1. Experiencing MPOD and Module HV Testing By Thomas Pak (Fairfax, VA, USA) Straw Workgroup Meeting Date: December 12 th, 2012 Location: CERN 6-2-024 CERN Supervisor: Hans Danielsson Institute Supervisor: Phil Rubin

2. What is MPOD? HV/LV Power Supply Module with network connectivity, controllability, and programmability Using SNMP for Network Protocol for communication and TCP/IP web access support

3. What is MPOD for Straw Module? Provides HV power to straws – cover by cover or by number of covers - and LV power to readout boards Enables users to monitor the status of the straw modules via MPOD’s supported network protocols Enable users to program the power supply’s behavior (such as maximum current and voltage, and scheduled behaviors)

4. Various Control Methods & Software Web access (TCP/IP, SNMP,Read-only) MUSEcontrol (via USB connection, Windows) Labview Controls (TCP/IP, SNMP) OPC Server (SNMP,TCP/IP, CAN-bus)  Industry standard, as well as CERN standard Software Development(C++ library accessible)

5. Pros and Cons on Each Method Web access ▫Read-only, low current resolution(μA) ▫Can be monitored even through mobile devices MUSEcontrol ▫Full control Access, cannot be used to Remote Control Labview Controls ▫Doesn’t work well, low current resolution(μA) OPC Server ▫Overkill for small systems, high current resolution(nA) ▫Scriptable & widely supported ▫Free browsers available, but moderate to poor quality ▫Hard to see the readings, In-dept development in PVSS needed Software Development(C++ library accessible,SNMP) ▫Can be developed in-house, low current resolution (μA) ▫Fully Controllable

6. OPC Server & PVSS TCP/IP, SNMP OPC Server PVSS ethernet users Straw Module

7. In-House Software Development TCP/IP, SNMP Windows/Visual Studio 2008 ethernet users Straw Module

8. In-House Software Development LV Channels HV ISEG Module Channels Channel ON

9. Module HV Testing 2 nd stage of HV test, following by 1 st web-only HV test and followed by 3 rd stage HV module noise-test The primary goal is to make sure there’s no current leakage

10. HV Testing Process Stage 1: Web-only HV Test Clean HV capacitors Check for current leakage Check for noise-level Stage 2: Module HV Test Check for current leakage Train the Straws under HV pressure Stage 3: Module HV Noise Test Check for Noise Level

11. Straws Behavior under HV 18nFEach straw acts like an 18nF capacitor Under “normal” ambient conditions, it takes about 123 seconds to fully charge up. (2.3kV & 330nA current limit) Initial charging time varies widely between each straw. ( It could be anything 2 minutes ~ 48 hours) Once a straw gets “trained fully” under HV, all straws have a unique rise-time of about ~123 sec. 2 groups of current leakage behavior ▫1~2nA : Does not recurr, when tested again ▫20~25nA: Happens every time, but can be eliminated, when HV lowered to 1.9kV ~ 2.0kV

12. Why do straws need HV training? (Speculation 1) Solid States Problem ▫There are always crystal structure defects, even on the highest quality ultrasonic coating. - - - - - - - - - - potential gradients defects in crystalline structure? Electrons trapped in potential gradients due to defects in crystalline structure? BEFORE HV Training Cu & Au Coating Surface BEFORE HV Training AFTER HV Training Cu & Au Coating Surface AFTER HV Training

13. Why do straws need HV training? (Speculation 1) Moist inside the Straws ▫which under HV would dry up and inhibit leakage (Speculation 3) Current Leakage to the module chassis ▫Not very likely.

14. Acknowledgement Thank you all, straw team members, for your generous support. I’ve learned so many invaluable lessons. This has been one of the best times in my life with learning experiences that would last for long time.