Design and characterization of an ion source for neutron production

Summary form only given.The piezoelectric transformer plasma source (PTPS) was studied as a possible ion source for neutron production. The PTPS consists of lithium niobate disc, a piezoelectric material, placed between a driving electrode and an annular ground electrode on its surfaces. When the PTPS is driven through the thickness with an rf voltage at the crystal resonant frequency a radial resonance is generated. The mechanical resonance in turn generates high voltage on the top face of the crystal within the annular ground electrode. The high electric field generated in the aperture of the ground electrode leads to the formation of a plasma on the surface of the source. The charged particles in the plasma are accelerated through a series of apertures and extracted using an extraction voltage applied to a plate at some distance. A Z-cut lithium niobate (LiNbO3) crystal rotated 45° about the x-axis was used as the piezoelectric material in the PTPS, because of the high voltages possible from the crystal as a result of efficient piezoelectric coupling. Argon gas was differentially pumped directly into the area of high potential where the plasma formation occurred. Ion current was measured for gas pressures from 500 to 4000mTorr, apertures of varied sizes and characteristics, extraction voltages up to 5kV and extraction gap distances of 0.5, 1, and 2cm. Experimental results will be presented.