# Presentation: 493769

## What Will It Take to Have a Viable Proton Source through 2010?

- Elliott McCrory and Eric Prebys
- December 20, 2002

## Outline

- Pre-Accelerator and Linac
*Elliott, et al.*
*Vacuum tubes, power supplies, old equipment, personnel*
- Booster
*Eric, et al.*
*Activation, HL & LL RF, old equipment*

## Overview of Linac Concerns

- Pre-Accelerator
- Low Energy Linac
*Vacuum Tubes*
- Especially the 7835 Power Amplifier triode
- LEL High Voltage Modulator
*F-1123 (switch tube)*
*“**QPS” power supplies*
*Tank 1*
- High Energy Linac
*Radiation & Activation *
- All fixes are Band-Aid patches
*Big $ & personnel outlay that is otherwise useless to the needs of the Laboratory further in the future*

## Pre-Accelerator

- Reliable operation is likely through 2010
*Retirement of Hren and Wendt: 2015?*
- No particular supplier problems
*Although we have had some interesting problems with the various components, e.g., power tubes. *
- Will need to replace the Haefley HV supply with a better regulated model
*Line voltage variations are barely acceptable now.*

## Linac Vacuum Tube Docket

## Very complex technology
RF, material science, vacuum, chemistry
Similar to other tubes made by Burle
4616 & 4617
7835 only used in the scientific community.
One military user for 4617
Quality varies from decade to decade

*RF, material science, vacuum, chemistry*
- Similar to other tubes made by Burle
*4616 & 4617*
- 7835 only used in the scientific community.
*One military user for 4617*
- Quality varies from decade to decade

- The 7835 Power Triode

## Burle Industries, Lancaster, PA

- Enormous facility
- Makes all kinds of tubes
*Power tubes*
*PMTs in competition with Hamamatsu*
*Some picture tubes*
- Was RCA Tube plant
*Radar tubes for AWACS*

## Histogram of Tube Lifetime

**Total Tube Hours**

- Average: 11726*
- Median: 11674*
- Sigma: 5522*
- **Removing outliers (Tank 1)*

- Updated 12/17/2002

## In Service Now

**5 stations**

**9 stations**

*Three tubes with*
*>30000 hours excluded*

- Updated 12/17/2002

## Tube Throughput with Burle

- Median lifetime: 16 months
*Recent lifetime: Less!*
- We need about 3.41 tubes/year to maintain
*Assuming historical median*
*With present tubes: *_*twice that*_*.*
*We have received 5 tubes in the last 12 months*
- Including one borrowed from Argonne
- Expect 7 tubes over the next 12 months; next in February
- Burle now can make/rebuild ~20/year
*Critical path: Final bakeout; two stands, 3-5 weeks bakeout*
*Also of concern: Supplier delivery time (e.g., ceramics, cathode)*
- Delivery time: ~8 months,
*But, often 12 months!*

## Ave: 6.8

- Ave: 2.75

- 9 Sockets

- 5 Sockets

## Why Would Burle Stop Making 7835s?

- If a supplier is not able to deliver raw materials
*~1987: Thorium content of cathode dropped from 2% to 1.5% due to EPA issues at supplier*
*Quality ceramics always hard to get*
- If demand for 4616 tubes dries up
*E.g., our Switch Tubes (in modulator)*
*Military still uses lots of these*
- ~100s of these per year currently
*Burle’s “Bread & Butter” for this type of tube*
- If life of tube is less than the delivery time!
*Tubes must last >>8 months in operation to be practical.*

## Alternatives?

- To the 7835?   None, really.
*This is the highest power 200 MHz tube in the world*
*Los Alamos is looking into 3.5 MW “Diachrode”*
*201 MHz Klystron?  Not likely!*
- Pooling 7835s among the four US DOE Labs?
*BNL: 9 sockets, Argonne: 1, Los Alamos: 5, FNAL: 5*

## Summary: Will We Have Power Tubes in 2010?

- Maybe, maybe not.
- Burle has every intention to make these tubes forever, but ...
- Which “secondary” triode is going to stop being produced next???
- What can we do now?
*Not much*
*Use spare tubes from other labs*

## LEL High Voltage Modulator

- Switch tubes are no longer made
*Military demand for F-1123 ended abruptly*
*Triton closed the one remaining production line in 2002*
- We have 61 spares right now
*2 y average life, 15 in service **** replace 8 per year, 7 years left*
*Econco may be able to rebuild these tubes*
- 2010 is possible, but not much more.
*The clock is ticking!!*
*2020 is unlikely with this system*
- What can we do now?
*New Modulator design*

## Low-energy End Quad PS

- 300 A, 200 V pulsed (15 Hz) power supply
*There are 116 supplies in service*
- Largest inventory of PCBs on site
- Ancient technology
- Circuits rebuilt many times
- What can we do now?
*Decide on replacement technology and replace them, starting now*

## Ancient Technology

- Note Burn Marks

## The Inside of a QPS Chassis

- Small PCB caps
- 10 PCB capacitors at 2 pounds each

## 7835 Filament Power Supplies

- 7000A, 5VDC output  (480VAC input)
*~35KW just to light the filament.*
- Hardware unreliable and hard to maintain
*One original spare exists (LRF6).*
- Upgrade Controller
*Begun by Ma and Wahl*
*One working new prototype at LRF7, but still needs minor interfacing work.*
*PLC used is now obsolete; better units available but means more development work.*
- 2010? Probable, with the controller upgrade
*This needs to be funded*

## O-rings on LEL Quadrupole Stems

- Have lost ~10 (aside from Tank 1)
*16 years since the last failure*
- When will they become too old to hold vacuum?
*Tank 5: More radiation exposure that ever*
- 2010?  January 2003 shutdown will give us information on the state of the o-rings now

## Tank 1

- Remember: This was a prototype!
- If we lose a quad in Tank 1 (e.g., to a short), it may take _months_ to recover
*No post couplers—will be difficult to realign the quad and, simultaneously, stabilize the RF fields; Bead pull?!*
- Continuous pumping on the stem box covers
*Some o-rings may be damaged*
*Cannot regulate field w/changes in atmos. Pres. unless we pump*
- 2010?  With a little luck.
- O-rings and Tank 1: What can we do now?
*Nothing.*

## Other LEL Concerns

- LEL LLRF
*Should be relatively easy, inexpensive and interesting upgrade project*
- Water Systems
*Upgrade underway now, should get us to 2010, but not 2020.*

## Radiation Concerns in the HEL

- Activation of components
*Delivering more beam than ever!*
- And they want a lot more!!
*Areas at 100 mR/hr @ 1’, but component damage seems unlikely*
*Hands-on maintenance may become problematic*
- External shielding
*At ~50% of the trip point for some detectors outside of the tunnel*
*Wire scan trips off the interlocked detectors quickly*
*Significant improvement in reducing losses required, or*
*Big redesign of the passive shielding*

## Number of Beam Pulses/Day

- 1.6 Hz

## Other Concerns in the HEL

- What is the real lifetime of the klystrons?
*Will they all fail at once?*
*Will need to send klystrons to Litton to keep their line active.*
- Are there other components that are going to fail *en mass*?
- Obsolete LLRF computers
*Upgrade in planning stages now*
*Need $$ for this upgrade*
- HEL 2010?
*Will need to reassess external shielding*
*Otherwise, no problems here*

## 2010? Gambles

- Can we get enough 7835s?
*And will they last long enough?*
- Will the supply of Switch Tubes be enough?
- Will Tank 1 break?
- Will the drift tube stem o-rings survive?
- Will radiation/activation become a problem?

## 2010? Specific Fixes

- Haefley HV Supply
- Inter-lab spares for 7835 power tube
- Redesign the LEL Quad PSs
- Replace filament supply controllers
- Continue design effort for LEL modulator
- Replace the LLRF in the LEL
- Upgrade the computers in the HEL LLRF
- More shielding may be necessary at high-energy end
- Big $ & personnel outlay that is otherwise useless to the needs of the Laboratory further in the future

## Beyond 2010?

- Young’s proposal for new LEL
*Two ion sources and injector RFQs to ~1 MeV*
*“**Double alpha” injection into *
*RFQ to ~7 MeV*
*400 MeV commercial drift tube Linac*
*New, gentler transition section at ~70 MeV*
*New 805 MHz SCCL module(s) to 116 MeV*
- Price tag: ~$N x 107.

## 402 MHz Parameters from Young

- Price tag: About $40 x 106.