Development of EM wave guide amplifier potentially used for sea bed logging (SBL)

Seabed logging is a new technology being
implemented for deep target exploration. The technology uses
electromagnetic (EM) wave where an antenna transmits EM wave into
water layer underneath seabed and with resistivity characteristics of
hydrocarbon reservoir, the wave is reflected and received by the detectors
on the seafloor. However, the roughness of the sea caused by underwater
sea current limits the transmission of EM wave. EM wave itself has its own
attenuation in seawater that is 102dBm and the underwater sea current
has made it worst. In seabed logging technology, the vessel is towing the
transmitter at a very slow speed (1.5km/h) with high EM wave energy for
transmitting the waves of ~1250A/cm2. Due to this large current more heat
is generated. In this project, we propose an EM waveguide amplifier to be
used to overcome these problems. The EM waveguide amplifier amplifies
the wave without modifying the transmitter (antenna) circuit. Therefore
lower energy is required for the transmitter and is sufficient for seabed
logging technology. The thermionic cathode and molybdenum (Mo) anode
with work function of 1eV are selected to get higher amplification of EM
wave. It is found that potential difference between the cathode and anode
improves the electron acceleration in the waveguide amplifier. It has been
observed that with the use of wave guide amplifier and with 20 Vpp supply
to the transmitter at 5MHz frequency, the wave received by receiver has
been amplified up to 170%. The application of this new method in seabed
logging shall reduce the heat generated and overcome the EM wave
attenuation problems.