Simultaneous Firing at Last, First Pinch above 1 Mega-Amp, Record-High Pressure

Posted by Lerner on May 05, 2010 at 11:06 AM
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This demonstrates that we have the switching problem under control, although we still must replace the fragile nickel trigger electrodes with tungsten ones. 

By increasing our charging voltage to 30 kV, we obtained the first pinch at over 1 Meg-amp. This pinch was achieved with a fill pressure of the deuterium gas of 40 torr, a record, as far as we know, for a DPF.

Switch Synchronicity

On April 26, LPP demonstrated the simultaneous firing of all 12 switches in the FF-1 capacitor bank. 

In the course of the month LPP had installed fiber optic cables on all 12 switches, with optical-electrical converters to convert the optical pluses from the switch firing into electrical signals for the oscilloscopes. We could then tell which switches were firing and which were not. Those that were not were screwed down by several thousandth of an inch, narrowing the gap between the trigger electrode and the charged electrode of the switch.

This method, which we had tested in a preliminary fashion last month, worked.  For four shots, we were able to get all the switches to fire on the trigger, and they all fired with 25 ns of each other.
 
By this time, we were still using the automotive sparkplugs with nickel electrodes.  They were at the end of their lifetime, with two sparkplugs breaking on the last day of testing.

We have now received the new tungsten-rhenium electrodes which we will use to produce our own spark plugs. We now know we can adjust these new spark plugs to fire synchronously. We expect them to have a very long life and, since they will have very smooth surface, to practically eliminate pre-firing.
 

First FF-1 pitch over 1 MA, Record 40 torr pressure

Also on April 26, we were testing the bank at 30 kV, a move up from the 24 kV charging voltage that we have been using for some time.

As expected, the peak current moved up to over 1 MA. What was unexpected was that we had a pinch—a transfer of energy into a plasmoid—at the fill pressure of 40 torr.

We were deliberately using a pressure about twice what we believe is optimal for this charging voltage in order to avoid a pinch and test electrical characteristics of the device.  But the plasma pinched anyway, although well after the higher current had passed.  The 1.03 MA current is a record for us in a pinch, but the 40 torr is a record for any DPF.

Previously the highest operating pressures had been 25 torr at LPP’s own 2001 joint experiments with Texas A and M University and the same pressure in 2004 experiments at the National Institute of Education, Singapore. 

When testing resumes in May, with the new trigger electrodes, we intend to continue firing at over 1 MA, but optimizing the pressure at around 20 torr.  Later in the month we hope to move up to full power, with a charging voltage of 45 kV, where 40 torr will then be near optimum pressure.