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Updated: May 12, 2026

Non-equilibrium Microwave Plasma for Efficient High Temperature Chemistry
Published on: August 1, 2017
A microwave interferometer for small and tenuous plasma density measurements
O Tudisco1, A Lucca Fabris, C Falcetta
1ENEA CR Frascati, Via E. Fermi 45, 00044 Frascati, Italy. onofrio.tudisco@enea.it
Abstract:
The non-intrusive density measurement of the thin plasma produced by a mini-helicon space thruster (HPH.com project) is a challenge, due to the broad density range (between 10(16) m(-3) and 10(19) m(-3)) and the small size of the plasma source (2 cm of diameter). A microwave interferometer has been developed for this purpose. Due to the small size of plasma, the probing beam wavelength must be small (λ = 4 mm), thus a very high sensitivity interferometer is required in order to observe the lower density values. A low noise digital phase detector with a phase noise of 0.02° has been used, corresponding to a density of 0.5 × 10(16) m(-3).
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