Seok-Gy Jeon

Learn More
A new vacuum-channel transistor with a carbon nanotube cathode and nanometer-scale channel length-called a slit-type vacuum-channel transistor is proposed and investigated. The suggested device structure features distinguishable cutoff, linear, and saturation regions with a negligible gate leakage current. Its channel length is almost the same as the mean(More)
We investigated foundations for high frequency vacuum electron devices, experimentally with emphasis on LIGA (deep etch X-ray lithography: lithographie, galvanoformung, abformung; German acronyms) to fabricate a miniaturized interaction circuit and a photonic crystal (PC) resonator to excite a stable high order mode. The successful operation of a(More)
We demonstrate high speed scanning of a time-domain terahertz pulse by a rotary optical delay line (RODL) incorporated into a photoconductive antenna based terahertz system. The delay line of RODL consists of six rotating convex reflective blades with a rotating speed controlled for a wide range of scan repetition rates. It can perform path length scans of(More)
100 GHz linear magnetron employing the ten-vane reentrant resonator is investigated by using a two-dimensional particle-in-cell simulation. The dynamics of electron beam, the time variation of electric energy in each vane, and the generated power density are examined when the injected current density is varied. The maximum power density is 180(More)
We describe a fast measurement of a pulsed terahertz signal generated by a femtosecond laser and a photoconductive antenna using an oscillating optical delay line. The method to measure the amplitude of the retroreflector in the oscillating optical delay line is proposed and the displacement of the retroreflector is exactly calculated to acquire the optical(More)
We investigate, using the 3-D particle-in-cell simulation code MAGIC, the millimeter-wavelength 20-vane magnetron operating at one of the spatial nonfundamental harmonics of the backward-traveling wave. This spatial harmonic is characterized by 16 (<i>p</i> = 16) RF electric field variations along the circumference of the magnetron interaction space(More)
We demonstrate the application of terahertz time domain spectroscopy (THz-TDS) for analysis of petroleum products and organic solvents. Refractive index, absorption coefficient, and dielectric constant of gasoline, diesel, kerosene, and organic solvents such as xylene, toluene, and benzene were analyzed in the spectral range of 0.2 - 2 THz. Variation of(More)
A 35 GHz 3 kW spatial-harmonic magnetron employing 20-vane resonator is numerically and experimentally investigated. Simulated output power is 3.2 kW at beam voltage of 6.5 kV and anode current of 4 A using 3D PIC simulation. The measured resonant frequency for operation mode of p &#x003D; 16 is 34.96 GHz.
We demonstrated a novel point-typed carbon nanotube field emitters using a triangular-shaped carbon nanotube films. We also investigated the field emission properties of the field emitters according to the tip angles. The wider field emitters exhibited higher emission current, and the field emitters with a tip angle of 120&#x00B0; showed extremely high(More)
Physical characteristics of a dc-biased single-surface multipactor are investigated theoretically, and a novel scheme of the multipactor using a photonic crystal cavity resonator to maximize insulation gap distance is introduced. A fixed rf phase minimizing rf electric field is analytically obtained, which is universal for any surface material. With an(More)