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Volume 26, Issue 5
Displaying 1-12 of 12 articles from this issue
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Koshi ITAKA1998 Volume 26 Issue 5 Pages 347
Published: May 15, 1998
Released on J-STAGE: August 25, 2010
JOURNAL FREE ACCESSDownload PDF (139K) -
Chiyoe YAMANAKA1998 Volume 26 Issue 5 Pages 348-349
Published: May 15, 1998
Released on J-STAGE: August 25, 2010
JOURNAL FREE ACCESSDownload PDF (446K) -
Toshihiro TAGUCHI, Kunioki MIMA1998 Volume 26 Issue 5 Pages 350-355
Published: May 15, 1998
Released on J-STAGE: August 25, 2010
JOURNAL FREE ACCESSBasic amplification mechanism of free electron laser (FEL) is explained and small signal gain of Compton regime FEL and growth rate of Raman and High gain Compton regime FEL are shown. FELs, which do not use magnetic wiggler, such as Smith-Purcell FEL or Cherenkov FEL are also explained. We also briefly review about startup and slippage which take place in short wavelength FELs using short micro-pulse electron beam.View full abstractDownload PDF (1157K) -
Kazuo IMASAKI1998 Volume 26 Issue 5 Pages 356-361
Published: May 15, 1998
Released on J-STAGE: August 25, 2010
JOURNAL FREE ACCESSThis article describes the status and prospect of free electron laser (FEL). We discuss the feasibility of ASE (Amplified Spontaneous Emission) for short wavelength and reduction of photon cost of FEL. The most important future of FEL, today, is to extend the wavelength toward shorter range less than 150 nm and toward longer range around THz.View full abstractDownload PDF (1170K) -
Akio NAGAI, Kazuo IMASAKI1998 Volume 26 Issue 5 Pages 362-368
Published: May 15, 1998
Released on J-STAGE: August 25, 2010
JOURNAL FREE ACCESSApplications of Free Electron Laser (FEL) performed in Japan are reviewed. The applications are concerning the quantum well, material processing, medical treatment, isotope separation and so on. The prospects of future application of FEL to high gradient accelerator, energy transport, nuclear transmutation are described.View full abstractDownload PDF (1587K) -
Kunio AWAZU, Akio NAGAI, Katsuo AIZAWA1998 Volume 26 Issue 5 Pages 369-373
Published: May 15, 1998
Released on J-STAGE: August 25, 2010
JOURNAL FREE ACCESSInfrared Free Electron Lasers (FEL) application for selectively removal of targeted biomolecules is described. In advanced atherom atherosclerosis, a large amount of lipids, particularly cholesterol esters, accumulates on the arterial wall. The selective removal of cholesterol esters has clinical significance. In the present work we investigate the removal of cholesterol esters by using FELs in an arteriosclerotic region. Thin films of cholesteryl oleate and albumin, and the cross section of a rabbit artery were placed on a microscope and the changes caused by the FEL irradiation of 5.75μm and 6.1μm with 1.5-3 mW were monitored. FEL irradiation at a wavelength of 5.75μm, which is a stretching bibrational mode of the ester, was able to ablate cholesterol esters without affecting albumin and that it can also remove cholesterol esters from rabbits' arterial walls.View full abstractDownload PDF (1585K) -
Tsuneo MITSUYU1998 Volume 26 Issue 5 Pages 374-378
Published: May 15, 1998
Released on J-STAGE: August 25, 2010
JOURNAL FREE ACCESSAs applications of a mid-infrared free electron laser (FEL) to semiconductor research, heterojunction interface analysis, evaluation of ultrafast optical switches using quantum wells, and laser annealing of SiC have been investigated. Band discontinuities at a variety of heterojunctions have been determined precisely using FEL internal photo-emission spectroscopy. Ultrafast all-optical switching has been confirmed for the quantum well devices employing picosecond pulses from the FEL. N-ion-implanted SiC has been successfully annealed in terms of crystallinity and electrical property by irradiation of FEL at wavelengths corresponding to Si-C stretching mode and local vibration mode of implanted N atoms, respectively.View full abstractDownload PDF (918K) -
Nobuhisa OHIGASHI, Yoshiaki TSUNAWAKI, Masayuki FUJITA, Kazuo IMASAKI, ...1998 Volume 26 Issue 5 Pages 379-385
Published: May 15, 1998
Released on J-STAGE: August 25, 2010
JOURNAL FREE ACCESSMagnetic field of a core type wiggler becomes obviously weaker with the decrease of its period due to increasing leakage field. Comparison of a core type helical wiggler with a planar wiggler suggests that the former has leakage field much smaller than the latter wiggler . It urged for us to develop two kinds of helical microwiggler aimed at following two points: (A) the period as short as possible, and (B) the structure ascompact as possible. The former was realized by three poles per period type electromagnetic structure . A peak field of 3.0 kG on axis was achieved with a period of 7.9 mm and gap length of 4.6 mm. The latter was studied by numerical simulation and a helical microwiggler with four poles per period was designed . It will give a wiggler field of 3.7 kG for the period of 10 mm and the gap length of 5 mm. If it is assumed that the K parameter of a wiggler needs 0.2 for FEL oscillation, its period becomes 8 mm for gap length of 5 mm or gap length is enlarged to 7 mm for the period of 10 mm.View full abstractDownload PDF (1490K) -
Yoshiaki TSUNAWAKI, Mie NOGUCHI, Nobuhisa OHIGASHI, Masayuki FUJITA, K ...1998 Volume 26 Issue 5 Pages 386-389
Published: May 15, 1998
Released on J-STAGE: August 25, 2010
JOURNAL FREE ACCESSIn order to get a short wavelength free electron laser (FEL), higher harmonic gain has been analyzed for an FEL using a hybrid planar wiggler with a period of 20 mm. This type wiggler consisting of ferromagnetics and permanent magnets is most convenient and gives the strong field including some higher harmonic components by selecting proper sizes of these magnetic materials. A certain modification of magnetic field distribution is accomplished by small gap length of the wiggler and small width of permendur as a ferromagnet. Gain analysis of FEL shows that higher harmonic gains exceed that of the fundamental for a very high magnetic field and suggests that for high wiggler field of K>1-1.6, higher harmonic gains are improved primarily dUe to its strong field and for low wiggler field of K<1-1.6, gain improvements are mainly due to the modification of the wiggler field distribution.View full abstractDownload PDF (702K) -
Yoshiko TOKURA, Yoshiaki TSUNAWAKI, Mitsuhiro KUSABA, Nobuhisa OHIGASH ...1998 Volume 26 Issue 5 Pages 390-394
Published: May 15, 1998
Released on J-STAGE: August 25, 2010
JOURNAL FREE ACCESSWe have started to develop a tungsten (W) field emission cathode for Cherenkov free electron laser (FEL) or Smith-Percell FEL. In this work, elementary properties of electron beam current from W tip have been investigated by numerical simulation and experiment using a system consisting of W tip, 1 st- and 2nd- gate, and anode. When there was no 2nd gate, the current increased up to-20μA with the absolute voltage of cathode according to the Fowler-Nordheim equation. The addition of 2nd gate decreased the current half to 5th lower than expected value from the simulation. However, it focused and enlarged the current of the electron beam in a certain voltage range of 2nd gate. These phenomena agreed qualitatively with those of the simulation. In further study, improved experiment will be made to get higher current and parallel smaller size of an electron beam.View full abstractDownload PDF (910K) -
Masayuki FUJITA, Koichi OHKUBO, Jizhong CHEN, Hiroyuki FURUKAWA, Kazuo ...1998 Volume 26 Issue 5 Pages 395-399
Published: May 15, 1998
Released on J-STAGE: August 25, 2010
JOURNAL FREE ACCESSBy modulating the laser beam profile in space and time, the photocathode RF gun enables us to control the electron beam in space, time and also energy. We have numerically investigated the generation and acceleration of the energy-modulated electron bunch in the RF linac system. Adjusting the input laser beam profile and the acceleration phase, possibility of producing the 9 MeV electron bunch with energy modulation was demonstrated by the simulation code LUNA. The energy-modulated electron beam can be used to enhance the efficiency of the free electron lasers (FELs) with the optical klystron. Especially, the single-pass FELs in VUV region, which rely on the scheme of the self-amplified spontaneous emission, have benefit in shortening the wiggler length.View full abstractDownload PDF (870K) -
Yasukuni SHIBATA, Chikao NAGASAWA, Makoto ABO1998 Volume 26 Issue 5 Pages 400-403
Published: May 15, 1998
Released on J-STAGE: August 25, 2010
JOURNAL FREE ACCESSThis paper proposes a new method for the ΔK lidar for atmospheric temperature measurement. The principle of the temperature measurement consists of Bragg diffraction of the laser beam by an acoustic wave and the temperature dependence of the speed of sound. As the acoustic frequency that satisfies the Bragg condition with one laser frequency is approximately THz order, the ΔK lidar usually uses differential frequency of two laser systems. In this paper, we plume making use of longitudinal modc spacing generated from only one laser oscillator instead of the differential frequency generated from two single-mode laser oscillators. This method can reduce the influence of frequency instability between two single-mode laser frequencies and the ΔK lidar system is simplified. We successfully conducted temperature-measurement experiments for the ΔK lidar system with the longitudinal multi-mode spectrum of a He-Ne laser in a cylindrical tube and in open space.View full abstractDownload PDF (658K)
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