A. Sagara

J. Miyazawa

T. Goto

National Institute for Fusion Science (NIFS-Repository)

    A compact helical reactor named FFHR-c1 has been proposed as a helical type nuclear test machine in the 1stIAEA DEMO Programme Workshop [1]. FFHR-c1 is basically a large duplication of LHD with the scale factor of 10/3, i.e., the helical coil major radius, Rc, of FFHR-c1 is 13.0 m. Two options with different magnetic field strength are under consideration for FFHR-c1. One is named FFHR-c1.0 with Bc = 4 T and the other is FFHR-c1.1 with Bc = 5.6 T, where Bc is the magnetic field strength at Rc, Typical machine parameters of FFHR-c1 are compared with those of LHD and FFHR-d1 [2,3] in Table 1.   To design the core plasma in FFHR-c1 using the Direct Profile Extrapolation (DPE) method [4,5], the effect of additional heating has been taken into consideration. The heating power in the reactor, Preactor, in the DPE method has been modified to  Preactor = Pα – PB + Paux = Caux (Pα – PB),       (1) where Pα, PB, and Paux is the alpha heating power, the Bremsstrahlung loss, and the auxiliary heating power, respectively. In Eq. (1), a factor Caux is introduced to linearize the equation. Note that Paux = (1 – 1/Caux) Preactor.The confinement improvement factor, γDPE, used in the DPE method [5] has been modified to  γDPE* = ((1.0 – 0.35/Caux) / (Pdep/Pdep1)avg,exp)0.6,   (2) where (Pdep/Pdep1)avg,exp is the peaking factor of the heating profile in the experiment. Plasma parameters in FFHR-c1 are estimated by the modified DPE method as shown in Fig. 1. “Q > 7” with Pfusion = 5 Pα ~ 1 GW (Caux ~ 1.8) and “self-ignition” with Pfusion ~ 1.7 GW (Caux = 1) can be achieved in FFHR-c1.0 and c1.1, respectively. 1) http://advprojects.pppl.gov/Roadmapping/IAEADEMO 2) A. Sagara, et al., Fusion Eng. Des. 87 (2012) 594. 3) T. Goto, et al., Plasma Fusion Res. 7 (2012) 2405084. 4) J. Miyazawa, et al., Fusion Eng. Des. 86 (2011) 2879. 5) J. Miyazawa, et al., Nucl. Fusion 52 (2012) 123007. 010203040#115787, t = 3.900 sFFHR-c1.1FFHR-c1.0ne0,reactor010Te0,reactor0510 β0,reactor00.511.55 10CauxPfusionFig. 1. Plasma parameters estimated by the modified DPE method. (a) the central electron density, (b), the central electron temperature, (c) the central beta, and (d) the fusion output, in FFHR-c1.0 (open squares) and c1.1 (closed circles), are plotted with respect to Caux.Table 1. Typical machine parameters in LHD, FFHR-c1.0, FFHR-c1.1, and FFHR-d1. The maximum duration time in FFHR-c1.1 is limited to a half year since the neutron shields is expected to be 5/6 times thinner than in FFHR-d1.  LHD FFHR-c1.0 FFHR-c1.1 FFHR-d1RcHelical coil major radius 3.9 m 13.0 m ← 15.6 mVpPlasma volume ~30 m3 ~1,000 m3 ← ~2,000 m3BcMagnetic field strength at Rc~2.5 T 4.0 T 5.6 T 4.7 T Wmag Magnetic stored energy ~1 GJ ~68 GJ ~126 GJ ~160 GJ Paux (τaux)Auxiliary heating power (heating time)30 MW (2 s) 140 MW (1 year) 50 MW (1 hour) 50 MW (1 hour) Pfusion Fusion output – ~1 GW ~2 GW ~3 GW τdurationMaximum duration time of a shot1 hour 1 year 6 month 1 year ΦnMaximum neutron fluence per shot – ~8 dpa(~0.8 MW/m2 × 1 year) ~8 dpa(~1.5 MW/m2 × 6 month) ~15 dpa(~1.5 MW/m2 × 1 year) 269§7. Core Plasma Design of the Compact  Sub-Ignition Helical Fusion Reactor FFHR-c1Miyazawa, J., Goto, T., Sagara, A.

Core Plasma Design of the Compact Sub-Ignition Helical Fusion Reactor FFHR-c1

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