Experiments with Supersonic Beams as a Source of Cold Atoms

258V
1MΩ
TTL
2.2mF
50Ω
TTL 5V
5V
.1μF
feedback
controller
6.8μH
N Channels
Figure 4.23: A schematic of the coil driver circuit used to drive the 64 stage coilgun
coils. Similar to the driver used in the proof-of-principle experiment, the coils are
switched by two solid-state switches, a thyristor and an IGBT. The elements inside
the dashed box are unique to each coil, while those outside the box are shared by
multiple coil channels.
4.5.2 64 Stage Electronics and Coil Switching
In addition to a new coil design, the electronics used to switch the coils are
improved from the proof-of-principle experiment. Many aspects of the original circuit
remain in place, and some elements are completely unchanged from the circuit used
to drive the coils of the 18 stage coilgun. Those elements which are not changed
are simply noted as such, and the information on these components can be found in
section 4.4.3.
A schematic of the coil driving circuit is shown in figure 4.23 and a photography
of the circuit is shown in figure 4.24. The capacitor that discharges across the coils is
upgraded to a 2.2 mF capacitor, however the power supply and capacitor discharge
resistor remain unchanged. The concept of using thyristors as slow switches to isolate
individual coil channels from each other, and to use fast IGBTs to switch the current
94
4Ω
2μF