Transverse space-charge effects in heavy-ion storage rings for intertial-confinement fusion
Nuovo Cimento Della Societa Italiana Di Fisica A-nuclei Particles and Fields(2008)
摘要
Summary The space-charge-induced crossing of half-integer and integer stop bands is examined for storage rings proposed to drive inertial-confinement
fusion. Two different approaches are used: a classical resonance crossing picture and a diffusion model based on the addition
of kicks due to field errorw with phase randomization due to rapidly changing tune shifts. Gradient and bending field tolerances
to permit crossing of stop bands with acceptable emittance growth are established and compared to those observed in existing
machines like the CERN-PS. Two different situations are to be distinguished in driver rings: the «stacking plus holding» period
(of 5–50 ms) during which the rings are filled and the final bunching (during 10–50 μs) when the bunches are compressed from
typically 100 to 10 ns length prior to extraction into the final transport system. Gradient tolerances to permit stop band
crossing are found to be Δ(kl)/kl≤10−4 per quadrupole during stacking and ≤5·10−3 during final bunching; compared to a few 10−3 observed in the PS. Tolerances to survive resonances driven by bending field errors are Δ(Bl)/Bρ≤5·10−6 per element even in the final bunching period; an order of magnitude smaller than «typical» uncompensated values in the PS.
Stop bands driven by gradient and bending field errors are affected by the «incoherent» and the «coherent» tuneshifts respectively.
Hence for the driver rings one may contemplate working with a large incoherent tuneshift (ΔQ
ic≤5) during final bunching but keeping the coherent detuning (during stacking and bunching) and the incoherent detuning during
stacking small enough (ΔQ≤0.5) to avoid resonances in these conditions. The more conservative approach to avoid gradient error resonances even during
final bunching leads to difficult constraints for other parameters. Experiments on the PS to test fast resonance crossing
are also briefly discussed.
更多查看译文
关键词
inertial confinement fusion,space charge,diffusion model
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要