RF Cavity of CIS Xiaoying Pang Mar. 12 th, 2007 IUCF.
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Transcript of RF Cavity of CIS Xiaoying Pang Mar. 12 th, 2007 IUCF.
Present Design of CIS
• Energy=25MeV• The Lowest frequency f=16.6MHz• HARM=1(for the MPI cavity)• We can choose the right voltage to get longer life times. • The power should also be affordable.
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Kinks are located in the region [0.04:0.06] [GeV]. From the above graph we can tell, is smooth in this region. There must be somethingelse responsible for this. We will investigate this in the future.
MPI Cavity• Wide tuning range with external quadrupole ferrite biasing (1.3MHz
to 10MHz correspond to proton energy 7MeV-200MeV)
In the ferrite materials, as the
bias current increase, the biasing
magnetic field increase, but the
effective permeability decrease.
So we can achieve resonance at different frequency and also reduce the length of the cavity.
(This kind of scheme proposed by S. Papureanu and first adopted
at Max Planck Institute. So called MPI cavity)
Diameter of the cavity ~0.55m; Length ~0.6m
10 Philips accelerator ferrite rings:material: 8C12; dimension
• RF power is coupled into the cavity by a driving port which is directly tapped to the
center conductor of the cavity. The port is a magnetic loop.
• 40 turns of windings are put on each tip of the quadrupole
The center of the ferrite ring where the beam pipe is located is well protected from the biasing field due to the canceling of the field at the center
• The outer conductor is make of copper stripes. The inner conductor is perforated. A fan forces air through all these air passages to keep the ferrite and cavity cool.
• A 70mm gap between the loop magnet and main magnet. The loop biasing magnet is used for the input impedance matching
Our goal is to increase the resonace frequency but make the shunt impedance as high as possible. So we may need to make the loaded capacitance lower (around 100pf) or cut the length of the cavity.(Q=40)
We are trying to model this cavity. We will ultimately get more understanding from the real experiment!