Ron Akre, Patrick Krejcik
STATUS OF RELIABILITY UPGRADES
Klystron/Microwave Department Nov. 5, 1997
Electronic/Microwave Engineering Group (08D)
To: Marc Ross MS 66
From: R. Akre
Subject: Damping Ring RF Reliability
Below is my categorization of cater data supplied to me from Wayne for the damping ring caused down time between June 1, 1997 and Oct. 29, 1997.
Total items 23
Total days 151
Total hours 3624 SLD = 1384 hrs
Total Beam Time Lost 62.2 hours
Klystron & Magnet 25 hrs
Cavity 590 14.8 hrs
S Band feedback 9.8 hrs
Rate change problems 1.9 hrs still not resolved
VCO 1.5 hrs
Pi Cavity Tune 1.4 hrs
Various Other 6.2 hrs
Wrong Shop 1.6 hrs
Lost Beam Time Hours
|SLD OP YR / hrs||Total RF||KLY||Cavity||Low Level||Stability||Other||% Available|
Current Inventory October
4, 1999 http://www.slac.stanford.edu/grp/kly/amrf/drrf/drhist.html
|C7-08||VA-955H||Varian VA-1955H S/N 0101R.||NDR Socket||Online||No||No||Installed in NDR socket 10-22-97.|
|H4-159||VKP-7555S||Varian VA-1955H S/N 0157||NDR vault||Dressed Spare||No||No.||Water leak repaired, magnet rebuilt|
|J7-11||VA-955H||Varian VA-1955H S/N E7-011R||SDR Socket||Online||No||No||Installed in SDR socket 11-29-98|
|J6-101||VKP-7855||Premier VA-1955H S/N 0123||SDR Vault||Dressed spare||Yes||No|
|C8-507||VKP-7855||None||Sector 1 cage, in crate||New tube||Yes||Until April 2000||Delivered to Sector 1 cage 4-1-98|
Damping Ring Klystron and Klystron Magnet Failures
Jan 21, 1995 Tube C6-14 Water Leak SDR
Jan 23, 1995 Tube H7-11 Gun arc NDR
Mar 22, 1995 Magnet E7-011R Short SDR
Dec 11, 1995 Tube C6-14 Downtime Damage SDR
Jan 08, 1996 Tube C1-19 No emission, Collector Leak SDR
Jan 13, 1997 Magnet 0123 Interlock failed NDR
May 29, 1997 Tube C6-14 Collector Leak NDR
Jun 13, 1997 Magnet 0157 Water Leak NDR
Jun 19, 1997 Magnet 101R Unknown Problem(Installation) NDR
Sep 03, 1997 Magnet E7-011R Water Leak SDR
Sep 09 1997 Magnet 0123 Water Leak SDR
Oct 22, 1997 Magnet 0157 Water Leak NDR
Feb 11, 1998 Tube H4-159 Body OC Faults SDR
Feb 19, 1998 Magnet 0123 Water Leak SDR
Jun 01, 1998 Magnet 0157 Short-Near Old Repair SDR
Nov 29, 1998 Tube H4-159 Water Leak SDR
Magnet E7-011R Mar 22, 1995 repair unknown.
Magnet 0123 was rebuilt by Premier Jun 19, 1997
Magnet 0157 Received New from Premier Microwave Nov 07, 1995
rebuilt by Stangenes Jun 04, 1999
Magnet overheating due to interlock failure partly motivated the interlock upgrade.
The interlock system is being upgraded to better protect the magnets. The SDR interlock system has been upgraded and the NDR interlock system will be upgraded in the near future. Failures due to shorting are expected to decrease.
Magnet water leaks are suspected to be vendor design related. The new vendor has redesigned the cooling system to eliminate the problem areas.
The tube failures occurred with beam voltages of about 24kV. The collector life is reduced at this power level. We have implemented the following three items to improve reliability and klystron lifetime.
Tube H4-159 needs to be run to prove reliability. The tube has been removed in the past due to body current trips. These may have been due to undetected water leak.
Magnets E7-011R and 0123 have an unreliable water cooling circuit.
The water cooling system for the klystron magnet, body, and collector has been a source of down time. The system is worn out and needs replacement.
The water system is integral to the cabinet, which could
also use redesign for maintainability.
Replacement of Klystron with New Type of Tube
Typical IOT Operating Points from Thomson TH770 Data sheet.
Cathode V 34kV
Cathode I 0.7A RF off = 23.8kW Beam
Cathode I 2.8A 63kW out = 96kW Beam = 65% Efficient
Full Power(63kW) Gain = 23.5dB Drive = 300W
Typical IOT Operating Points from CPI K2D110W Data sheet.
Cathode V = 36kV I = 2.2 A (80kW) Collector 47kW
28kW RF out avg. 110kW RF out peak
Gain 20dB minimum RF Drive = 1.2kW
NDR Klystron 135kW Beam Power 25kW Average RF power
SDR Klystron 120kW Beam Power 19kW Average RF Power
Assume IOT output of 25kW @ 40% efficient = 60kW Supply.
Power Savings of 75kW NDR + 60kW SDR =135kW
1 year operation 46 of 52 weeks = 7k Hrs/yr.
= 1GWhr / yr. @ $0.22 / kWh = $220k / yr.
Single Tube Transmitter (High voltage, 34kV, power supply, 1.2kW drive amplifier, interlock system, IOT, all other tube support). All we do is hook up 480VAC power and LCW and we have a high power amplifier.
$400k to $450k each
Leave as is. $10k
New Water cooling system and cabinet $82k
New system can be moved upstairs in the future.
New cabinet will reduce klystron replacement time by 1 hour and reduce likelihood of errors.
Move existing klystrons upstairs $200k
Will reduce down time associated with klystron related problems. Will save about 4 hours in diagnosing and replacing a klystron.
Will reduce calibration time for direct feedback loop and allow access to components during running.
With the system upstairs one less spare klystron and magnet would be required. Magnet $22k, Klystron $80k.
Future availability insured. Replaceable beam stick lowers replacement cost compared to klystron from $80k to $35k.
Will need to review component protection from 130kW-peak power capability, or reduce the peak power capability.
The reliability of the existing system has been greatly increased due to upgrades and lower power requirements. There is nothing currently in the future that will require higher power levels, 2 bunches at 5e10 e-/bunch.
Projections from Debbie Sharrah of CPI are that klystrons will be available for the next 5 years as a standard product and for the next 10 years as a special order.
Redesign the klystron cabinet and water system. Near the end of the project determine if the manpower and down time is available to install the system upstairs, or if would be beneficial to install it downstairs.
Drill penetration into the NDR vault.
During the next several years we will keep updated on
the TV transmitter market and review the reliability of the existing system.
High power solid state drive amplifiers will improve during this time.
There are a number of refurbishment/replacement options