טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentSagie Hila
SubjectGeneration of A high-Intensity Micro-particle Flux during
Operation of A Ferroelectric plasma Source
DepartmentDepartment of Physics
Supervisors Professor Yakov Krasik
Professor Emeritus Joshua Felsteiner


Abstract

In this research we preformed time- and space-resolved characterization of high-intensity micro-particle flux emitted from the front surface of a ferroelectric plasma source (FPS). The FPS is subjected to a driving pulse with a slow rise and fast fall time. This type of plasma source can be used as a sources of a relativistic high-current electron beam with current density up to 103 A/cm2, pulse duration up to 10-6 s, and cross-sectional area up to 103 cm2 at accelerating electric field in the range of 104 - 105 V/cm.

It was found that formation of incomplete discharges on the surface of the ferroelectric is accompanied not only by intense electron/ion and neutral flows but also by emission of an intense micro-particle flow. This micro-particle flow was studied using different electrical and non-disturbing optical diagnostics at several distances from the ferroelectric sample front surface and at several time delays with respect to the fast fall of the driving pulse. Using these methods, average size, average velocity, velocity distribution, density and average charge of the micro-particles were determined. Namely, it was shown that the micro-particles are positively charged and they have average size of ~ 5 µm, density of ~ 7×104 cm-2, and average velocity of ~ 60 m/s.

 We suggest a possible mechanism based on a converse piezoelectric effect which can explain formation of micro-particles flows. Our estimate shows that the appearance  of inhomogeneous electric field in the ferroelectric crystal creates mechanical stress sufficient for breaking the chemical bonds of the ferroelectric surface.

The application of the obtained micro-particle flow as a propellant for a small thruster is discussed.