Abstracts Brochure - CERN

TUPLS107
TUPLS108
TUPLS109
27-Jun-06 16:00 - 18:00 TUPLS — Poster Session
Operation of the Opposite Field Septum Magnet for the J-PARC Main Ring Injection
The opposite field septum magnet system
I. Sakai (KEK)
has been applied to the injection system of
the J-PARC 50-GeV proton synchrotron. The
features of the system are a force-free structure, easy pulse excitation and the possibility of a large-aperture, thinseptum
structure. The septum magnet has the structure of an inside-vacuum to eliminate the thickness of the vacuumchamber
walls and electric-insulation layer to make the septum thickness as thin as possible. However the magnet
cores and return coils are outside of the vacuum to reduce the out-gassing rate of the vacuum system. Finally, the
larger beam aperture than the full acceptance of the ring and larger separation angle can be obtained at the septum
magnet for low-loss injection. In this paper we will introduce the methods to eliminate the error fields caused by
fabrication errors and eddy current with pulse excitation and stability of high current power supply of 50 kA.
Realization of Thick Hybrid Type Carbon Stripper Foils with High Durability at 1800K for
RCS of J-PARC
I. Sugai, Z. Igarashi, K.I. Ikegami, C. Kubota, A. Takagi, Y. Takeda
(KEK) T. Hattori, K.K. Kawasaki (RLNR) Y. Irie (JAEA/J-PARC)
H.K. Kawakami, M. Oyaizu (New Affiliation Request Pending)
252
The J-PARC requires thick carbon stripper
foils (250-500 ug/cm 2 ) to strip electrons from
the H-beam supplied by the linac before injection
into a 3 GeV Rapid Cycling Synchrotron.
The 200 MeV H − beam from the linac
has a pulse length of 0.5 ms with a repetition rate of 25 Hz and an average beam current of 335 uA. By much energy
deposition of these high-intensity H − and circulating bunched beams, commercially available best stripper foils (CM)
will break in a very short time and even a diamond foil will rupture at around 1800K by MW class accelerators. We
have realized for first time the hybrid boron doped carbon stripper foils with long life time for J-PARC. The foils of
250-500 ug/cm 2 were made by a controlled DC arc-discharge method. The lifetime was tested by using 3.2 MeV Ne +
DC beam of 2.5 uA and 750 keV H − DC beam of 500 uA, in which a significant amount of energy was deposited in
the foils. The maximum lifetime was extremely long, 120- and 480-times than those of diamond and CM foils. The
foils were also free from any shrinkage, and showed low thickness reduction rate even at high temperature of 1800K
during long time irradiation of 90h.
Present Status of the L3BT for J-PARC
L3BT is a beam transport line from J-PARC
T. Ohkawa (JAEA) H. Ao (JAEA/LINAC) M. Ikegami (KEK) (Japan Proton Accelerator Research Complex)
linac to the succeeding 3-GeV RCS
(Rapid Cycling Synchrotron). The construction of the L3BT has been almost finished. The beam commissioning
of the L3BT will be started soon. On the other hand we have performed 3D particle simulations with PARMILA and
IMPACT to evaluate the performance of the halo scraping, momentum compaction and beam diagnostics. In this
paper, results of the beam simulation of the L3BT are presented. The construction status of the L3BT is also presented
in brief.