E200 PWFA Collaboration Meeting

TCAV

April 12, 2013

M. Litos

Study of TCAV profile monitor location for new FACET optics

Sector 20 vertical (y) beta function for new optics provided by Glen White on 1/28/13

TCAV

USTHz

DSTHz

by,TCAV = 53.09mby,USTHz = 14.94mby,DSTHz = 3.78mby,min = 23cm

sTCAV = 39.93msUSTHz = 54.50msDSTHz = 55.30msmin = 56.19cm

Sector 20 vertical (y) phase advance for new optics provided by Glen White on 1/28/13

TCAV

USTHzDSTHz

yy,TCAV = 0.703pyy,USTHz = 0.995pyy,DSTHz = 0.960pyy,min = 1.593p

sTCAV = 39.93msUSTHz = 54.50msDSTHz = 55.30msmin = 56.19cm

Min b

sin(yy – yy,TCAV)

TCAV

USTHz

DSTHzsinDyy,TCAV = 0sinDyy,USTHz = 0.73sinDyy,DSTHz = 0.80sinDyy,min = 0.33

Min b

sin(yy – yy,TCAV)Zoomed View

TCAVConclusion: DSTHz is better location for TCAV profile monitor than USTHz with new FACET optics

sinDyy,TCAV = 0sinDyy,USTHz = 0.73sinDyy,DSTHz = 0.80sinDyy,min = 0.33 Min b

USTHz

DSTHz

More important conclusion: monitoring the beam at the waist decreases the streaking strength to ONE THIRD of the nominal max strength! The betatron phase advances very quickly just before and after the waist, and can blow right past the 90 degree point from the TCAV, significantly reducing the resolution of the measurement. This is possibly the reason we saw a factor of ~2 or so reduction in streaking strength during the 2012 run when going from E200 config to “TCAV optimized” config.

Unstreaked beam on 1um foil

First streaked beam of 2013 on 1um foil

Unstreaked Beam on 20um YAG

Streaked Beam on 20um YAG

June 5, 2012R56 = 10mm

Note: Axis labels are flipped and calibration is unreliable, but image is in correct orientation. Beam is streaked in vertical direction. Longitudinal bunch separation measured to be ~150um.

March 24, 2013Pencil Beam – No Compression

Note: Axis labels are correct and calibration is good. Beam is streaked in vertical direction. Longitudinal bunch separation measured to be ~1200um.

March 24, 2013Pencil Beam – Compressed

Note: Axis labels are correct and calibration is good. Beam is streaked in vertical direction. Horizontal dispersion present. Longitudinal bunch separation measured to be ~200um.

TCAV GUI Kick Measurement

TCAV GUI Bunch Length Measurement

Summary

• TCAV is kicking ass this year!• Addition of YAG to prof. mon. gives good

photon yield even when streaked• Using DSTHz window gives clear line of sight,

better magnification and resolution• Lower beta function optics = more stable beam

w/ lower chromatics• Careful examination of phase advance to guide

desired beta func., which happens to be nominal value

• Improved calibration of RF equipment in control system

• RF controls feedbacks to stabilize phase & amp• GUI for fast bunch length measurement• WIP: integrate profile measurement with sYAG

online beam characterization tool