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[atf2-magnet 8] Re: ff3.4 magnet list: 2 questions

Dear  Cherrill,

       Regarding (1), Yes, we have the beam energy limitation of 1.3GeV which main magnet of damping ring limits due to temperature rise and insufficient cooling system. So, you can design magnets with 1.3GeV.

      Regarding (2), Yes, it is the rotating coil. You can ask the detail of this to Kuroda who used it to measure the field of ATF Quads.

Best wishes,

At 10:05 PM -0700 05.4.14, Spencer, Cherrill M. wrote:
> Dear Tauchi-san and Urakawa-san
> Continuing the discussion about beam energy and quad apertures for ATF2:
> (1) Has Urakawa-san come to any conclusions about the beam energy we should be designing the magnets for?
> (2) I would like to know some more details about your magnet measuring device.
> For example, is it a rotating coil? does it have multiple windings in a fully bucked arrangement?
> We will want to make precise measurements of the quads' multipoles and for this we need a fully -bucked rotating coil. Our Magnetic Measurement expert here at SLAC, Zachary Wolf, explained to me that it is difficult to make a fully-bucked coil of under ~1inch ~ 25mm diameter and so we wouldn't want to make the quad apertures smaller than about 28mm. This value is not so far from 32mm to make much difference in the quad fabrication cost,  so we can stay with the 32mm - as long as your measuring device makes precise measurements of the higher order multipoles.
> If it doesn't then we should consider making a new rotating coil or maybe having the magnets measured somewhere else-- depends somewhat on where they will be built I suppose?.
> I have looked up old KEK papers on  magnets being measured but can only find papers on the KEK-B magnets, who could I correspond with at KEK to discuss further these measurement questions?
> Regards from
> Cherrill Spencer
> 650-926-3474
> ________________________________
> From: ?? ?? [mailto:toshiaki.tauchi@xxxxxx]
> Sent: Fri 4/8/2005 4:51 PM
> To: atf2-magnet@xxxxxxxxxxxxxx
> Subject: [atf2-magnet 6] Re: ff3.4 magnet list: 2 questions
> Dear Cherrill,
> > (1) I understand the ATF never runs above 1.28GeV and is unlikely to, so can
> > we design the magnets for the 1.28GeV beam and not for a 1.54GeV beam? It will
> > make the magnets approximately 20% weaker and hence smaller and  cheaper.
> All the magnets have been designed for the 1.54GeV beam at the ATF damping
> ring(DR) and extraction line(EXT).  So, we would like to follow the
> tradition.  However, for cost reduction, we had better address this beam
> energy issue as you pointed out.  I would like to ask the ATF expert's
> opinions first.  So, Urakawa-san, please comment on this issue.
> > (2)  Why do the quads have a 32mm diameter aperture when the ID of the
> > beampipe is just 16mm? With a typical beampipe thickness I suppose the outer
> > diameter of the beampipe would be about 20mm and I'd prefer to make the quad
> > aperture match this.
> > Is the 32mm dictated by the BPM size? Again, a smaller aperture would lead to
> > cheaper magnets.
> Also the 32mm diameter aperture is common at the existing ATF beam line (DR
> and EXT).  Our device of magnetic measurement was designed for the 32mm
> aperture.  So, it can not be used for smaller aperture.
> Best regards,
> Toshiaki T.

Junji Urakawa , KEK
Tel 81-29-864-5311
Fax 81-29-864-0321