An unusually rigorous circuit-theory treatment of a half-bridge SSTC, by Emre Uncuoğlu, Özcan Kalenderli and Hakan Kuntman of Istanbul Technical University (İTÜ), published through the Turkish Chamber of Electrical Engineers (EMO). There is no mains transformer and no spark gap. Two MOSFETs (Q1, Q2) half-bridge the primary directly through a capacitive divider (C1-C4). The design was derived from a transfer-function model of the coil, down to its zero-pole plot, before anything was built. The gate drive is a complementary P/N totem-pole pair (IRF9520/IRF510) feeding a gate-drive transformer. Primary feedback comes from a current transformer, so the drive frequency tracks the coil's own resonance and the tank does not need re-tuning. The results are confirmed on the oscilloscope: 100 V in, 18.5 kV out at 170 kHz resonance. The paper photographs the finished coil and its discharge but never the driver board up close, so no board photo is claimed here. Both circuit diagrams are reproduced instead, from the paper's own figures.
Schematics and photos
power-stage schematic (Şekil 7) 
gate-drive schematic (Şekil 8) 
coil assembly photo (Şekil 11) 
discharge photo (Şekil 12)
Sources
This is the card from the driver tree, written from what the builder published. Send corrections through the forum.