Design of a high-power NMR probe for low-temperature studies.
A low-temperature, high-power NMR probe head design is described which eliminates the problem of electric arc discharge commonly experienced during radiofrequency pulse cycling in a helium environment. A polychlorotrifluoroethylene (Kel-F) coil former, fitted with a solenoid coil, is heat-shrunk onto stainless-steel flanges and spot-welded inside a stainless-steel probe head assembly connected to a hollow coaxial transmission-line probe shaft. By this means, the sample coil and all high-voltage elements can effectively be isolated in a vacuum, while at the same time permitting good thermal contact between the sample and cryogenic gas. This design was used in NMR studies in the 4.6 K < or = T < or = 77 K temperature range for RF pulse durations < or = 50 ms (and longer for low RF amplitudes) and amplitudes up to approximately 60 G.
Damyanovich
A Z
AZ
Department of Medical Imaging, University of Toronto, Ontario, Canada.
Peternelj
J
J
Pintar
M M
MM
D003080:Cold Temperature; D004867:Equipment Design; D006371:Helium; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D011095:Polyethylenes; D013193:Stainless Steel
D011095:Polyethylenes; D013193:Stainless Steel; D006371:Helium; C039184:polychlorotrifluoroethylene