Important: High voltage clarification

Ji-Won Son jwson at
Thu Mar 18 10:27:30 PST 2004

Hi all,


I asked the procedure to use voltage around 20keV, so I think I can answer
some of David's question. 


The Raith system use 8kV deceleration up to 20keV, so the actual voltage
that applied to the gun is plus 8V to the acc. voltage you choose. (if you
use 20keV, then the actual voltage is 28 V, not 20.) 


Above 20kV, the system turns off 8V deceleration part and applied voltage
will be same as you choose. That's why James asked us to use 10-15 kV and
20.1 - 21 kV at this point to reduce the load. 


I am not sure about using 10-15kV, but when you use 20.1-21kV, the procedure

1. Turn the beam on at 10kV.

2. Check the vacuum. (should be around 10^-9)

3. If vacuum is ok, then change the voltage to 20.1-21kV, by one step. Don't
ramp up slowly step by step! 


These are what I heard from Raith field service. James, if there is anything
wrong with these, please correct. 


Thank you.




Ji-Won Son


(Office) 650-723-4940

(Fax) 650-725-3459



-----Original Message-----
From: David Goldhaber-Gordon [mailto:goldhaber-gordon at] 
Sent: Thursday, March 18, 2004 6:56 AM
To: 'James Conway'; 'John Cumings'
Cc: 'Raith SNF Mailing list'
Subject: Important: High voltage clarification


Hi all,


Thanks and congratulations are due to James for pushing so hard to get the

system up before he leaves for Germany.


I want to clarify one point: James probably meant that the voltages me may

use are 10-15 kV or 20.1 to 21 kV (i.e. 20100 to 21000 V). I point this out

since the actual numbers may be important and I'd hate for someone to

misunderstand and jeopardize the system for him- or herself and others.

James, please post a correction if I got this wrong. Also, could someone

comment on the proper procedure for getting up to those voltages? I'm not

sure that procedure has been uniformly agreed upon and communicated.







David Goldhaber-Gordon                         goldhaber-gordon at

Assistant Professor of Physics                 davidg at

Stanford University                            (permanent forwarding)


(650) 725-2047 (lab)                           (650) 724-3709 (office)


Address for letters or packages:               Administrative Associate:

David Goldhaber-Gordon                         Roberta Edwards

Geballe Laboratory for Advanced Materials      McCullough, Rm. 338

McCullough Building, Room 346                  Phone: (650) 723-8028

476 Lomita Mall                                Fax: (650) 724-3681

Stanford, CA 94305-4045                        email: redward at

-----Original Message-----

From: James Conway [mailto:jwc at] 

Sent: Wednesday, March 17, 2004 8:25 PM

To: John Cumings

Cc: Raith SNF Mailing list

Subject: Re: Raith is being qualified... Thread: Required Limits of keV

operation through 6APRIL2004 on RAITH 150


Please Everyone:


We would like to operate the system in a range between  10 - 15 KeV and/or

at 20100 to 2100 kV only. NOT 20 kV or higher than 21 kV.


 When  I return from Germany and with LEO field service we will perform

further testing on the column.  



Things are in good order and tomorrow I plan to put the system back into

green light mode as more measurements and imaging is completed


Stitching Mean + 3 sigma was 19 nm.


Thanks to everyone for your support during this challenging period,





John Cumings wrote:




Green light means 30 kV is okay.


I presume you mean yellow light, because 30 kV is not okay, correct?





     John Cumings

     cumings at 

     Postdoctoral Scholar

     Physics Department

     Stanford University                        


     office (650) 725-1025

     lab (650) 725-2047

     fax (650) 724-3681


     Geballe Laboratory for Advanced Materials

     239 McCullough Building

     476 Lomita Mall

     Stanford, CA 94305-4045


In message <4058B6CE.7060400 at>you write:


<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">



 <meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1">



<body text="#000000" bgcolor="#ffffff">




I am most relieved to report that we are coming back into normal

operational status on the RAITH 150 system.<br>


This afternoon and evening we will be qualifying the system and working

with users whom are in crisis mode.<br>


We hope to go into green light mode in the next twelve hours.<br>


James Conway<br>





-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the raith mailing list