LISA GRS FEE test campaign at ETH Zürich
Luigi Ferraioli, Davor Mance, Jan ten Pierick, Jonas Zollinger, Peter Zweifel and Domenico Giardini
Departement Erdwissenschaften, Institute of Geophysics, ETH Zürich
LISA GRS Front End Electronics
The TM is electrostatically suspended between
surrounding electrodes and its motion along x or φ
causes an imbalance in capacitance, i.e. in
currents in primary windings of both transformer
bridges (between electrodes A+/- and B+/-). The
imbalance in currents reflects in the level and sign
of the current flowing in the secondary winding of
each transformer. The corresponding preamplifier
detects the current and converts it to a voltage.
The TM is biased by 100 kHz AC bias via separate
injection electrodes. To allow for high sensitivity of
capacitive measurement, the transformer with high
quality factor Q is operated at resonance matching
the injection bias frequency, for which capacitors
are added in parallel with primary windings. As the
output of the preamplifier is an amplitudemodulated signal with amplitude representing the
displacement, the injection bias reference (carrier)
signal is also needed for the phase-sensitive
detectors in the sensing circuitry chain (the
demodulators).
In order to reduce the stray acceleration on TM, the
force signal are provided by numerically synthesized
AC waveform at low audio frequencies (60 – 270 Hz).
To apply strong forces on TM in the Wide Range (WR)
Mode, large AC voltages are used. The force signal
for each electrode is Digital to Analog converted and
amplified by a corresponding Drive Voltage Amplifier.
The actuation signals are further low-pass filtered to
reject higher frequencies that could interfere with the
sensing circuitry.
LISA GRS FEE Test Campaign – Test Setup
Test Script
Send Commands To
EGSE
User Interface
Parameters setting
UDP
Instructions
Read Data From
EGSE
Commands File
Launch LabVIEW
Virtual Instrument
EGSE
GPIB
Tests of actuation performances do not require TM
simulator. Actuation signals are read by test equipment
(e.g. Digital Multimeter, Lock-In Amplifier) that is controlled
by LabVIEW.
Tests are executed by MATLAB Test Scripts.
Test Equipment
LabVIEW
Commands Generating
Script
TM
Simulator
FEE
Tests of sensing performances require a Test Mass
Simulator. Sensing data are acquired by the FEE sensing
electronics and sent to the controlling PC by the EGSE via
the UDP interface.
Store Data and Log
Test scripts read ASCII files with the instructions for the EGSE and the test
schedule.
MATLAB
Raw data are converted to
Analysis Objects and
analyzed with LTPDA.
LTPDA Repository
Analysis PC
LTPDA
Raw data and analysis
products are finally stored
i n t h e l o c a l LT P D A
repository.
WR mode Noise
at performance
and max ranges
Classic Scheme
1
10
HR and WR
modes voltage
noise
~ 1 pF
~ 120 pF
0
−4
10
−3
10
−2
10
Frequency [Hz]
−1
10
0
1
10
10
Instead of dual 1 pF capacitor simulator a
triple capacitor design is implemented using
large capacitors
The nominal current trough the transformer is
maintained and the resonance tuning
capacitance is adapted to maintain the total
required capacitance
The parasitic capacitances now have
negligible effect on large simulator capacitors
Preliminary results with a prototype
since their value is ~ 100 times larger than old
design
Variation between the capacitors have ~ 100
times smaller effect on the noise
-2
10
HR Mode Sensing Noise Requirement @ performance range
ASD(TM_3_caps.dat)
ASD(TM_3_caps_bridge.dat)
ASD(no_TM.dat)
Limit: 1aF/√ Hz (HR noise shape)
-3
10
LTPDA 2.7.dev (R2013a)
2014−05−13 12:30:28.877 UTC
ltpda: f9f9e45
iplot
-4
2
10
10
-5
10
-6
10
-7
10
-4
10
1
10 −5
10
Injection and plunger
amplitude stability
~ 120 pF
~ 155 pF
[µV Hz−1/2]
Actuation
performance
New design proposed by
~ 1 pF
10 −5
10
HR and WR
modes amplitude
stability
Data from EGSE and LabVIEW are stored in ASCII files.
[V Hz-1/2]
Sensing
performance
LabVIEW VIs are launched as background jobs.
[aF Hz−1/2]
HR Mode Noise
at performance
and max ranges
EGSE is controlled via the UDP interface provided by the Instrument Control
Toolbox.
Test Mass Simulator
LISA GRS FEE Test Campaign
LTPDA 2.7.dev (R2013a)
2014−05−13 12:18:13.390 UTC
ltpda: f9f9e45
iplot
Test scripts are standardized and require only minimal user customization.
−4
10
−3
10
−2
10
Frequency [Hz]
−1
10
0
10
1
10
HR Mode Actuation Amplitude Stability Requirement
-3
10
-2
10
Frequency [Hz]
-1
10
0
10
1
10
Luigi Ferraioli et. al., 10th International LISA Symposium, University of Florida, Gainesville, Florida USA, May 18 - May 23, 2014
Email: luigi.ferraioli@erdw.ethz.ch