From: Bellomo, Paul
Sent: Thursday, September 29, 2005 12:00 PM
To: Luchini, Kristi
Cc: Carr, Roger; MacNair, Dave; de Lira, Antonio C
Subject: RE: Period of cosine for magnets

Kristi/Roger:

 

Linear and cosine ramp functions are built into the Bitbus and new Ethernet power supply controllers and  part of the command sets.

 

Externally, in software, the Operator sets the desired:

 

1. Linear or cosine ramp

2. Minimum and maximum magnet currents

3. Maximum allowable and average di/dt

4. From the di/dt specification the controller calculates the ramp time

5. Number of up and down repetitions of the ramp (and possibly the dwell intervals between ramps) 

 

Note that software will probably have to be written to implement the ramp parameters that I have described above.

 

Dave MacNair would be very happy to discuss this in detail with you and to offer help.

 

Paul Bellomo

Stanford Linear Accelerator Center, MS 49

2575 Sand Hill Road

Menlo Park, CA 94025

Office:  650-926-2342

Cell:    925-963-0314

http://www.slac.stanford.edu

 

 

-----Original Message-----
From: Luchini, Kristi 
Sent: Thursday, September 29, 2005 11:24 AM
To: Bellomo, Paul
Cc: Carr, Roger
Subject: FW: Period of cosine for magnets

 

Hi Paul,

 

Roger Carr wanted to gather some information on setting a magnet ps during a standardize and during normal operation. Roger wants to know the period of the cosine (when ramping). Roger said that a cosine ramp was used with bitbus controllers in PEPII and SPEAR. As the controls magnet code for PEPII and SPEAR doesn't do anything with cosine when setting a desired field for a magnet we are assuming that what Roger is referring to is done in the bitbus controller itself. We are guessing that this will also be done in the SLAC Ethernet Controller used for intermediate and large power supplies in the injector and BC1. Is there a table that define the period of the cosine depending on the distance you are moving or the ramp speed, or is it just a flat number, or is it done in hardware and not software? 

I would appreciate any help  you could offer in answering Roger's question.

 

Thanks,

- Kristi