Figure 2
From: A miniaturized spectrometer for NMR relaxometry under extreme conditions
The HTHP NMR probe. (A) The machined PEEK capillary, both side view and front view (inset); (B) The installed PEEK capillary on the probe head; (C) A schematic cross section of the HTHP probe. To equalize pressures across the capillary wall, the space in between of the capillary outer wall and the pressure vessel is filled with fluids of equal pressure. The annular space is further partitioned into two chambers (left and right) by a PEEK piston. To avoid interference with signals from the sampled fluids, the pressure-compensation fluids in the left chamber are fluorinated hydrocarbons. In contrast, the fluids in the right chamber come from the capillary, which enter the space through the compensation port. When the operating condition varies, the piston moves so as to maintain pressure equilibrium across the capillary wall.
