Longevity of Micro-sources

[johnewarren]

I am curious as to the actual longevity of X-ray micro-source systems. Basically the systems in the Oxford NOVA/MOVA and the Incoatec systems. I ask because they are sold as "trouble free" alternatives to rotating anode sources which can be left alone and give rock solid performance etc, etc.

The problem is I have a friend in the Henry Moseley Laboratory in Manchester and they have a Hamamatsu microfocus source on their custom Xradia set (not to mention a load of other sources and equipment a really nice lab). The concern comes from the fact that after 1 year the source has been completely replaced? They apparently experienced some drop in performance with time which was more obvious towards the end of the sources life but at one year complete replacement? Not their choice either it was done as part of their service contract.

Not knowing the financials to replace this unit (service contract) I would appreciate knowing if this sort of thing is true in the small molecule world?

Would after buying a SuperNova system I have to replace both sources after a year? How much is it to replace a source? Likewise with the Incoatec system?

It looks like the hardware all use a similar X-ray microfocus sealed tube but differ in their optics design and implementation so I can not see how any one microfocus source will outlast an other if they all buy the X-ray source from one or two oem companies?

Any information would be greatly appreciated.

[feldspar]

What is the difference between a microsource and a normal x-ray source? Just size?

[pmueller]

The technology is too new for decent reliability statistics, but the ImuS from Incoatec is expected to last at least five years. Besides, Incoatec gives you a three year guarantee on the ImuS, so if it braks after two years you get a new one.

[johnewarren]

Is there 5 year life based on a pseudo "normal" operating mode?

That is does it assume the source will be switched off when not in use over weekends or at night etc. When in reality it would be run 24/7 365 days a year?

Also is it assumed that you will not be running at maximum driving voltage? So always at 80% or less full source power?

What is the difference between a microsource and a normal x-ray source? Just size?

They are of approximately equivalent physical size but they difference in the X-ray photon targeted area. In a normal tube the area is quite large but in a micro-source they use a magnetic field to focus down the electrons from the cathode to hit a small (often 20 - 30 micron) area on the anode (I think there are even 6 micron spot sources). They then use optics to take the smaller focal spot source.

[pmueller]

Is there 5 year life based on a pseudo "normal" operating mode?

That is does it assume the source will be switched off when not in use over weekends or at night etc. When in reality it would be run 24/7 365 days a year?

Also is it assumed that you will not be running at maximum driving voltage? So always at 80% or less full source power?

Hi John,

I don't know how they do their predictions and simulations. You could write an e-mail to the Incoatech people -- they are very nice and helpful (they are actually physicists much more than sales people and are always willing to talk tech-stuff). In any case I assume the warranty they give is independent of the use (probably excluding abuse).

Cheers,

Peter

[pmueller]

What is the difference between a microsource and a normal x-ray source? Just size?

They are of approximately equivalent physical size but they difference in the X-ray photon targeted area. In a normal tube the area is quite large but in a micro-source they use a magnetic field to focus down the electrons from the cathode to hit a small (often 20 - 30 micron) area on the anode (I think there are even 6 micron spot sources). They then use optics to take the smaller focal spot source.

The most important practical difference between microsources and regular sealed tubes is that a microsource consumes only about 5% of the power (typically 60 to to 80 W instead of 2 to 2.5 kW) and does not need water cooling. It delivers more photons than a sealed tube albeit on a smaller spot (typical spot sizes range from 100 to 350 microns, compared to the typical 300 to 800 microns for a sealed tube). The photon density (photons per surface irradiated) of some of those microsources are greater than traditional 5kW rotating anodes (specifically the Incoatec ImuS with copper target).

In my opinion the microsource is what the CCD detector was in the early 1990s. This is the new technology that will, over the next 10 years or so, replace the old. As we don't have many serial counters any more, we will see the traditional sealed tube disappear. You get more photons without the need of high voltage and without that annoying water chiller. What's not to like?

[pmueller]

Hi all,

I just came across a very interesting paper comparing a Mo sealed tube with a Mo microsource. They had both tubes mounted on the same goniometer (probably the world's only Mo/Mo dual source instrument) and tested everything rather thoroughly. It is a very good read and quite interesting for anyone in the market for a new instrument:
Schulz et al. (2009). J. Appl. Cryst. 42, 885–891.

Cheers,

Peter

[pmueller]

Hi all,

This topic has been dormant a little and I wonder whether there is anything to answer John's original question:
How long do microsources last in the field? Do any of you have such instruments from any manufacturer or vendor? If so, how often do you need to change tubes? Once a year? Every other year? Never...?

If you wish to remain anonymous, send me a private message or e-mail (pmueller@mit.edu), but I'd appreciate any information I can get, as I am in the market for such an instrument myself now.

Thanks for the input,

Peter

[Zamu]

Hi all,

We are going to buy a new diffractometer this year, most probably with a dual Mo/Cu microfocus source, and I completely agree with Peter: it would be great to have some information about longevity, costs per year (gas,...) and replacement,... to know how it compares economically with sealed-tube or rotating anode sources.

Cheers

Pablo