1 - Nuclear Sciences and Applications - IAEA

606 FUJII et al.
1. INTRODUCTION
Second harmonic ICRF heating experiments have been carried out at 120 and
131 MHz on JT-60 in outer and lower x-point divertor and limiter configurations.
The peak position of the k| spectrum launched by a 2 X 2 loop antenna [1] can be
changed from 0 m" 1 to 10 m" 1 with the phasing mode from (0,0) to (TT,O), where the
figure in the former parentheses is the toroidal phase difference and the figure in the
latter is the poloidal difference. The ICRF power has been increased up to 3.0 MW
in the (0,0) mode because of the large coupling resistance of about 5 U [2]. The
power density of the antenna reached 1.6 kW-cm" 2 . Two heating regimes of pure
hydrogen 2cocH and H-minority (He(H2))2wcH have been investigated up to 3 MW
for Ip = 1-2 MA and n,. = (1.3-3.5) X 10 l9 m" 3 . Intense NBI and on-axis ICRF
have been combined at NBI powers of 10-20 MW and ICRF powers of 0.7-2.2 MW
in order to achieve efficient central heating. Initial combination of ICRF and pellet
injection has been carried out.
2. HEATING PROPERTIES OF SECOND HARMONIC ICRF HEATING
Two heating regimes of pure hydrogen 2o)cH and H-minority 2wcH have been
investigated.'Figure 1 shows a typical result for 2wcH in the (0,0) mode at Ip =
1.5 MA. When an ICRF power of 2.9 MW was applied, the plasma stored energy
W DIA and the electron density H,, increased. The increment of the stored energy was
0.38 MJ. The ion temperature rise, ATf*, from a charge exchange neutral measurement,
was about 1.1 keV, and the ion temperature, Tj AB , from the Rutherford scattering
method and the electron temperature, Tj s , from the Thomson scattering
method, were 3.4 and 3.8 keV, respectively. An ion tail, which was accelerated up
to 100 keV, was observed during the ICRF pulse.
He(H2)2