Prime pagine RA2010FUS:Copia di Layout 1 - ENEA - Fusione

120
progress report
2010
Figure 9.5 – LOFT, with the detectors folded, in the ogive of the
launcher
detectors) in the 2–30 keV range (fig. 9.4). The achievable time–resolution of
its x–ray observations of compact objects would constitute a relevant
diagnostic for strong–field gravity and the equation of state of ultra dense
matter. LOFT has been presented in December 2010; to date it has been
selected (with other 13, out of 47 proposals) for further consideration by the
Advisory Structure of the ESA Scientific Programme.
Figure 9.6 – Elecronic equipment for the RF interferometer for helicon
plasma hydrazine
Standard deviation (Deg)
20
10
5
3
1
0.5
0.2
0.1
0.05
0.02
10
implementation and is based on an ENEA electronic patent.
9.4 Digital Phase Detector for the RF
Interferometer for Mini Helicon Space Thruster
Within the HPH.com project a RF interferometer has been built for the mini
helicon thruster at the CISAS laboratory (Padua). This interferometer is
capable of detecting a phase variation of 0.3° within the band 0–15 kHz, and
0.06° within the band 0-100 Hz. This instrument has been used to detect the
density of the plasma generated by the thruster (which is a small cylindrical
plasma with 20 mm of diameter) with an error of 4×10 16 m –3 in the band
0–15 kHz, and of 1×10 16 m –3 in the band 0–100 Hz.
20 40 60 80
Attenuation (dB)
Figure 9.7 – Total error (including the linearity error)
vs attenuation
Commercial analog I/Q detectors for
phase shift measurements introduce an
error not less that 1°, so a dedicated phase
detector, with appropriate noise figures
(0.02°), has been developed, tested and
successfully integrated for the RF
interferometer. It is based on a digital
elaboration system that implements a
vector voltmeter working at the frequency
of 100 MHz and measures the complex
components of the signal under test as
compared
The system sends the elaborated data to a
PC, via an ethernet port at a speed of
31thousand measurements per second. On
the PC a GUI able to start receiving is
present, which saves the data and allows
for a preview of decimated data.
Furthermore, the system shows on a 4–line
LCD the value of the module and the
phase instantaneously measured.
The system calculates the quadrature
components, has a fully digital
The advantages of this system are high linearity, high measurement frequency and high noise immunity, see
figure 9.7.