Cooling Channel Linac RF Power Source

Preliminary Requirements

December 1999




Cooling Channel Linac RF Power Source Preliminary Requirements:


Frequency 201 MHz
RF Power 5 MW per Meter
RF Pulse Width 150 usec
Rep Rate 15 Hz
Length of Channel ~150 Meters

Given the above parameters to work with, we propose the following high power rf devices. We have decided at this early stage to go with a Klystron (even though the length is an issue ~ 7.75 Meters) because it is less risky than other devices at this time and should last a very long time. MTBF is important since there will be about 75 systems operating in the Cooling Channel Linac along.

The present first half of the FNAL Linac uses a 5Mwatt Triode (Burle 7835) operating at 201 Mhz. To consider this for the proposed application would indicate the need for one of these amplifiers every meter of cooling channel length (150 stations). Taking into account all the supporting equipment needed to operate a single 5 Mwatt station (modulator, 250Kwatt driver, solid state predriver, associated power supplies, etc), this option does not look cost effective or even manageable.

This indicates that we need to consider an rf power source with at least 10 Mwatts of peak rf power.

We propose to have one Klystron feed two (2) meters of cavity structure. For a one hundred fifty (150) meter long Cooling Channel, seventy-five (75) high power rf systems will be required.

Other possible ultra high power sources for 200 Mhz operation, such as IOT (Inductive Output Ttubes), special tetrodes, and other unique devices might be a viable (and cost effective) solution in the years to come with proper R&D funding.

Proposed RF Station Blocks:


  1. RF Power Source, Multibeam Klystron
    Peak RF Power output 10 Megawatt
    Beam Voltage ~65 KVolts
    Beam Current ~310 Amps
    Rep Rate 15 Hz
    Efficiency ~50%
    Gain ~50 dB
    Physical Length of Klystron ~7.75 Meters
    Klystron Weight ~12,000 lbs.
    Soleniod Power ~ KWatts
    Soleniod Weight ~ lbs.

  2. Modulator for Multibeam Klystron
    Solid State IGBT
    Voltage 65 KVolts
    Peak Power 20 MWatts
    Current 310 Amps
    Average Power 60 KWatts
    Pulse Width 200 usec
    Size 1.2 X 1.2 X 2.4 Meters
    Rep Rate 15 Hz
    Droop ~5%

  3. 12 inch Diameter Coaxial Copper Transmission

    12 inch diameter rigid copper coaxial transmission line with brass flanges.


  4. Water Skid for Accelerating Cavity

    Water system that will supply tempered water for each two (2) meters of cavity. This local water skid will have its own heaters, pumps, DI loop, and heat exchangers with primary cooling to the heat exchanger supplied from a central chilled water loop.


  5. Station Relay Racks

    Each rf station will have five (5) racks for housing controls, power supplies, LLRF, and a 250 watt solid state driver amplifier.


  6. Utilities

    Electrical Power -
    Cooling Water -
    Cable Trays

  7. Installation


  8. Equipment Gallery Layout
    Cooling Channel LINAC Equipment Gallery Layout
    Cooling Channel LINAC Equipment Gallery Cross Section


Last Updated: 31 January 2000