Mjollnir I is closer to completion with the secondary coil being the only major component yet to be made. I've recently completed the safety gaps on both the Terry filter and capacitor bank, and have finished making the primary spark gap. In the picture below, you can see each of these parts connected and ready for operation with the magnet wire for the secondary coil in the foreground. Upon completion of the coil, the safety gaps and main spark gap will need to be adjusted for optimal performance. Besides the secondary coil, I still need to construct a strike rail to protect the primary coil, a switch box for ease of operation (right now I'm still plugging and unplugging the coil to operate it), and purchase a fan to quench/cool the spark gap.
The primary spark gap I chose was a multi-gap design based on the Richard Quick multigap. Rather than having two electrodes (making one big spark), I have ten electrodes, which forces the arc to be distributed across nine separate gaps. This improves electrode cooling by distributing the heat over more electrodes, and makes smaller arcs, which can be easily quenched. When the gap arcs, plasma is formed between each electrode, making a highly conductive path for electricity to follow. This creates a connection across the electrodes for longer than is needed to discharge the capacitors. By quenching the gap, the plasma is removed, suppressing the arcs and improving the coil's efficiency. Below you can see the main spark gap in operation (taken without a flash).
In the close up below, the plasma between the copper tube electrodes is clearly visible. When the coil is operating, it is EXTREMELY loud. So loud in fact, that I need ear protection if I'm going to be operating the coil for any length of time. Unfortunately, this means that I run the risk of waking up my roommates or neighbors if I want to work on it at night(which is when I seem to make the most progress). Now for the secondary coil!