H. Tazawa

K. Kawahata

K. Nakayama

K. Tanaka

S. "Okajima

T. Tokuzawa

Y." Ito

National Institute for Fusion Science (NIFS-Repository)

§35. Develoment of 1.2W cw 57-J.tm CH30D Laser Okajima, S., Nakayama, K., Tazawa, H. (Chubu Univ.), Kawahata, K., Tanaka, K., Tokuzawa, T., Ito, Y. A high power 57-1-L m CH30D laser pumped by 9R(8) cw C02 laser has been developed for diagnostics of high-density and large-volume plasmas as in ITER for example. I> The pumping C02 laser is about 3 m in length, and the cavity is formed by a grating (150 lines/mm) and a ZnSe output mirror (55% reflection for 10.6~m) attached on PZT. The output power for each line is shown in Fig.l. The maximtJ.m output power is over 250 W for the 1 OP(20) line. The FIR laser is about 2.9 m in length, and the laser tube diameter is 25 mm. The laser cavity is formed by a plane metal mirror having off-axis input coupling hole (3 mm) and a Si hybrid mirror having an FIR output coupling hole of 14 mm in the center. 300 - 2.50 ~ ex: ~ 200 0 c.. ~ 150 c.. f-::> 0 100 ex: UJ Vl < ..J 50 8 0 9-l 0- 1-L m branch 9R(24) 91'(22) ~R(4) 9R(44 9P(4) I I i~"· 9.0 9.1 92 9.3 9 .4 9 . .5 9.6 9.7 9.M 9.9 10.0 WAVELENGTH I J.Lm) 300r---------------------------------~ l 0-1 I - 1-L Ill branch ex: 2.50 UJ ~ ~ 200 f-::> c.. ~ 150 0 ex: ~ 100 < 10R(26) 10P(20) 10P(4l lOP( 50 ..J 8 50 WOR(4R) 'tR(2 0u':-J.o--~1, ocu.l .I..IJ..UI.Jo..IO • .J.LJ.J.2.uwJ..l.3..J..J..LLAII o-.4.J...J....I.I..LJo..s:..J...Llll o..L6li.l-l.IO.lJ7 Ul.l o..L.•.LLLLJc___J • 10.9 11.0 WAVELENGTH [ J.L m] Fig. I. C02 laser output power. 248 An output window of the laser tube is polyethylene sheet of 1 mm in thickness having 80% transmittance for 57 1-L m wavelength. On the CH30D laser pumped by 9R(8) C02 laser , 57-1-L m and 47-1-L m lines have been observed. But, the two laser lines can be selected easily by using an FIR polarizer, because the polarization of 57-1-L m laser is perpendicular and that of 4 7 -1-L m laser is parallel to that of pumping C02 laser. Addition of He to CH30D and the cooling of the laser tube are effective for the 57-~m laser output (Fig.2). The maximum output power of 1.75W has been obtained for 57- and 47-~m by 150W C02 laser pumping (Fig.3). This power level is estimated 1.2W for 57-J..lm line, and 0.5W for 47-J..lm line. -Cll ·a 1.0 ::s :e 0.8 5 f-. ~ 0.6 f-. ::::::> 0 0.4 ~ B3 0.2 < ......l pump: 9R(8) 105W 0: With He (+0.12torr) 1:::. : No He (0.28torr) 0. 0 L,__....__.l,__...l--_L_-'--..J._-'--_L___.____t___J..__L__L___j 12.0 8.0 6.0 4.0 2.0 0.0 -2.0 LASER WALL TEMPERATURE (''C) Fig.2. Cooling effect of laser tube for 57-11m CH 3 OD Fig.3. laser output power. Total output power for 57- and 47-J-lm CH30D lasers. Reference 1) Okajima, S.,et.al.,Rev. Sci. Instrum.,12..(2001) 1094. 

Develoment of 1.2W cw 57-μm CH3OD Laser

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Develoment of 1.2W cw 57-μm CH3OD Laser

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