20
2 Discharges in Current Large Tokamaks
2.2 Discharges of Current Large Tokamaks
Figure 2.1 is a photograph of the inside of TEXTOR, a limiter tokamak [1], which
was built for intensive studies of PSI, together with the picture of discharged plasma
in it. As seen in the figure, visible radiation from the plasma center is far less
than that from boundary plasma and limiters. Because plasma temperature is high
enough to fully ionize hydrogen, giving no emissions like the Balmer and the Lyman
series but the Bremsstrahlung which is invisible. The Balmer series emissions from
excited hydrogen atom largely contribute to radiation from boundary plasma. In addition, stronger radiation appears from the surface of the main limiter owing to their
temperature rise by plasma power load.
TXTOR
(a)
(b)
(c)
(d)
Fig. 2.1 Discharges in TEXTOR a inside of TEXTOR and b a discharge limited by ALT-II belt
limiter, c a discharge limited with main limiters made of W-coated graphite at the bottom and top
as shown in d with shiny one before and dark after use. During the discharge, the surface of the
ALT-II belt limiter gave strong radiation owing to plasma heating
2 Discharges in Current Large Tokamaks
2.2 Discharges of Current Large Tokamaks
Figure 2.1 is a photograph of the inside of TEXTOR, a limiter tokamak [1], which
was built for intensive studies of PSI, together with the picture of discharged plasma
in it. As seen in the figure, visible radiation from the plasma center is far less
than that from boundary plasma and limiters. Because plasma temperature is high
enough to fully ionize hydrogen, giving no emissions like the Balmer and the Lyman
series but the Bremsstrahlung which is invisible. The Balmer series emissions from
excited hydrogen atom largely contribute to radiation from boundary plasma. In addition, stronger radiation appears from the surface of the main limiter owing to their
temperature rise by plasma power load.
TXTOR
(a)
(b)
(c)
(d)
Fig. 2.1 Discharges in TEXTOR a inside of TEXTOR and b a discharge limited by ALT-II belt
limiter, c a discharge limited with main limiters made of W-coated graphite at the bottom and top
as shown in d with shiny one before and dark after use. During the discharge, the surface of the
ALT-II belt limiter gave strong radiation owing to plasma heating