[en] A new idea to produce the distribution function similar to that of alpha-particles in an ignited plasma has been proposed. This concept is attributed to the acceleration of the injected beam up to about 1 MeV/nucleon by the ICRF wave with cyclotron higher harmonics. This new method makes it possible to perform the simulation experiments for alpha-particles under the condition of moderate plasma parameters (e.g., Tsub(e) = 4 keV, nsub(e) = 3.5x10¹⁹m^-3 and B sub(T) = 3 T). And it is found that 3ωsub(ci) ICRF wave is preferable compared with other cyclotron harmonics, from the viewpoints of the effective tail formation with smaller bulk ion heating and lower amplitude of the applied electric field. The formula for the maximum energy of the extended beam is also derived. (author)

[en] Interrelationships between the binding by rabbit muscle phosphofructokinase of citrate, ATP, GTP, and adenyl-5'-yl imidodiphosphate (AMP-PNP) were investigated. To allow measurements at 25 degrees C, pyruvate kinase and phosphoenolpyruvate were included in the dialysis media to rephosphorylate ADP formed by the weak ATPase action of phosphofructokinase. Binding of citrate was enhanced by GTP nearly as much as by ATP, although GTP does not inhibit the catalytic activity of the enzyme. The results are consistent with the interpretation that binding of GTP, and, by analogy, ATP, at the catalytic site enhances the binding of citrate. AMP-PNP also enhanced citrate binding. Both ATP and GTP appear to bind at three sites per enzyme subunit, with the apparent third site binding relatively weakly. The estimated dissociation constants for the first two sites, about 33 microM for both for ATP compared with 3 and 280 microM for GTP, are consistent with kinetic results that imply lack of effective competition by GTP for the inhibitory site. When a compound binds at two or more sites on a macromolecule, the position and shape of the binding curve are sensitive to the geometric mean of the binding constants but quite insensitive to the magnitudes of the individual constants; thus, binding affinities cannot be estimated with confidence in such cases

[en] Beam driven steady state tokamaks of moderate size (R_o = 4.55 m) is analyzed by a full consistent beam current drive analysis code, which consistently includes MHD equilibrium, kink and ballooning stability analysis, bootstrap current, power balance and momentum balance calculations. It was found that this moderate size is sufficient to demonstrate the feasibility of steady state operation by the neutral beam current drive. The maximum Q value attains Q = 7∼9 with the fusion power P_f = 500∼800 MW and L-mode confinement is sufficient to sustain self consistent equilibria. The Q value is nearly doubled due to the bootstrap current and the T_i > T_e feature of beam driven tokamaks. The optimum beam energy is 1.0∼1.2 MeV and the toroidal rotation effects has been negligible. (author)

[en] A new MHD-equilibrium/current-drive analysis code was developed to analyse the high beta tokamak equilibria consistent with the beam driven current profiles. In this new code, the critical beta equilibrium, which is stable against the ballooning mode, the kink mode and the Mercier mode, is determined first using MHD equilibrium and stability analysis codes (EQLAUS/ERATO). Then, the current drive parameters and the plasma parameters, required to sustain this critical beta equilibrium, are determined by iterative calculations. The beam driven current profiles are evaluated by the Fokker-Planck calculations on individual flux surfaces, where the toroidal effects on the beam ion and plasma electron trajectories are considered. The pressure calculation takes into account the beam ion and fast alpha components. A peculiarity of our new method is that the obtained solution is not only consistent with the MHD equilibrium but also consistent with the critical beta limit conditions, in the current profile and the pressure profile. Using this new method, β ∼ 21 % bean and β ∼ 6 % D-type critical beta equilibria were scanned for various parameters; the major radius, magnetic field, temperature, injection energy, etc. It was found that the achievable Q value for the bean type was always about 30 % larger than for the D-type cases, where Q = fusion power/beam power. With strong beanness, Q ∼ 6 for DEMO type tokamaks (∼500 MWth) and Q ∼ 20 for power reactor size (4.5 GWth) are achievable. On the other hand, the Q value would not exceed sixteen for the D-type machines. (author)

No abstract available

[en] The longitudinal momentum distributions of core fragment from one nucleon removal reaction were calculated taking into account the core absorption effect within the Glauber multiple scattering model. The (¹¹Be, ¹⁰Be), (⁸B, ⁷Be), and (¹⁹C, ¹⁸C) reaction on the light target are taken as typical examples of the s, p, and d orbitals of last nucleon. The core absorption effect depends on the angular orbital of the last nucleon. Taking into account this effect we obtained the following results on the each reaction. The first, there is almostly no effect on the ¹¹Be case. The second, we can consistently understand the narrow width of ⁷Be fragment with spatial extent like the normal p-shell nuclei of ⁸B. The third, our calculated result shows that the s-state is dominant component in the ground state of ¹⁹C. (author)

[en] We measured the neutronic performance of a mixed moderator of polyethylene particles plus liquid hydrogen as the first test of a mixed type moderator. The energy spectrum from the mixed moderator looks like a linear combination of each spectrum from the polyethylene particles and from liquid hydrogen. We obtained 1.2~1.4 times higher cold neutron intensity, but with a longer pulse width than a decoupled liquid hydrogen moderator in the cold neutron region. In the slowing-down region it gave much higher intensity with almost the same pulse width. We found that this type of moderator exhibits better characteristics as a narrow pulse thermal neutron source.

[en] The stability of a reactor system with multiple transport lags and a nonlinear control element is analyzed by using the parameter plane method in which variables are transformed into a logarithmic function. Taking lag time as the continuously variable parameter, stability analyses have been conducted for both simplified and realistic reactor models. From the former, many interesting phenomena are observed. For example, under some conditions, the system repeats the periodic sequence of stability and instability with the increment of lag time, while the frequency of a limit cycle changes discontinuously at specific lag time. In the latter model, similar phenomena are observed. 7 refs

[en] In the JIPP T-IIU tokamak, a high power ICRF heating experiment has been conducted up to an extremely high power density (∼2MW/m³) with a total rf power of P_rf = 2MW. Much attention has been paid initially to the problem of impurities, and it has been found that a) the adoption of low-Z materials for the limiter, b) in situ carbon coating (i.e., carbonization) and c) adequate gas-puffing synchronized to the rf pulse are very effective in suppressing radiation loss. In combination with these methods, a remarkable reduction in metal impurities (especially in iron impurity) has been achieved, suppressing the total radiation loss to less than 30∼40 % of the input power. In these reduced-radiation-loss plasmas, characteristics of ICRF-heated plasmas have been intensively studied. With an increase in the ICRF heating power, the deterioration of the energy confinement time has been observed, indicating quantitative agreement with Kaye-Goldston L-mode scaling. It is shown that the so-called profile consistency, which is the leading feature in NBI-heated plasmas, holds also in the ICRF-heated plasma. It has been observed that the electron temperature profile responds only to the safety factor q(a). (J.P.N.)

[en] IN ICRF heating experiments the deposition profile in electrons has been derived experimentally, and comparison with theory has been performed. It is found that the deposition profile is relatively broad (P_rf,e(r) = P_rf,e(0)(1-(r/a)²)^k with k = 1.8), and this is interpreted in terms of characteristics of the mode-converted Ion Bernstein Wave. The distribution of the rf power to each species (electrons, hydrogen and deuterium ions) is in good agreement with theoretical predictions. With the deposition profile experimentally obtained, the electron thermal diffusivity x_e has been calculated, resulting in x_e ∼0.65 m²/s at n-bar_e = 9 x 10¹⁹ m^-3. (author)