Index of content:
Volume 80, Issue 3, March 2009
- ELECTRONICS; ELECTROMAGNETIC TECHNOLOGY; MICROWAVES
80(2009); http://dx.doi.org/10.1063/1.3089827View Description Hide Description
The rotary joint is a useful microwave component that connects a fixed part to a rotatable part. This study systematically analyzes the effect of the discontinuity on the interface of a rotary joint for several waveguide modes. Simulation results indicate that the transmission of the mode is independent of the geometry of the joint, and thus is ideal for such application. A rotary joint consisting of two identical mode converters, clasped each other by a bearing, is designed, fabricated, and tested. Back-to-back transmission measurements exhibit an excellent agreement to the results of computer simulations. The measured optimum transmission is 97% with a 3 dB bandwidth of 8.5 GHz, centered at 35.0 GHz. The cold measurement shows that the results are independent of the angle of rotation. In addition, a high-power experiment is conducted. The just developed rotary joint can operate up to a peak input power of 210 W with a duty of 18%. The working principle, although demonstrated in the millimeter-wave region, can be applied up to the terahertz region where the joint gap is generally critical except for the operating mode.
80(2009); http://dx.doi.org/10.1063/1.3095686View Description Hide Description
A thyristor stack for pulsed inductive plasma generation has been developed and tested. The stack design includes a free wheeling diode assembly for current reversal. Triggering of the device is achieved by a high side biased, self supplied gate driver unit using gating energy derived from a local snubber network. The structure guarantees a hard firing gate pulse for the required high application. A single fiber optic command is needed to achieve a simultaneous turn on of the thyristors. The stack assembly is used for switching a series resonant circuit with a ringing frequency of 30 kHz. In the prototype pulsed power system described here an inductive discharge has been generated with a pulse duration of and a pulse energy of 50 J. A maximum power transfer efficiency of 84% and a peak power of 480 kW inside the discharge were achieved. System tests were performed with a purely inductive load and an inductively generated plasma acting as a load through transformer action at a voltage level of 4.1 kV, a peak current of 5 kA, and a current switching rate of .
80(2009); http://dx.doi.org/10.1063/1.3103574View Description Hide Description
We performed an electrical characterization of a tuning fork crystal oscillator using a dual-phase lock-in amplifier. Direct measurements of the complex admittance allowed us to extract all four values of the equivalent circuit model components of the tuning fork crystal oscillator.