Use of electronic space charge to accelerate, focus and bunch plasma ions for pellet fusion

Prior experiments have shown that deep, nearly parabolic, potential wells can be created by the injection of electrons into a spherical diode. Furthermore, it has been demonstrated that a large fraction of the input power can be transferred from the electronic space charge to ion motion provided the electron collection probability is small. However, the instantaneous power required for pellet fusion is still beyond the capabilities of existing machines. By utilizing the spherically symmetric potential wells found previously, the instantaneous power delivered to a small target at the center can be magnified (or bunched) by factors of 10-100. The measurement of these potentials, the comparison with a realistic theory, and an extrapolation to higher voltages/energies will be presented. Recent experiments are described which imply that bunching is present in a planar diode. Although the experiments were performed at low voltages (kV), the extrapolation with constant perveance is straight-forward.