Formation of Advanced Tokamak Plasmas without the Use of an Ohmic-Heating Solenoid

Abstract

A new operational scenario of advanced tokamak formation was demonstrated in the JT-60U tokamak. This was accomplished by electron cyclotron and lower hybrid waves, neutral beam injection, and the loop voltage supplied by the vertical field and shaping coils. The Ohmic heating (OH) solenoid was not used but a small inboard coil (part of the shaping coil), providing less than 20% of total poloidal flux, was used. The plasma thus obtained had both internal and edge transport barriers, with an energy confinement time of 1.6 times H-mode scaling, a poloidal beta of 3.6, and a normalized beta of 1.6, and a large bootstrap current fraction (>90%). This result opens up a possibility to reduce, and eventually eliminate, the OH solenoid from a tokamak reactor, which will greatly improve its economic competitiveness.

Spherical tokamaks: Present status and role in the development of fusion power

“…(iv) NBCD assisted by bootstrap current using a seed plasma. (v) Inductive drive during a beta ramp, using flux from the vertical field ramp [25,26], a major contribution in an ST.…”

Aspect ratio dependencies of D–3He fueled tokamak reactors

“…However, as the synchrotron radiation loss is reduced due to the lower toroidal field, the power fraction to ion can be reduced to F ion = 0.6 for obtaining the hot ion mode of T i /T e ∼ 1.5 (see column (2) in Table 1). Thus, we have found that the power fraction to ion should be larger than 0.6 in the D- 3 He MT reactor and the operation regime is not so wide as in a ST as will be seen below.…”

“…Recent successful experiments of the plasma current ramp-up by the vertical field and heating power [2,3] encourage parameter studies of D- 3 He spherical tokamak (ST) and medium aspect ratio tokamak (MT) reactors because the large plasma current is necessary for D- 3 He fusion. Additionally, the hot ion mode (T i > T e ) is indispensable to achieve D- 3 He fusion to cope with the synchrotron radiation loss.…”

Impact of an ‘inter linked’ central solenoid configuration on the size of tokamak DEMO

“…On the other hand, the small size of DEMO needs advanced tokamak operation techniques, e.g. a high beta operation to obtain P fus of the order of gigawatt, an advanced non-inductive plasma current ramp-up method [3], and so on. For example, in the design of the compact tokamak fusion DEMO SlimCS, the CS is not used for the plasma ramp-up but for the plasma shape control [4][5][6].…”