INTRODUCTION

STATUS OF RELIABILITY UPGRADES

• INTERLOCKS
• Completion of SDR
• Old electro-mechanical system in SDR and (undocumented) cross-connect wiring has been removed
• Replaced with Alan Bradley Programmable Logic Controller
• Documentation in progress
• NDR system to be done in the next extended downtime
• Components have been ordered (?)

• SPARES
• 1 assembled spare klystron and magnet is now stored in each ring, plus 1 spare upstairs
• future availability issue
• tube lifetime and assumptions about beam power requirements
• KLYSTRON ANCILIARIES
• Water cooling circuits in disrepair
• Tube mechanical mounting worn out, unsafe.
• Systems in the vault are largely undocumented.

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

Availability 98.3%

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
97 1384	52	31	6	10	5	0	96.2
96 1417	48	24	4	2	18	0	96.6
94 2830	65	43	2	15	1	5	97.7
93 3026	57	23	8	21	2	4	98.1
92 1662	43	6	16	7	2	6	97.4

 
 
 

Current Inventory October 4, 1999 http://www.slac.stanford.edu/grp/kly/amrf/drrf/drhist.html
 

S/N	Tube Type	Solenoid	Location	Status	Vac Ion Pump	Warranty	Notes
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.

Magnet Summary

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.

Klystron Summary

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.

1. Interlock to shut off HV power when RF is off for 5 minutes. Reduces the time all the beam power is going to the collector.
2. Tubes with over 20k hours of operation are no longer rebuilt.
3. The beam voltage has been reduced to 21kV, SDR, and 22kV, NDR.

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.
 
 

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.

New system can be moved upstairs in the future.

New cabinet will reduce klystron replacement time by 1 hour and reduce likelihood of errors.

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.
 
 
 
 

SUMMARY

There are a number of refurbishment/replacement options

• Refurbish existing transmitters downstairs
• Requires extended access
• Need to maintain a larger inventory of spares
• Could prepare a new klystron cabinet ahead of time and install complete assembly.

• If a new klystron cabinet is prepared ahead of time, we can also install it upstairs
• Only additional cost comes from pulling new cables to the new location in the support building.
• This cost is offset by the savings in the number of spares inventory (klystrons, magnets, circulator).
• Significant operational and maintenance advantage in this solution.

• Replacing the klystron tube with a new IOT installation requires large capital outlay but has long term power savings.

• The cost per kWH was incorrectly assumed to be $0.22, whereas it is $0.022, making the annual cost savings for the IOT a factor 10 less