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<div class="moz-cite-prefix">Hello Dan and all,<br>
<br>
Let's put this at the top of the list for the next biweekly
meeting's agenda, on 6/24. Sascha, do we need answers before
then?<br>
<br>
-Richard J.<br>
<br>
On 6/11/2013 4:09 PM, Daniel Sober wrote:<br>
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<blockquote cite="mid:51B783F5.3040505@cua.edu" type="cite">
I have finally gotten around to analyzing Yang's Tosca midplane
maps at excitations of 6, 9, 12, 14, 15, 16 and 17 kilogauss. The
results are posted at <a href="http://faculty.cua.edu/sober/HallD/Excitation">http://faculty.cua.edu/sober/HallD/Excitation</a>
.<br>
<br>
The most informative single plot is probably the one labeled "Plot
vs B" (<a href="http://faculty.cua.edu/sober/HallD/Excitation/Bnorm_vs_B.pdf">http://faculty.cua.edu/sober/HallD/Excitation/Bnorm_vs_B.pdf</a>).
If the permeability were infinite, the field per ampere-turn would
be constant at about 0.83 gauss/amp-turn. The figure shows that
the saturation effects are already significant at the operating
field of 15 kG. If you look at the "fine" plots of B/NI versus z,
you will note that the saturation effects are not uniform through
the magnet. For B>15 kG, the field at the ends of the magnet
(z = ±300 cm) is slightly higher than the field at the center
(z=0), while at lower fields the z-dependence is negligible.<br>
Conclusions for mapping:<br>
1. If there is any possibility of running above 12 GeV, we must
map at the highest conceivable field. (What is the expected power
supply limit?)<br>
2. To allow for running at beam energies other than 15 kG, we
should map the magnet at 16, 15, 14, 12 and 6 kG. Some of these
maps may be made at coarser granularity if time is short.<br>
3. Note that the Tosca calculations were made using the "default
steel" permeability table, so we must make measurements at several
excitations to test the reliability of the Tosca calculations.<br>
<br>
I will be traveling in Europe from June 13-July 14. See you next
month.<br>
Dan<br>
<div class="moz-signature">-- <br>
<font color="#ff0000"><i>Daniel Sober<br>
Professor<br>
Physics Department<br>
The Catholic University of America<br>
Washington, DC 20064<br>
Phone: (202) 319-5856, -5315<br>
E-mail: <a href="mailto:sober@cua.edu">sober@cua.edu</a></i></font><br>
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