Other types of FFAG
The non-scaling FFAG is a promising idea, but it is not clear whether the resonance crossing during
acceleration is harmless. There are more concerns when we design an accelerator with moderate
acceleration rate with moderate RF voltage such as one for particle therapy. In fact, a simulation study
showed that, at the very least, more accurate alignment is required when we accelerate a beam at a
slower rate in a linear non-scaling FFAG [15].
It is possible to fix a tune without following the cardinal conditions. One way is to start with the
design of a scaling FFAG and relax the conditions. For example, we can truncate Eq. (9) at some
particular order. Lattice magnets can be rectangular in shape instead of radial sector type. In these
magnets, equipotential lines are straight rather than arcs of a circle. Within a unit cell, three magnets
forming triplet focusing are aligned along a line instead of a circle. With careful design of the field
profile in each magnet, it is still possible to ensure the tune variation is negligible over a wide range of
momentum [16]. This design principle does not follow the scaling rule, but it does not use linear
quadrupole magnets either. Therefore, it is called a non-linear non-scaling FFAG.
We can fix the tune, based on a linear non-scaling FFAG design, by introducing non-linear
magnetic fields. It is like introducing sextupole magnets to correct chromaticity in a synchrotron
lattice. Sextupole components are not enough, however, to correct the tune over a wide momentum
range. Higher-order non-linearities such as octupole and/or decapole are required. This is another
approach to designing a non-linear non-scaling FFAG
Other types of FFAGThe non-scaling FFAG is a promising idea, but it is not clear whether the resonance crossing duringacceleration is harmless. There are more concerns when we design an accelerator with moderateacceleration rate with moderate RF voltage such as one for particle therapy. In fact, a simulation studyshowed that, at the very least, more accurate alignment is required when we accelerate a beam at aslower rate in a linear non-scaling FFAG [15].It is possible to fix a tune without following the cardinal conditions. One way is to start with thedesign of a scaling FFAG and relax the conditions. For example, we can truncate Eq. (9) at someparticular order. Lattice magnets can be rectangular in shape instead of radial sector type. In thesemagnets, equipotential lines are straight rather than arcs of a circle. Within a unit cell, three magnetsforming triplet focusing are aligned along a line instead of a circle. With careful design of the fieldprofile in each magnet, it is still possible to ensure the tune variation is negligible over a wide range ofmomentum [16]. This design principle does not follow the scaling rule, but it does not use linearquadrupole magnets either. Therefore, it is called a non-linear non-scaling FFAG.We can fix the tune, based on a linear non-scaling FFAG design, by introducing non-linearmagnetic fields. It is like introducing sextupole magnets to correct chromaticity in a synchrotronโครงตาข่ายประกอบด้วย Sextupole ส่วนประกอบจะไม่เพียงพอ ไร แก้ไขเพลงผ่านโมเมนตัมที่มากมายช่วงนั้น ขั้นสูงไม่ใช่-linearities เช่น octupole หรือ decapole จำเป็น นี้เป็นอีกวิธีการออกแบบ FFAG ไม่ได้มาตราส่วนไม่ใช่เชิงเส้น
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