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Center for THz-driven Biological Systems

 

Nano-particle Based High Current Density Cathode for THz Application


 

 As RF sources move to higher frequencies, it becomes increasingly difficult to design and build high RF power generation due to limitation of the cathode emission capabilities. As a result generation of high current density beams directly from the cathode is critical need. In this point of view we need cathodes, which are capable of providing high current density, stable emission and uniform beam in order to attain high perveance and low compression ratio at lower operating temperature.

 We propose a novel nanoparticle-based high current density scandate dispenser cathode which can provide more than 100 A/cm2 current density. To achieve this, scandia doped tungsten nano-powder of average size of 50 nm was prepared using improved sol-gel method in order to obtained spherical shape, homogeneous mixing, uniform size and phase pure material.

 

Ⅰ. Cathode Development & Characterization

 

Thermionic Cathode Diagram

 

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Development of Cathode

 

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Analytical Chamber

 

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Ⅱ. Cathode Testing

 

        J2/3 vs. V plots at different temperatures         

 

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Graphene Based Field Emitter Cathode for THz Application


 

 As RF sources move to higher frequencies, it becomes increasingly difficult to design and build high RF power generation due to limitation of the cathode emission capabilities. As a result generation of high current density beams directly from the cathode is critical need. In this point of view we need cathodes, which are capable of providing high current density, stable emission and uniform beam in order to  low compression ratio at room operating temperature.

 We have developed a novel nanoparticle doped graphene based high current density field emitter  cathode which can provide more than 1000 A/cm2 current density. To achieve this, tungsten nano-particle doped reduced graphene oxide film was prepared using modified hydrothermal  method in order to obtained thin, free standing, and mechanically stable emitter.

 

Ⅰ. Film Heat Treatment and Shaping

 

 Heat treatment inside furnace       Unshaped, flexible film           Shaping using microtome

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 Film mounted into the holder     Emission testing chamber         Cathode inside chamber

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Ⅱ. Cathode Testing

           

                               J vs. V plot                                                          DC condition  

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                               F-N plot                                                              Stability plot

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