dump

are all assembled and baked

  • We have been plagued by a series of leaks ion

the preparation system, and most recently, in the gun

  • We see strong field emission at relatively low

voltages on the gun, and so far, have not been able to process through this

  • I am starting to survey the local bridges
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SLIDE 28

June 22, 2006 JLab CASA Seminar 28

SRF Cavity Design

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SLIDE 29

June 22, 2006 JLab CASA Seminar 29

First 2-cell Niobium Cavity Weldment

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SLIDE 30

June 22, 2006 JLab CASA Seminar 30

First Vertical Test

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SLIDE 31

June 22, 2006 JLab CASA Seminar 31

RF Power Coupler Design

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SLIDE 32

June 22, 2006 JLab CASA Seminar 32

RF Power Coupler

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SLIDE 33

June 22, 2006 JLab CASA Seminar 33

HOM Loads

RF absorbing tiles (three types)

Extensive program to find absorbers over the full frequency range at low temperature completed. Three different materials necessary Fabrication of first load nearly complete RFP ready to send to vendors for remaining loads

RF pickups

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SLIDE 34

June 22, 2006 JLab CASA Seminar 34

The fully dressed cavity

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SLIDE 35

June 22, 2006 JLab CASA Seminar 35

Cryomodule Design Concept

Cold Part of RF Power Coupler Motorized Frequency Tuner Cold He Gas Return Pipe Support Posts 2K Liquid Supply Line Piezo Tuners

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SLIDE 36

June 22, 2006 JLab CASA Seminar 36

Cryomodule Status

  • Fabrication of five two-cell cavities underway
  • First test of RF power coupler pair in July, with

procurement of ten more couplers to follow

  • First article HOM load test soon, procurement in

process

  • Blade tuner development underway in

collaboration with University of Pennsylvania

  • 2K cryogenic plant under construction
  • First horizontal test of fully dressed cavity early

in March 2007

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SLIDE 37

June 22, 2006 JLab CASA Seminar 37

1300 MHz RF Power Sources

  • 16 kW IOT transmitter in house, passed

acceptance test. Will be used for:

– RF power coupler tests – Buncher power – Transverse deflecting cavity diagnostic

  • 160 kW klystron in development at e2v

Technologies (England)

– First tube on pump stand, should begin RF testing in early July – First tube delivered in early August – Five additional tubes by April, 2007

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SLIDE 38

June 22, 2006 JLab CASA Seminar 38

First Klystron on Pump Stand

Klystron Specifications

  • > 120 kW CW output with

incremental gain > 0.5

  • Efficiency > 50% at 120 kW,

0.5 incremental gain

  • Small signal gain > 45 dB
  • +/- 2 MHz at – 1 dB
  • +/- 3 MHz at -3 dB

Seven cavity design required to meet specifications

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SLIDE 39

June 22, 2006 JLab CASA Seminar 39

Injector Layout in L0

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June 22, 2006 JLab CASA Seminar 40

L0 Layout with Mezzanine

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June 22, 2006 JLab CASA Seminar 41

Time Line

  • 750 kV Gun Power Supply delivered in

November 2006

  • Gun tests in lab continue through 2007
  • Begin clearing area for control room, and

starting installation later this year

  • Three (at most) horizontal cavity tests will be

completed by October 2007

  • L0 area ready for installation in November 2007
  • Begin beam operations in September 2008
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SLIDE 42

June 22, 2006 JLab CASA Seminar 42

ERL @ CESR

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SLIDE 43

June 22, 2006 JLab CASA Seminar 43

ERL @ CESR

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SLIDE 44

June 22, 2006 JLab CASA Seminar 44

Full Machine Planning

  • Detailed lattice design underway, with a total of

18 X-ray beam lines

  • Detailed WBS in development, prepatory to

developing a full budget and schedule for the full machine

  • Test borings of site underway with NYS funds
  • Six X-ray workshops held this month, to build

the science case for the full machine

  • Plan to submit a proposal for a 5 GeV ERL light

source in December, 2007

  • Construction start in 2011???