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Low
Decoupler Heating Using Low E-Field Coils.
A
Long Tradition at Doty Scientific... since 1997.
Lowest
decoupler heating
using Doty's two coil approach.
The inner
cross coil introduced in 1997 had 110 kHz decoupling fields at
750 MHz with 6 to 25 times lower sample
heating compared to solenoid-only probes.
Stable
tuning, low heating, high sensitivity, and excellent B1 matching
on both coils, even for lossy samples. Unlike many other sample
coil designs,
the B1 homogeneity of the Doty cross-coils is not
significantly affected by the sample because of its inherent
electrical balance
(low E-fields), symmetry,
and
very low inductance.
What is
a cross coil?
The cross coil is a “saddle-type” coil that has an
inner one-turn loop in parallel with a segmented turn on each side.
Why use two coils?
Using two orthogonal coils simplifies tuning and permits higher
RF fields in larger samples and at very high B0.
How does this help ?
The low inductance cross coil contributes much less to sample
heating during decoupling.
Decouple
Heating
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Doty
two coil approach...
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The DE (Doty Entzminger) coil with
an inner solenoid on a BMAXXY probe.
The inner solenoid provides the Highest
sensitivity on X and Y. The low E fields DE coil provides low decoupler heating.
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The inner cross coil of the PROTONMAX Probe.
 1997
Highest
decoupling efficiency, with inner the PROTON
coil
Longest acquisition times with full decoupling,
150-300 ms
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Using
two orthogonal coils simplifies tuning and permits higher
rf fields in larger samples at very high B0.
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In 1997 Doty
Scientific introduced a new MAS probe that used a low
inductance 1H cross coil with low electric
fields, and very low decoupler heating. It was called
the "XC" (for
cross coil) and was unveiled at at the 38th ENC in Orlando
Florida, March 23-27 ,1997. With all the disscussion
about low-E coils in the last few
years,
some of you may be surprised to learn
that the Doty PROTONMAX cross-coil probes
have been delivered with reliable low-E field
coils
since
1997,
and now our BMAXXY
probes, are being delivered with reliable low-E
field
coils.
And the Doty CryoMAS probe will feature low inductance,
low-E 1H coils.
Below you
can link to a brief record of Doty's low-E Cross Coils.
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Download: One
of the Doty cros-coil probe patents - Patent # US 6320,384B: "Thermal
Buffering of Cross Coils in
High power NMR Decoupling"
Provisional
application (priority date) December 23, 1996,
Filing date December 19, 1997.
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Download: a
pdf of the technical poster presented at ENC, 2004 and
ISMAR, 2004
"Reducing
Decoupler Heating by an order of magnitude
in Triple-Resonance
MAS NMR Probes at 750 MHz "
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