A New MIRF System

1
A New MIRF System

• David Wildman
• Alex Chen, Zubao Qian, Vincent Wu
• March 16 , 2005

2
Outline

• Specifications
• Beam Loading and Stability
• Cavity Design
• Mafia Simulations
• Costs
• Conclusions

3
Specifications

• Intensity of 1.5E14 per MI cycle
• Maximum ramp rate of 305 GeV/s
• Cavity peak voltage of 300 kV
• 18 RF stations - same as current system
• Frequency sweep 52.814 MHz to 53.104 MHz

4
Beam Loading

• Both transient and steady-state beam loading are
  proportional to the cavity shunt impedance, Rs,
  divided by the cavity Q.
• Rs/Q only depends on the cavity geometry
• For a coaxial quarter wave resonator, Rs/Q can be
  adjusted by changing the characteristic impedance
  of the line
• The new RF cavity will have 4x smaller Rs/Q
• Rs/Q reduced from 104 to 25.
• This will enable us to achieve 4x the present
  intensity with the same beam loading effects we
  see today.

5
Beam Stability

• For a detuned cavity without feedback, the RF
  system reaches the Robinson instability limit
  when the power dissipated in the cavity equals
  the power being delivered to the beam.
• For our case, the maximum power delivered to the
  beam will be 407 kW/cavity.
• The maximum power dissipation in the cavity is
  chosen to be 450 kW.
• Guaranteeing beam stability without any feedback
  is the most conservative design.

6
System Specifications

• Rs/Q 25, low Z transmission line
• Rs/Q 100 k?, Q 4000 from copper coated
  stainless construction.
• Perpendicularly biased garnet tuners
• Present RF system will be driver for new system.
• Power tetrode CPI Eimac 8973 (1MW) or Thales
  TH525 (1.5 MW)

7
New RF Cavity
8
New RF Cavity
9
Simulation Model for Main Injector New Cavity
with TunerVincent Wu (MI Dept)
Blue copper Teal stainless steel Green ceramic
window Red ferrites
10
Tuning Range vs. Tuner CouplingVincent Wu (MI
Dept)
Ferrite ?13.5 ?1.2?2.5
11
Cost per RF Station

• Cavity - 150k
• Amplifier - 300k
• 2 MW dc supply - 500k
• Controls - 50k
• Installation - 100k
• Cost per station - 1.1M
• Total cost for entire RF system - 20M

12
CONCLUSIONS

• Conservative design for beam stability
• Total cost 20M excluding civil, utilities, and
  contingency
• The next step -- build a prototype cavity and
  amplifier