In this work we present experimental investigation of the MgB2 hot-electron bolometer (HEB) for low noise mixing at
terahertz frequencies. A dedicated MgB2 thin film deposition system was designed and constructed based on Hybrid
Physical-Chemical Deposition. Films as thin as 15nm have a superconducting transition at 35K, with a critical current
density <107 A/cm2 (at 4.2K) in bridges as narrow as 500nm, indicating on good connectivity in the film. The gain
bandwidth (GBW) was measured by mixing of two THz sources. The GBW is proportional to the film thickness and it is
at least 6GHz for 15nm thick devices. Performance of MgB2 HEBs was compared to performance of one of the NbN
HEB mixers made for the Herschel Space Observatory (one of the flight units), for which both the GBW and the Noise
Bandwidth (NBW) was measured. MgB2 HEB mixers show a GBW at least a factor of three broader compared to the
NbN HEB measured in the same set-up.
In this paper we consider using the terahertz (THz) time domain spectroscopy (TDS) for non destructive testing and determining the chemical composition of the vanes and rotor-blade spars. A versatile terahertz spectrometer for reflection and transmission has been used for experiments. We consider the features of measured terahertz signal in temporal and spectral domains during propagation through and reflecting from various defects in investigated objects, such as voids and foliation. We discuss requirements are applicable to the setup and are necessary to produce an image of these defects, such as signal-to-noise ratio and a method for registration THz radiation. Obtained results indicated the prospects of the THz TDS method for the inspection of defects and determination of the particularities of chemical composition of aircraft parts.