• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.20 no.3
• /
• pp.342-349
• /
• 2011

The purpose of this paper is to describe experimental results about the butt welding and bead on plate welding of the high power Continuous Wave (CW) Fiber laser for Ultra-low carbon Interstitial Free(IF) steel plate for gear part of car. After being welded of the gear parts by the fiber laser and electron beam Microstructures of melting zone had been mixed acicular, granular bainitic, quasi-polygonal and widmanstatten ferrite because of a radical thermal diffusion after welding, difference of critical volume and grain size. As a result of experiment, when gear parts were welded by the fiber laser and electron beam, the fiber laser welding has been stable properties without internal defects more than the electron beam welding. Therefore it has the very advantages of welding high quality and productivity more than conventional melting method. The optimal welding processing parameters for gear parts were as follows : the laser power and welding speed were 3kWatt, 30mm/sec respectively. At this time heat input was $21.2{\times}10^3J/cm^2$.

• Proceedings of the Korean Nuclear Society Conference
• /
• 2004.10a
• /
• pp.672-673
• /
• 2004

• Journal of the Korean Physical Society
• /
• v.73 no.10
• /
• pp.1495-1501
• /
• 2018

We have developed an extended three-dimensional free-electron laser (3D FEL) code with source-dependent expansion to calculate the intensity of the radiation field and the spot size in a free-electron laser oscillator. The effect of the wiggler field errors was evaluated for the case of a planar wiggler generated by a magnet stack with parabolic shaped pole faces by using the extended three-dimensional equations in a free-electron laser oscillator based on the proposed FEL facility which is to be operated in the far-infrared and the infrared regions. The radiation spot size due to the wiggler field errors also have been analyzed for wiggler errors of ${\Delta}B/B=0.0$, 0.03, 0.06 and 0.09% at z = 1 m and z = 2 m. The effect of the diffraction of radiation field due to the wiggler field errors of ${\Delta}B/B=0.0$ and ${\Delta}B/B=0.09%$ at 200 passes was evaluated by using the extended 3D code that we developed. The variation of the curvature of the phase front and the effect of the radiation field intensity due to the wiggler field errors were also evaluated for B = 0.5 T and B = 0.7 T with the wiggler error of ${\Delta}B/B=0.09%$ at 200 passes and the results were compared to those of without errors. The intensity of the radiation, behavior of the radiation spot size and the variation of the curvature of the phase were highly sensitive to the wiggler error of ${\Delta}B/B$ > 0.09%, but were less sensitive to the wiggler errors for ${\Delta}B/B$ < 0.09% in a free-electron laser (FEL) oscillator based on the proposed FEL facility.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.3
• /
• pp.1319-1326
• /
• 2011

We have investigated the characteristics of the electron beam (e-beam) in the miniaturized free electron laser module by using the commercial 3D simulation tool OPERA. The e-beam was made parallel before entering the slit-type wiggler by the negative bias applied to the central electrode of the electron lens. With respect to the different structures of the wiggler, we obtained the inner distributions of the electrical potential and the electric field, which was, in turn, used to calculate the trajectory of the e-beam in the wiggler.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.12
• /
• pp.1121-1126
• /
• 2014

To compensate location error of ultrasonic horn, the laser scanning system based on the galvanometer scanner is developed. It consists of the 3-Axis linear stage and the 2-Axis galvanometer scanner. To measure surface shape of three-dimensional free form surface, the dynamic focusing unit is adopted, which can maintain consistent focal plane. With combining the linear stage and the galvanometer scanner, the scanning area is enlarged. The scanning CAD system is developed by stage motion teaching and NURBS method. The laser scanning system is tested by marking experiment with the semi-cylindrical sample. Scanning accuracy is investigated by measured laser marked line width with various scanning speed.

• Vacuum Magazine
• /
• v.3 no.4
• /
• pp.4-7
• /
• 2016

An X-ray Free Electron laser facility (PAL-XFEL) has been built in Pohang Accelerator Laboratory to provide X-ray FEL radiations for photon users. The machine consists of a 10 GeV normalconducting S-band linear accelerator and two undulator beamlines. The hard and soft X-ray beamlines will provide FEL radiations with wavelengths of 0.6 to 0.1 nm and 4.5 to 1 nm, respectively. Beam commissioning of PAL-XFEL is ongoing and user service will start in 2017. In this report, the PAL-XFEL layout and the working principle are discussed.

• Proceedings of the KIEE Conference
• /
• 1997.07e
• /
• pp.1861-1863
• /
• 1997

The free electron laser(FEL) with the tapered wiggler in the Compton regime where the space charge effect is negligible was simulated on the basis of one dimensional model. Bunching process and the trajectories of 480 particles, which were loaded randomly in the phase space, were tracked as they traversed the wiggler, and the power and the efficiency of the FEL were estimated.

• Transactions on Electrical and Electronic Materials
• /
• v.1 no.1
• /
• pp.32-39
• /
• 2000

Langmuir probe measurements of electron density, electron temperature and potential are mad in the early stage (<5${\mu}$s) of a laser ablated plasma plume, in which a positive current form positive ions and a electron current are overlapped. The plasma wes produced by focusing the second harmonic, 532 nm, of Q-switched Nd:YAG laser on a high purity carbon target. Then the laser intensity on the target of ~1.6${\times}$10$\^$15/ W/$\textrm{cm}^2$. The measured electron desities and temperatures are ~2${\times}$10/sip 11/ cm$\^$-3/ and -3 eV. In particluar , the phenomenon that the electron temperature decreased and then increased was observed,. It could be well explained that this phenomenon occurred in the process of inverse Bremsstrahlung of free electrons in plasma. Additionally, the plasma potential(>11V) was higher than the published values.

• Journal of the Korean Magnetics Society
• /
• v.21 no.6
• /
• pp.231-236
• /
• 2011

X-ray Free Electron Laser (XFEL) has been known to be a dream X-ray source opening an epoch in X-ray science with the characteristics of femtosecond pulse, perfect transverse coherence, and ultra-high brightness. Here we introduce the XFEL source shortly and report the status of the worldwide XFEL facilities, and then the experimental instrumentations for XFEL are reviewed in their conceptual classification scheme. Scientific examples and applications proposed in the research area of magnetism for XFEL are briefly mentioned. Finally are summarized the facility overview and the scientific proposals for PAL-XFEL project.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1999.10a
• /
• pp.378.2-378
• /
• 1999