Re:large duty cycle and probe damage...in BRUKER systems

From: Khan <nmskhan_at_hotmail.com>
Date: Sat, 2 Jul 2005 14:04:49 -0500

Hi

I would probably include few lines of statement in the pulse program, allowing
it to abort the system running if it exceeds the duty cyle or decoupling power or even pulse length.

Usually, there is a "C " statement in the Varian MRI pulse program,
for example

if (tDELTA > tDELTAmax) {
  abort_message("%s: tDELTA too large for te. Max tDELTA= %f ms. Minte= % f ms",
                      seqfil,tDELTAmax*1e3,temin*1e3);

I hope, This will help.

Thanks
Khan Hekmatyar
  
*********************************************
Shahryar K Hekmatyar, Ph.D.,
Department Of Radiology,
Indiana University School of Medicine
Indianapolis -46202, IN
Phone: 317-278 8649.
Fax: 317- 274-8124.

shekmayt_at_iupui.edu


Dear Friends

    I am posing the following questions specifically with Bruker Avance
(DMX, DPX, DRX, AV, etc..) systems in mind.
    Can you outline the strategies you follow in your respective labs,
to avoid users driving too much power into the probes and damaging them ?
 Specifically, I would like to ask :

* How do you limit the CW power being too high (say in a decoupling situation ) ?
* How do you make sure that the users do not accidentally use "seconds"
for pulse durations instead of "microseconds". ( To my knowledge, in
XWINNMR software, pulses p0-p31 have a default unit of 'microseconds'.)

    Recently I had the X-coil of a BBO probe gutted down by excessive
pulse length or power or a combination thereof, on a AV300 system. It
was an expensive repair to replace the coil and some capacitors inside
the probe. I want to minize the possibility of such a nightmare recurring.
    I tried as much as I could to do a forensic analysis of the datasets
that were collected prior to the accident but could not find any tracks.


    Any input would be greatly appreciated.

Thank you very much, as always.

Rajan

--
*_______________________________
Rajan K Paranji, Ph.D.
*NMR Facility Manager
Department of Chemistry
Room 65, Bagley Hall
Univeristy of Washington
*Seattle, WA 98195
ph: 206 685 2581
fax: 206 685 8665
email: paranji_at_chem.washington.edu
Received on Wed Jul 06 2005 - 12:37:58 MST

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