Study on the bc1 energy set point
Download
1 / 19

Study on the BC1 Energy Set Point - PowerPoint PPT Presentation


  • 131 Views
  • Uploaded on

Study on the BC1 Energy Set Point . J. Wu working with T.O. Raubenheimer, J. Qiang (LBL), LCLS-II Accelerator Physics meeting April 11, 2012. Layout. Previously BC1 @ 250 MeV for LCLS Pros and Cons of setting BC1 @ 300 ~ 350 MeV for LCLS-II

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Study on the BC1 Energy Set Point ' - erno


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Study on the bc1 energy set point

Study on the BC1 Energy Set Point

J. Wu

working with T.O. Raubenheimer, J. Qiang (LBL),

LCLS-II Accelerator Physics meetingApril 11, 2012

LCLS-II Accel. Phys. , J. Wu, SLAC


Layout
Layout

  • Previously BC1 @ 250 MeV for LCLS

  • Pros and Cons of setting BC1 @ 300 ~ 350 MeV for LCLS-II

    • Hardware consideration: cost and future 360 Hz operation

    • Macroscopic: chicane strength

    • Stability and tolerance

    • Microbunching instability: CSRTrack/IMPACT simulation indicating emittance growth during the compression, higher BC1 energy helps (example: Swiss XFEL moved BC1 from 256 MeV to 350 MeV)

LCLS-II Accel. Phys. , J. Wu, SLAC


Hardware consideration
Hardware consideration

  • Cost benefit for locating BC1 @ 300 ~ 350 MeV

    • Gird 11-3 is now the positron source, and it will be either replaced by a chicane or accelerator structure

    • Putting BC1 on gird 11-3 and keep RF cavities for gird 11-2 will be cost effective

  • Future 360 Hz operation will be running with unSLEDed cavities

    • Setting BC1 @ 300 ~ 350 MeV for 120 Hz will make it possible to still have the option of having BC1 @ 250 MeV for 360 Hz operation

    • Setting BC1 @ 250 MeV for 120 Hz operation will make it necessary to have cavities on gird 11-1 be SLEDed.

LCLS-II Accel. Phys. , J. Wu, SLAC


Chicane setup
Chicane setup

  • Assuming adding 200 MeV, so that the peak energy gain of is about 345 MeV between DL1 to BC1 (recall that for LCLS, it is about 145 MeV)

  • Keep setting the X-band at -160 degree, but vary the amplitude

  • One Example: setting BC1 energy @ 380 MeV and cancelling the second order curvature

    • L1S @ -21.8 degree (compared to ~ -22 degree)

    • L1X peak energy gain is 32.5 MeV (compared to ~ 20 MeV for LCLS)

LCLS-II Accel. Phys. , J. Wu, SLAC


Basic consideration
Basic consideration

Generic two bunch compressors system: after BC2

LCLS-II Accel. Phys. , J. Wu, SLAC


Optimization
optimization

Jitter model: normal distribution for the LINAC phases

LCLS-II Accel. Phys. , J. Wu, SLAC


Optimization1
optimization

Objective function: including de-chirping in L3

LCLS-II Accel. Phys. , J. Wu, SLAC


Optimization2
optimization

Analytically complete the integrals

LCLS-II Accel. Phys. , J. Wu, SLAC


Optimization3
optimization

Close form for the objective function with weight function: Wi,0

LCLS-II Accel. Phys. , J. Wu, SLAC


Layout1
Layout

  • BC1 @ 250 MeV

  • Set points

    • BC1: R56 = 45.5 mm, Energy 250 MeV, peak current 250 Amp

    • L1S: – 22 degree

    • L1X: – 160 degree; 20 MeV

    • L2: – 35.6 degree

    • BC2: R56 = 25.2 mm, Energy 4.3 GeV, peak current 3 kA

wire

scanner

4 wire-scanners

L0

L1X

L1S

gun

DL1

135 MeV

BC1

250 MeV

BC2

4.3 GeV

TCAV3

5.0 GeV

BSY

14 GeV

L3-linac

L2-linac

LCLS-II Accel. Phys. , J. Wu, SLAC


Profiles
Profiles

BC1

Final

CSR, LSC included in LiTrack, good agreement with Elegant [Bosch, Kleman, Wu, PRSTAB, 2008]

LCLS-II Accel. Phys. , J. Wu, SLAC


Layout2
Layout

  • BC1 @ 335 MeV

  • Set points

    • BC1: R56 = 39.5 mm, Energy 335 MeV, peak current 220 Amp

    • L1S: – 19.5 degree

    • L1X: – 160 degree; 30 MeV

    • L2: – 31.8 degree

    • BC2: R56 = 26.2 mm, Energy 4.3 GeV, peak current 3 kA

wire

scanner

4 wire-scanners

L0

L1X

L1S

gun

DL1

135 MeV

BC1

335 MeV

BC2

4.3 GeV

TCAV3

5.0 GeV

BSY

14 GeV

L3-linac

L2-linac

LCLS-II Accel. Phys. , J. Wu, SLAC


Profiles1
Profiles

BC1

Final

CSR, LSC included in LiTrack, good agreement with Elegant [Bosch, Kleman, Wu, PRSTAB, 2008]

LCLS-II Accel. Phys. , J. Wu, SLAC


Emittance
emittance

Example for BC1 @ 335 MeV: Impactsimulation

BC1 compressing to 250 Amp peak current does not see much slice emittance growth

LCLS-II Accel. Phys. , J. Wu, SLAC


Layout3
Layout

  • BC1 @ 380 MeV

  • Set points

    • BC1: R56 = 36.2 mm, Energy 380 MeV, peak current 300 Amp

    • L1S: – 21.8 degree

    • L1X: – 160 degree; 32.5 MeV

    • L2: – 29.6 degree

    • BC2: R56 = 25.7 mm, Energy 4.3 GeV, peak current 3 kA

wire

scanner

4 wire-scanners

L0

L1X

L1S

gun

DL1

135 MeV

BC1

380 MeV

BC2

4.3 GeV

TCAV3

5.0 GeV

BSY

14 GeV

L3-linac

L2-linac

LCLS-II Accel. Phys. , J. Wu, SLAC


Profiles2
Profiles

BC1

Final

CSR, LSC included in LiTrack, good agreement with Elegant [Bosch, Kleman, Wu, PRSTAB, 2008]

LCLS-II Accel. Phys. , J. Wu, SLAC


Tolerance
Tolerance

Assuming L1S has 0.06 degree rms phase jitter

BC1 @ 250 MeV

BC1 @ 380 MeV

1.36 %

3.95 %

LCLS-II Accel. Phys. , J. Wu, SLAC


Tolerance1
Tolerance

Assuming injector has 200 fsrms timing jitter

BC1 @ 250 MeV

BC1 @ 380 MeV

5.04 %

2.77 %

LCLS-II Accel. Phys. , J. Wu, SLAC


discussion

  • Linear compression study with optimization for BC1 @ 300 -- 350 MeV up to bypass line

  • Longitudinal profile up to bypass line

  • Tolerance study: peak current on timing and LINAC phase jitter up to bypass line

  • Transverse emittance degradation and microbunching instability with BC1 @ 335 MeV up to @ BC1 do not show much difference compared to the previous design with BC1 @ 250 MeV

  • Full machine lattice in Impact code is on going

  • Strong focusing on sec. 11-2

  • BC1 dipole strength: keeping same R56 will increase the B-field by 40 %, assuming same angle, same length

  • More tolerance study is needed: centroid energy, chirp, etc.

LCLS-II Accel. Phys. , J. Wu, SLAC


ad