27 Nov 2013
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Ferroelectric Cathode Experiments :
PDFs:
Initial Ferroelectric Experimental Results Simple Diode Configuration, 26 May 2013; here the first experimental test is described (at 5E-6 torr). A schematic shows the trigger pulse manually applied to the cathode; and the anode circuit. The experimental results amazed me; the anode operating below 1KV with an associated 15 amp pulse; worked better than I expected.
1st Ferroelectric Test Sample, 15 May 2013
Simple Diode Configuration, 23 May 2013 ; this PDF briefly describes the initial test chamber setup ( see right photo above). It provides a view , through the observation window, the anode and ferroelectric cathode. Also the initial vacuum process for slowly outgassing is mentioned.
For some time I have been interested in conducting small volume electron beam experiments. Hot cathode electron sources seemed rather involved but can be made doable with lots of patience; however what really got my attention is the ferroelectric cold cathode effect, see references listed below, seemed less involved than thermionic emission. Based on this information I suspected that HV ceramic capacitors could be modified for ferroelectric emission ( see left photo); . To test this out an experimental test vacuum chamber was assembled (see right photo). A listing of the PDF (and associated abstracts) links describing my experiments is given below.
Some of the References My Experiments Based On :
"the ferroelectric cathode a new option for microwave tubes", M. Einat, E. Jerby and G. Rosenman IEEE POTENTIALS AUGUST/SEPTEMBER 2002
"Annular Electron Beam Generation Using a Ferroelectric Cathode", Czeslaw Golkowski, Donald Flechtner, , Jim D. Ivers, John A. Nation,
and Levi Sch¨achter, IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 26, NO. 3, JUNE 1998
"Polarization switching in ferroelectric cathodes ", G. Rosenman, D. Shur, Kh. Garb, and R. Cohen, Ya. E. Krasik, J. Appl. Phys. 82 (2), 15 July 1997
"Electron-beam diodes using ferroelectric cathodes", J. D. Ivers, L. SchSlchter, J. A. Nation, G. S. Kerslick, and R. Advani Laboratory of Plasma Studies and School of Electrical Engineering, Cornell University, Ithaca, New York 14353, J. Appl. Phys. 73 (6), 15 March 1993
"NEW RESULTS ON ELECTRON EMISSION FROM PZT FERROELECTRIC CATHODES", D. Flechtner, Cz. Golkowski, J. D. Ivers, G. S. Kerslick, J. A. Nation, and L. Sch¨achter Laboratory of Plasma Studies & School of Electrical Engineering, Cornell University, Ithaca, NY 14853, USA 1998 IEEE
"A FERROELECTRIC CATHODE, ELECTRON GUN FOR HIGH POWER MICROWAVE RESEARCH", J. D. Ivers, D. Flechtner, Cz. Golkowski, G. S. Kerslick, and J. A. Nation Laboratory of Plasma Studies & School of Electrical Engineering, Cornell University, Ithaca, NY 14853, USA, 1998 IEEE
"High-Power Microwave Generation Using A Ferroelectric Cathode Electron Gun", Yasushi Hayashi, Member, IEEE, X. Song, J. D. Ivers, Donald D. Flechtner, Member, IEEE, J. A. Nation, Fellow, IEEE, and Levi Schächter, Senior Member, IEEE, IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 29, NO. 4, AUGUST 2001
"Demonstration of microwave generation by a ferroelectric-cathode tube", R. Drori, M. Einat, D. Shur, E. Jerby,a) G. Rosenman Faculty of Engineering, Tel Aviv University, Ramat Aviv 69978, Israel R. Advani and R. J. Temkin Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 C. Pralong Paul Scherrer Institute, CH-5232 Villigen, SwitzerlandE Appl. Phys. Lett., Vol. 74, No. 3, 18 January 1999
High-repetition-rate ferroelectric-cathode gyrotron" , M. Einat, E. Jerby,a) and G. Rosenman Faculty of Engineering, Tel Aviv University, Ramat Aviv 69978, Israel Appl. Phys. Lett., Vol. 79, No. 25, 17 December 2001
"A Microwave Gyro AmplifierWith a Ferroelectric Cathode", Moshe Einat, Eli Jerby, and Gil Rosenman IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 50, NO. 4, APRIL 2002
Vacuum Page
Continuation Ferroelectric Experimental Results Simple Diode Configuration 1 June 2013 ; Operating Pressure ~ 6E-6 Torr; replace manual trigger with IGBT cathode driver ; PRF set by trigger generator. Test at 18 KV discharging 500 pF capacitor ; 30 amps peak.
Further Ferroelectric Experimental ResultsSimple Diode Configuration 2 June 2013; basically repeat previous replacing the 500pF with a 2.7 nF capacitor; at least 100 amps peak.
5 June Ferroelectric Experimental Results Simple Diode Configuration Test Anode at 6KV 500pF 5 June 2013 ; The IGBT driver is replaced with a triggered SG 10 ohm PFN ferrite cathode driver. Test anode with 500pf capacitor at 6KV.
6 June Ferroelectric Experimental Results Simple Diode Configuration Test Anode at 12KV 1.7nF 6 June 2013 (at 3.5 E-6 Torr) ; "The system was operated for about 3 hours at 12KV ( anode to GND switching Photo 3)at a pulsed peak current of 150 Amps (Photo 4). I didn’t observe any sputtering; only tiny scinilations. I did test it at 22KV; placed my Geiger counter at the observation window; got a click in step with the trigger."
The ferroelectric effect was observed, during my experiments, even at a few hundred volts associated with strong electrical conduction when the anode was set positive. When the power supply's negative potential was conducted to the anode very little current was observed; suggesting conduction is mainly due to electron emission and less so to ions. As for vacuum the ion gauge, although not located in the test chamber, indicated vacuum less than 1E-5 torr for most experiments in an attempt to keep the ion value down. Many of the references describe ion plasme formation on the ferroelectric surface; I observed is that when the ferroelectric cathode sample was first installed plasma flash bursts were observed traveling around the ceramic surface; but quickly disappeared with usage. Eventually only tiny scintillation flashes could be seen. I plan to investigate this phenomenon further in the future; however my vacuum system needs cleaning and flushing out. My objective is determine whether this effect can be used for my electron beam experiments.