Conferences
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Structure-specific THz response on DNA condensation
International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz
Son H., Choi D.-H., Jung S., Park J., Cheng R.H., Park G.-S.
Abstract
DNA conformational change is proved in THz frequency range. Distinct difference in absorption of condensed and extended DNA is observed. The result suggests that THz spectroscopy identifies global change in DNA structure sensitively. © 2013 IEEE.
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Analysis of the three types of folded waveguide slow-wave structure for 140GHz t...
IEEE International Vacuum Electronics Conference, IVEC 2014
Guo G., Wei Y., Gong Y., Duan Z., Park G.-S.
Abstract
Three types of folded waveguide slow-wave structure (SWS) are analyzed and compared for 140GHz traveling wave tube (TWT). The radio frequency characteristics and the large signal beam-wave interaction performances of the three SWS are simulated and compared. The loaded ridge can improve the output power and the tapered ridge can reduce the mismatch between the SWS and the ridge. © 2014 IEEE.
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Suppression of TE mode oscillation in PPM-focused S-band sheet beam klystrons
IEEE International Vacuum Electronics Conference, IVEC 2014
Sattorov M., Kwon O., Min S.-H., Park G.-S., Scheitrum G., Perkins M.P., Burke A.T.
Abstract
The suppression of TE mode oscillations in a PPM-focused S-band sheet beam klystron amplifier using a method of loading distributed losses is presented. This method allows us to make a reasonable attenuation of unwanted modes relative to the operating TM mode and can be used to improve the stability of beam-wave interaction circuit with high aspect ratio. © 2014 IEEE.
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Nanoparticle-ba
sed thermionic cathode for THz device application 2014 10th International Vacuum Electron Sources Conference, IVESC 2014 and 2nd International Conference on Emission Electronics, ICEE 2014 - Proceedings
Barik R.K., Bisht M.S., Raju R.S., Park G.-S.
Abstract
A high-current-density, long life and uniformemission cathode is a key requirement for a THz-VED. Using a new synthesis approach Sc2O3 doped W-nanoparticles were made to fabricate cathode, which is believed to play a dominant role for above application. The fabrication details along with the emission results will be presented. © 2014 IEEE.
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Salt-induced change in lipid hydration
International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz
Choi D.-H., Son H., Jeong J.-Y., Park I.-K., Park G.-S.
Abstract
We investigate the ion effect on 1, 2-ditetradecanoyl-sn-glycero-3-phosphocholine lipid hydration with attenuated total reflection terahertz time domain spectroscopy. The absorption difference between lipid solutions and buffers (water and NaCl solution) shows that lipid-ion interaction accelerates the water reorientation motion confined in nanometer scale structure. © 2014 IEEE.
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Enhanced radiation in a modified me
tallic me tamaterial driven by pre-bunch... Proceedings of 2015 IEEE International Vacuum Electronics Conference, IVEC 2015
Kim S., Baek I.-K., Kwori O., Bera A., Bhattacharya R., Sattorov M., Min S.-H., Park G.-S.
Abstract
Modified metallic metamaterials are known to provide external radiation from Cerenkov-like modes which can be excited using an electron bunch. Extremely strong electromagnetic field enhancement could be formed for compact, efficient free-electron lasers with open metallic structures. The numerical and experimental works will be presented in detail. © 2015 IEEE.
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Electromagnetic field enhancement in me
tallic me tamaterials : A potential ... IRMMW-THz 2015 - 40th International Conference on Infrared, Millimeter, and Terahertz Waves
Kim S., Baek I.-K., Kwon O., Bera A., Bhattacharya R., Matlabjon S., Min S.-H., Park G.-S.
Abstract
Our recent efforts suggest that there exists strong electromagnetic field enhancement in our recently proposed metallic metamaterial. Of particular importance here is the potential for the realization of compact terahertz free-electron lasers (THz-FELs) using this structure. We present the capability of controlling electromagnetic field enhancement, which must be one of the main issues in developing the compact THz-FELs. Moreover, switching and sensing abilities of this structure could also be investigated for other metal-based THz applications. The numerical and experimental works will be presented in the conference. © 2015 IEEE.
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Investigation of emission capability of reduced graphene oxide film cathode for ...
IRMMW-THz 2015 - 40th International Conference on Infrared, Millimeter, and Terahertz Waves
Bhattacharya R., Baek I.-K., Lee J.S., Barik R.K., Kim S., Hong D., Kwon O., Sattorov M.A., Kim Y.H., Park G.-S.
Abstract
Terahertz vacuum sources with high power are in immediate need for several applications like medical, security, communication, etc. The power and performance of these devices mainly depends on cathode. As structure become smaller, it is very much difficult to obtain high power at terahertz frequency, using conventional low current density thermionic cathodes. As a result development of non-conventional field emission cathode is in progress, which may produce a very high current density with comparatively high current and can help in terahertz research and application. In this work our main aim is to develop and analyze high current density (>103A/cm2) sheet beam film cathode using reduced graphene oxide (rGO)-nano particle composite. © 2015 IEEE.
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Conditioning of vertically aligned reduced graphene oxide film electron emitter ...
IRMMW-THz 2015 - 40th International Conference on Infrared, Millimeter, and Terahertz Waves
Baek I.-K., Bhattacharya R., Lee J.S., Kim S., Hong D., Ohjoon K., Kim Y.H., Park G.-S.
Abstract
The field emission from the edge of vertically aligned reduced graphene oxide (rGO) film was examined experimentally. High current (I > 5 mA) and high emission current density (J > 100 A/cm2) was obtained using diode configuration. The thermal runaway of sharp protrusions on emission edge are considered to be source for the destructive vacuum breakdowns due to high local emission current. A remarkable field emission stability was achieved using processed field induced evaporation, by removing the protrusions and recovering the totally field emission attributed I-V characteristics. © 2015 IEEE.
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Accelerated terahertz water dynamics under osmotic interaction of lipid bil
ay... IRMMW-THz 2015 - 40th International Conference on Infrared, Millimeter, and Terahertz Waves
Eom K., Son H., Jeong J.-Y., Jang J., Park I.-K., Kim S., Park G.-S.
Abstract
Intracelluar water is expected to have different physical properties from those of bulk water. Using polyethylene glycol, we induce model intracellular environment on DMPC lipid solution and we shows the accelerated movement of non-hydrogen bonding (NHB) water molecules interacting with DMPC in polyethylene glycol (PEG) solution from the dielectric response in the terahertz range. With the measurement in the GHz range, detailed behavior of hydration water is also analyzed. © 2015 IEEE.
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