AAWSAP DIRD, Inertial Electrostatic Confinement Fusion, March 2010

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There are several advantages of the dipole-assisted IEC. By applying the desired
voltage to the cathode grid, high-energy ions are easily obtained, hence plasma heating
is straightforward. Indeed in this case fusion is dominated by beam-beam (non­
Maxwellian reactions). Also, the dipole magnet at the center of the device produces
field lines that trap ions and compresses them within the inner radius of the dipole.
Thus, a very high ion density can be achieved leading to high reaction rates via beam­
beam fusion. Biasing the dipole magnet to the same potential as the cathode grid
solves the problem of space charge build-up due to the high ion density at the center of
DaIEC.
DAIEC EXPERIMENTS
The purpose of current experiments is to investigate the focusing effect of a dipole
magnetic field in a spherical IEC. In particular, the primary goal is to measure the
increase in plasma densities achieved by a dipole-assisted IEC. In theory, the
introduction of a current ring or dipole coil into the base configuration would focus
particles into the center of the dipole, increasing the plasma density at the core of the
device. A schematic of the current experimental setup is shown in Figure 3.5.
Figure 3.5. (a) Dipole Magnetic Field and (b) Layout of Devices
This experiment employs two split spherical grids as shown in Figure 3.5. Ions are
created in the discharge between these grids and the vessel wall. They are extracted
and accelerated by the grid potential so they pass through the dipole field of Figure
3.5a . Experiments have confirmed that an order of magnitude density increase (vs. no
dipole present) can be achieved in the center region. A double Langmuir probe is
inserted at various positions throughout the center region.
The use of a bias on the dipole magnet structure to control space charge bui ld-up was
also studied. In an ion-injected IEC partial space-charge neutralization at the core
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