Prometheus Fusion Perfection

Fabricated the second row of capacitors. I have one capacitor left…so we can take it to 11 when the time comes!

Also received the capacitor clamps to make mounting easy:

And finally got 2A fuses for the power supply:

In other news, I got Windows XP running on my macbook on a separate partition. Also got LabView installed. More on that later.

I successfully fired the coil power supply’s SCR today. Here’s how: I started by grounding the chassis:

Later inspection revealed less then fantasic electrical conductance between the ground cable and the aluminum chassis.

Wired up the SCR and polywell coils:

For the triggering circuit I improvised with available parts. I settled on this circuit:

Looks like this:

I tested it out and it works!

When the SCR discharges you can see the coils flex and hear a sound from the SCR… and the voltage across the capacitors drops sharply. I took it up to 400V with 5 caps.

Pretty major step forward for the coil power supply.

Nest steps include:

Making a front panel with master power switch, AC indicator, capacitor  bleed switch, high voltage LED indicator.

On the back panel: IEC C14 AC connector, screw down terminals for coils power out, and D-sub interface for computer control (via DAQ). I want to computer control the AC power, bleed resistor and SCR triggering.

Stuart made a keen observation about a relay on the DC side: Relays have a much lower voltage rating for DC vs. AC. So a relay rated at 240VAC may only be rated at 30VDC. This is because DC sparks are harder to quench-  they don’t naturally drop to 0V like AC does. So long story short – I’m going to put the relay on the AC side of the transformer.

I also want to fuse the AC and DC sides.

I mounted the sheet aluminum on the 80/20 chassis:

And installed the new ground cable:

I cut the bus bar to length, and clamped two bars together to get good hole alignment. Then measured and center tapped:

Drilled and mounted:

Wire it up for a test charge. This time we are charging through a 1KΩ 50W resistor network. Everything seems to work as expected.

Wired up the protection diode:

Excellent day in the lab.

I got the elevator key copied, so I’ll never get locked out of the lab. I did a successful test of the mechanical relay.

I rearranged the equipment rack to make room for the coil power supply:

Using 80/20 I constructed a 4U rack mountable chassis for the coil power supply:

Next I mounted the electrical hardware on the sheet aluminum. I started by using a transfer punch to make guides for the drilling. Then I drilled and tapped the holes for M3 bolts:

The first circuit I wired up was the 2 KΩ bleed resistor. Here you can see the bleed resistor wired to the capacitor via a switch. Turning ON the switch bleeds the capacitor:

Next I wired the DC side to the capacitor while minding polarity. Put a voltage meter across the capacitor:

Using the variac I slowly brought up the capacitor to 300V:

Once the capacitor is charged… it holds its charge without much dissipation after the variac goes off.

I was planning to power the relay using this ATX power supply (24V across +12V and -12V):

But during my initial testing it started squeeling and soon blew its fuse!

There was no short circuit that I could see, so perhaps it just died of natural causes?

Anyway… it reminds me: I should fuse the  coil power supply before I go much further!