443 research outputs found
On the failure of neutron yield scaling in the Dense Plasma Focus
The observed scaling of neutron yield in the Dense Plasma Focus (DPF) as the
fourth power of the current in the plasma was the principal driver of the
growth of DPF research in its early days. Subsequent discovery of failure of
this scaling law was also the principal reason for its abandonment by major
laboratories. Attempts to understand this failure of scaling have so far been
inconclusive. This letter looks at this failure in the context of the recently
introduced Generalized Plasma Focus (GPF) problem and suggests a possible
reason that can be experimentally examined using small plasma focus devices.
This involves restrictions placed on the drive parameter by conservation laws
for mass, momentum and energy. A suggested empirical workaround to the problem
of neutron yield scaling failure could also be configured as a method for
increasing the pressure range for neutron emission in small DPF devices.Comment: Accepted for publication in Physics of Plasmas on 14th July 202
Electronic Structure and Bulk Spin Valve Behavior in CaRuO
We report density functional calculations of the magnetic properties and
Fermiology of CaRuO. The ground state consists of ferromagnetic
bilayers, stacked antiferromagnetically. The bilayers are almost but not
exactly half-metallic. In the ferromagnetic state opposite spin polarizations
are found for in-plane and out-of-plane transport. Relatively high out of plane
conductivity is found for the majority spin, which is relatively weakly
conductive in-plane. In the ground state in-plane quantities are essentially
the same, but the out of plane transport is strongly reduced.Comment: 5 page
On the construction of a local curvilinear coordinate system conforming to the native curved geometry of the plasma focus sheath
This paper describes in detail the construction of a local right-handed,
orthogonal curvilinear coordinate system whose axes are along the local
tangent, the local azimuth and the local normal of an analytically defined 3D
surface of rotation, whose shape mimics the shape of a plasma focus current
sheath. Expressions for various differential operators are derived in a
tutorial format for the benefit of young researchers and non-specialists.
Physical problems expressed in this coordinate system would benefit from the
natural symmetry properties of the plasma focus sheath. For example, the normal
component of current density is zero and the velocity has mainly the normal
component. This paper is meant to serve as a readily available reference in the
hope that it would be found useful
- β¦