Quadrupole Vibration Measurements

1
Quadrupole Vibration Measurements in the FFTB at
SLAC
Rachel Fenn, Tim Slaton, Mike Woods 08/23/99
Refer to report by Rachel Fenn (http//www.slac.s
tanford.edu/th/erulf-sise/rafen)
This work was part of the DOE ERULF summer
student program (formerly SLAC SISE)
Goals of project 1. Repeat vibration data
measurements for QM1B magnet, which was claimed
to have very good results at time of ZDR, but
was not documented well. Quantify results. 2.
Take vibration data on a different type of
quadrupole magnet in FFTB. Quantify
results. 3. Develop standard datataking and
analysis procedures.
2
FFTB Quadrupoles Measured
QC3
QM1B
Beam height approx. 5 feet
3
QC3
4
FFTB QM1B Vertical STS-2 data
ZDR p. 395 Seismometer measurements that were
made on top of the quadrupoles and on the floor
in the FFTB show that there is only a few nm of
relative motion (fgt0.1 Hz) between them when
the quadrupoles are powered. (no reference or
figure given to support this)
11/22/95 0200
5
FFTB rf BPM Box at IP image Vertical Geophone Data
04/28/97 1400
6
Setup and Datataking 2 vertical geophones (1
on quad, 1 on floor) 2 horizontal geophones (1
on quad, 1 on floor) Geophones are Mark L-4C.
Resonant frequency is 1 Hz. Voltage output
velocity. Datataking using Labview on a PC to
read out 4-channel NI AT-A2150 DAQ board with
16-bit resolution. Sampling frequency is 256 Hz.
Save data for analysis with Matlab. (Analysis
sets average velocities 0)
1-128 Hz frequency range
7
2 vertical geophones side-by-side on floor in FFTB
8
FFTB QM1B vertical geophone data
9
FFTB QM1B vertical geophone data
10
FFTB QM1B vertical geophone data
11
FFTB QM1B 24-hours of data
12
Estimating Luminosity Loss due to QM1B vertical
vibrations
Assume colliding beam offset, Dy y(QM1B)
Assume,
no feedback
Feedback algorithm used is a next pulse feedback
with feedback
Time (seconds)
13
Estimating Luminosity Loss due to QM1B vertical
vibrations
Assume colliding beam offset, Dy y(QM1B) -
y(floor)
Assume,
Feedback algorithm used is a next pulse feedback
with feedback
Time (seconds)
14
FFTB QM1B horizontal geophone data
15
FFTB QM1B horizontal geophone data
16
FFTB QM1B horizontal geophone data
17
FFTB QC3 vertical geophone data
18
FFTB QC3 vertical geophone data
19
FFTB QC3 vertical geophone data
IP_diff(3Hz)25.0nm (2Hz)25.0nm
(1Hz)25.3nm
20
FFTB QC3 horizontal geophone data
Time (seconds)
21
FFTB QC3 horizontal geophone data
22
FFTB QC3 horizontal geophone data
IP_diff(3Hz)63.8nm (2Hz)63.9nm
(1Hz)64.3nm
23
Summary and Conclusions
24
Comments - new QM1B data is consistent with
earlier data would be good to take data with
STS-2 down to 0.1Hz and combine with geophone
data to cover range 0.1 - 128 Hz - high
frequency data (60-120Hz) can be important -
important to understand QC3 data better. Take
data with water off - QM1B data is
encouraging for meeting NLC requirements, but
QC3 data illustrates some of the challenges
ahead - vibration data on NLC prototypes is
needed
To do - check results for luminosity loss
and try 6-pulse exponential feedback
algorithm analyze power specta for this
analysis - document this work in an LC-Note