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:
| 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. |
| 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% |
12 inch diameter rigid copper coaxial transmission line with brass flanges.
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.
Each rf station will have five (5) racks for housing controls, power supplies, LLRF, and a 250 watt solid state driver amplifier.