New Dipole Magnet Test:|
A Technical Division Success
The Technical Division celebrated the successful tests this month of two
new magnets. In tomorrow's issue, we discuss the super-ferric, low-field
magnet developed by Henryk Piekarz's team; today we talk about the new,
Capping a two-year effort, Sasha Zlobin and his collaborators have achieved a
significant milestone this month with the successful testing of a new
The magnet is a superconducting dipole based on niobium-tin (Nb3Sn). The Nb3Sn
technology, which could eventually produce fields of more than 15 Tesla, is being
developed for future LHC upgrades and, in the longer run, for a possible Very Large
Hadron Collider (VLHC). Current superconducting accelerator magnets, based on
niobium-titanium, are limited to fields below 9 Tesla.
"The magnet worked as well as it
possibly could--100% of the performance limit. Previous tests had only
reached 60% of the performance limit," said TD head Bob Kephart.
At first, Nb3Sn posed a serious problem: It produced excessive heat. Zlobin's
team figured that the heat might come from instability in the magnetic field.
Vadim Kashikin demonstrated that hypothesis theoretically, and to check it, one
year ago the team adopted "powder-in-tube" filaments. "They have the best
stability, because the filaments can be made very thin," said Zlobin, and thinner
filaments produce stabler fields. This month's test of the redesigned magnet was
In addition to creating very strong fields, Nb3Sn magnets can operate at up to
4.5 Kelvin, compared to the 1.9 Kelvin of current LHC magnets. This
could be a significant advantage especially near the interaction region, where
"most of the heat produced by particle collisions ends up in the magnets," said
former TD head Peter Limon.
Now the team plans to switch to other kinds of thin Nb3Sn filaments that could
eventually produce even stronger fields. "Our goal is to reach 15 Tesla for
quadrupole magnets," Zlobin said.