Wednesday, December 17, 2008

IEC 2008 - Kyoto

I just received a report on the IEC Fusion 2008 conference from Joel Rogers - one of the participants. This is a report of the conference schedule which has links to the abstracts of the papers presented. You can also see the poster for the conference [pdf] which has a very nice picture of a temple on the Uji-Campus of Kyoto University.
Uji is surrounded by beautiful landscapes centering on the Uji River with more than a thousand years of history. It is abundant with historical assets including Byodoin Temple and Ujigami Shrine, both of which are registerd in the UNESCO world heritage list. A lot of historical assets and autumn tints in early December attract many visitors to Uji.

The Byodoin Temple was first a villa owned by Fujiwara Michinaga, the model for the hero Genji in the Tale of Genji. Then in 1052 it was converted into a temple by his son. The central hall in the above photo is popularly known as Hoohdo (Phoenix Hall), an image of which is found on 10-yen coins.
Here is the abstract of the talk [pdf] Dr. Rogers gave.
IEC Polywell[2] is a candidate for commercial power generation. Particle-in-cell simulation was used to follow the time sequence of plasma development starting from neutral deuterium gas in a cubic Polywell. The left figure below shows electrons flowing in and out of the core along 8 cusp lines. The 8 rectangles are 1.0kG coil-magnets separated by 30cm (inside core diameter) and biased to 15kV. Electron guns (5A) are centered on the 4 vacuum tank walls, held at 0V. The center figure shows the ion distribution at Beta ≅ 1 density. Bounded by a 2cm thick shell, the interior ion population is uniform inside the shell. The shell is composed of ions that have slowed prior to reflecting at the edge of the potential well. The right figure shows the ion velocity (U) population. The flat top indicates uniform inside magnitude, |U| = 1.3x10E6m/s (18keV). The fusion rate was computed as n2·<σ(v)·v>·a3/2, where n is the ion density (n=1.1x10E11/cm3), σ is the parameterized DD fusion cross section, v is the ions’ relative velocity, and a is the diameter(20cm) of the ~cubic volume inside which the velocity is uniform. Substituting the simulated n, v, and a, resulted in a fusion rate prediction of 9x107 fusions/s, in fair agreement with Bussard's measured WB-6 neutron rate[2]. The simulation predicts the following features of Polywell: (1) Electrons circulate out and in freely along cusp lines. Very few electrons hit the magnets. (2) Ions are trapped in an electrostatic potential well, which maintains a steady state, spatially uniform, monoenergetic ion population long enough for substantial fusion to occur.
(3) The surface density of trapped electrons corresponds to a Beta value on the order of unity.

Particles reaching the tank wall will generate electricity efficiently while particles hitting the magnets will generate electricity less efficiently. The effective power gain factor (Q) can be estimated as the ratio of fusion power output to the portion of electric power input spent to replace ions hitting the magnet boxes. Simulated Q-factor as a function of device size has predicted the size of a steady state, break-even (Q=1) device which needs to be tested.
The pictures mentioned are included in the pdf.

No comments: