Primary Beam Test of Cavity BPM

Shu-xin ZHENGAccelerator Laboratory

Tsinghua University

Content Introduction Main parameter Primary Beam Test

introduction Goal

XFEL: m ILC : nm

Program Collaborated between SSRF/SINAP and Tsinghua University

Cavity Parameter

Parameter Value UnitLength 20 mmBeam pipe radius 10 mmFrequency 5712 MHzResolution 10 m

Partially welded

Cavity BPM Picture

Microwave parameter

Port F(MHz) Qe Q0X position 5709.9 1.9104 1.6104

Y position 5710.4 1.8104 1.3104

Ref. Cavity 5717.2 7.9103 1.8103

Primary Beam Test Laser RF Gun

Charge: 700pC Dark current: 20nC Position jetter: 0.1mm Length: 4~7ps

Experiment Setup

RF GUN

Deflectin

g Coil

CavityBPM

YAG

Screen

1.5m0.15m

Beam Signal

YAG Screen Monitor

Beam Position on YAG vs. Coil Current

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4-5

0

5

10

15

20

25

Deflecting Coil Current (A)

Beam Po-sition (mm)

=0.24mm

Position Signal

-5 0 5 10 15 20 250

10

20

30

40

50

60

70

80

90

f(x) = − 4.68296618612391 x + 71.2046925479128R² = 0.992867312125969

Beam Positon (mm)

Pos

itio

n S

ign

al (

mV

) =1.8mm

Resolution Voltage noise

v=1.8mm4.7mV/mm=8mV Mainly from dark current?

Resolution@0.7nC 1.8mm/11.6=0.16mm

Error Dark current Trace tilt

Thank you for your attention