Reply To: What can we do with $189 Billion?

[asymmetric_implosion]

markus7 wrote:
Solutions that could be investigated include:

Highest priority – New instrumentation applicable to both 1) the LPP fusor for continuously diagnosing asymmetry problems (sensors for the current and arrival time of each of the sixteen arc filaments and perhaps new sensors for the pinch region?) and 2) critical to the ‘dummy’ fusor test effort, sensors to serve as the ‘goodness’ indicators of testing in the absence of neutron production.

Secondary priorities –
Whatever people can think of
Big geometry variations

1) Wow! This is no small task.

The plasma sheet in most plasma focus devices, if monitored, uses either optical techniques or magnetic probes. The magnetic probes provide information current locally but they are subject to plasma shielding. If a moderate conductivity plasma is generated over the surface of the probes which commonly happens in even ~100 kA devices, the probes need to be corrected for magnetic shielding effects. The key is you have to know the conductivity of the plasma and its thickness. Neither is trivial. The optical emission techniques provide some data on plasma sheet asymmetry but the current or current density is not easy to derive. This is a significant problem that faces many high current plasma devices and people are working on the problem, but it is a very difficult problem.
You can forget about putting diagnostics in the pinch region. They typically screw up the pinch or get badly damaged on the first shot. Emission techniques or laser probing techniques seem to be the only option.

2) Smaller plasma focus devices of the ~300 kA level are reasonably common world wide. Nanyang Technical University in Singapore has two such devices. Kansas State University has a device. A couple companies in the US are using these devices as well. NSTech at the 2 MA level and Alameda Applied Sciences at the ~300 kA level. LLNL also has a ~200 kA device. So the test bed could be available if someone can spark and interest in any of these places. The common diagnostic choices for non-neutron producing reactions would be ion spectrometers which could detect alpha particles from p-11B reactions. They are simple devices in principle but they require alignment using an known ion source. Some papers exist on how to do it but you need a particle accelerator in most cases as the ion source. Other techniques would be nuclear activation using alpha particles as the source. I can imaging building a target that is activated by p-11B alpha particles. I would choose a beta emitter and use a scintillator to count the beta particles as they are produced. In small devices the yield is likely to be extremely low so counts could be a problem, but it might be interesting. My guess would be a money problem. People have specific funded program or internal goals and funding would be required to develop the diagnostic and complete the tests. I would guess ~$50K to develop a single unit activation system for alpha particles and calibrate it to yield. Scientists are expensive.