electrospinning +15kV and -4kV = 19kV

[Bill Sloman]

On Tuesday, September 17, 2019 at 4:24:49 PM UTC+10, Tom Gardner wrote:

On 16/09/19 21:26, John Larkin wrote:
On Mon, 16 Sep 2019 12:38:58 -0700 (PDT), sroberts6328@gmail.com
wrote:

So do I, first as a Research Associate and then as a Departmental Senior Technician. Toss in a few years of Field Service and Factory Training Engineer work away from the University. There are weeks that I am totally shocked by the cool gear I get to work on, or design, or modify.

My outside client base was USAF, DOE, Medical, Entertainment, Research when I worked in private industry.

100x Graduate Students, 300 Undergraduate in my department alone...

STEVE



I worked a couple summers in the electronics shop of a university
physics department. Got to help the scientists do all sorts of stuff.
Lot of variety, learned a lot.

That's apparently what Win does, helps science types with the
electronics. Some physicists aren't too good with electronics.

No doubt some physicists/chemists/biologists believe some electronic
engineers aren't too good with physics/chemistry/biology.

The problem with American physicists - I didn't see it in the UK - seems to be that they think that electronics is merely applied physics, and don't take it as seriously as they might.

Sensible people understand that if you immerse yourself in a particular subject you tend to be better at it than people who dabble.

Ernest Rutherford is claimed to have said that "All science is either physics or stamp collecting" which probably reflected the idea that physics was about teasing out fundamental principles, and the flip side of that is the idea that if you understand the fundamental principles you can work out the details - the fact that it can take forever, and some of the details are not all that obvious isn't always appreciated.

--
Bill Sloman, Sydney

 

[John Larkin]

On Tue, 17 Sep 2019 07:24:44 +0100, Tom Gardner
<spamjunk@blueyonder.co.uk> wrote:

On 16/09/19 21:26, John Larkin wrote:
On Mon, 16 Sep 2019 12:38:58 -0700 (PDT), sroberts6328@gmail.com
wrote:

So do I, first as a Research Associate and then as a Departmental Senior Technician. Toss in a few years of Field Service and Factory Training Engineer work away from the University. There are weeks that I am totally shocked by the cool gear I get to work on, or design, or modify.

My outside client base was USAF, DOE, Medical, Entertainment, Research when I worked in private industry.

100x Graduate Students, 300 Undergraduate in my department alone...

STEVE



I worked a couple summers in the electronics shop of a university
physics department. Got to help the scientists do all sorts of stuff.
Lot of variety, learned a lot.

That's apparently what Win does, helps science types with the
electronics. Some physicists aren't too good with electronics.

No doubt some physicists/chemists/biologists believe some electronic
engineers aren't too good with physics/chemistry/biology.

Sure, but practically any scientific experiment these days is
electronics-heavy.

AoE began as an introduction to electronics for scientists.

The Cold Fusion thing was probably just bad instrumentation. The fact
that so many people confirmed the excess energy is scary.

 

[Tom Gardner]

On 17/09/19 17:55, John Larkin wrote:

On Tue, 17 Sep 2019 07:24:44 +0100, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 16/09/19 21:26, John Larkin wrote:
On Mon, 16 Sep 2019 12:38:58 -0700 (PDT), sroberts6328@gmail.com
wrote:

So do I, first as a Research Associate and then as a Departmental Senior Technician. Toss in a few years of Field Service and Factory Training Engineer work away from the University. There are weeks that I am totally shocked by the cool gear I get to work on, or design, or modify.

My outside client base was USAF, DOE, Medical, Entertainment, Research when I worked in private industry.

100x Graduate Students, 300 Undergraduate in my department alone...

STEVE



I worked a couple summers in the electronics shop of a university
physics department. Got to help the scientists do all sorts of stuff.
Lot of variety, learned a lot.

That's apparently what Win does, helps science types with the
electronics. Some physicists aren't too good with electronics.

No doubt some physicists/chemists/biologists believe some electronic
engineers aren't too good with physics/chemistry/biology.


Sure, but practically any scientific experiment these days is
electronics-heavy.

AoE began as an introduction to electronics for scientists.

Both points agreed, but they don't change the point I made.

 

[Bill Sloman]

On Wednesday, September 18, 2019 at 2:56:05 AM UTC+10, John Larkin wrote:

On Tue, 17 Sep 2019 07:24:44 +0100, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 16/09/19 21:26, John Larkin wrote:
On Mon, 16 Sep 2019 12:38:58 -0700 (PDT), sroberts6328@gmail.com
wrote:

So do I, first as a Research Associate and then as a Departmental Senior Technician. Toss in a few years of Field Service and Factory Training Engineer work away from the University. There are weeks that I am totally shocked by the cool gear I get to work on, or design, or modify.

My outside client base was USAF, DOE, Medical, Entertainment, Research when I worked in private industry.

100x Graduate Students, 300 Undergraduate in my department alone...

STEVE



I worked a couple summers in the electronics shop of a university
physics department. Got to help the scientists do all sorts of stuff.
Lot of variety, learned a lot.

That's apparently what Win does, helps science types with the
electronics. Some physicists aren't too good with electronics.

No doubt some physicists/chemists/biologists believe some electronic
engineers aren't too good with physics/chemistry/biology.

Sure, but practically any scientific experiment these days is
electronics-heavy.

AoE began as an introduction to electronics for scientists.

A laboratory course on electronics for scientists at Harvard - thus aimed at bright and motivated students. It got picked up as an undergraduate text at Cambridge in the UK not much later - Cambridge can be just as picky about the students it admits as Harvard. I got onto it when new engineers at Cambridge Instruments had a copy on their desks.

Part of the way I got in to electronics involved David Dewhurst

https://trove.nla.gov.au/people/1476061?c=people

who was professor of physiology at Melbourne at the time and had a half share in the PDP-8 I used. He notoriously found it easier to teach electronic engineers physiology than physiologists electronics, and the stuff he was measuring needed fancy electronics.

The Cold Fusion thing was probably just bad instrumentation. The fact
that so many people confirmed the excess energy is scary.

The fact that so many people confirmed the excess energy does make it unlikely that it was bad instrumentation. The nuclear reaction that might have provided that energy probably wasn't cold fusion, but perhaps rather palladium transmutation to another isotope of palladium by deutron capture, which isn't quite as improbable as cold fusion.

--
Bill Sloman, Sydney

 

[Clifford Heath]

On 18/9/19 5:35 pm, Bill Sloman wrote:

Part of the way I got in to electronics involved David Dewhurst
https://trove.nla.gov.au/people/1476061?c=people
who was professor of physiology at Melbourne at the time and had a half share in the PDP-8 I used. He notoriously found it easier to teach electronic engineers physiology than physiologists electronics, and the stuff he was measuring needed fancy electronics.

Good lord, that's a coincidence. David was a fairly close friend of my
father's, and meeting him inspired me to attempt to qualify in first
Physiology and then in Electrical Engineering, at a time well before all
the modern fad for various forms of combining those as bio-engineering
was the sort of thing people had yet thought of.

When I realised it would involve seven or eight years of study to get
two undergraduate degrees, ans would leave me with no commercial career
options, I thought better of it, and settled on computer science (with
some EE units spliced in) instead.

The first scientific paper I ever saw was David's paper on diagnosing
injury of the knee joint by looking at phase plots of the knee jerk
reflex recorded from an accelerometer attacked to the ankle.

Clifford Heath.

 

[Martin Brown]

On 17/09/2019 15:27, Bill Sloman wrote:

On Tuesday, September 17, 2019 at 4:24:49 PM UTC+10, Tom Gardner
wrote:
On 16/09/19 21:26, John Larkin wrote:
On Mon, 16 Sep 2019 12:38:58 -0700 (PDT), sroberts6328@gmail.com
wrote:

So do I, first as a Research Associate and then as a
Departmental Senior Technician. Toss in a few years of Field
Service and Factory Training Engineer work away from the
University. There are weeks that I am totally shocked by the
cool gear I get to work on, or design, or modify.

My outside client base was USAF, DOE, Medical, Entertainment,
Research when I worked in private industry.

100x Graduate Students, 300 Undergraduate in my department
alone...

I worked a couple summers in the electronics shop of a
university physics department. Got to help the scientists do all
sorts of stuff. Lot of variety, learned a lot.

That's apparently what Win does, helps science types with the
electronics. Some physicists aren't too good with electronics.

No doubt some physicists/chemists/biologists believe some
electronic engineers aren't too good with
physics/chemistry/biology.

The problem with American physicists - I didn't see it in the UK -
seems to be that they think that electronics is merely applied
physics, and don't take it as seriously as they might.

My UK physics course included electronics right from the start. How to
use an oscilloscope was one of the first things taught since many of the
practicals depended on using one. Opamps, FETs and bipolar transistors
were used as concrete examples at various stages.

It also included a course of computing for scientists and electronics
for physicists which went from basic soldering technique as a far as
Karnaugh maps and finite state machines. The final practical was to
design and then make a digital dice. It put those of us with a hobby
electronics background at something of an advantage.

Sensible people understand that if you immerse yourself in a
particular subject you tend to be better at it than people who
dabble.

Certainly some of us were better at it than others. My supervision
partner is now a grey beard at Argonne who keeps their synchrotron
running. UK physicists are quite sought after by US facilities because
they are used to making things work again with string and sealing wax.

Ernest Rutherford is claimed to have said that "All science is either
physics or stamp collecting" which probably reflected the idea that
physics was about teasing out fundamental principles, and the flip
side of that is the idea that if you understand the fundamental
principles you can work out the details - the fact that it can take
forever, and some of the details are not all that obvious isn't
always appreciated.

He didn't anticipate DNA sequencing or AI which now makes molecular
genetics probably one of the most key areas of modern day research.

OTOH Rutherford's field of HEP has pretty much become stamp collecting.

--
Regards,
Martin Brown

 

[Martin Brown]

On 17/09/2019 17:55, John Larkin wrote:

On Tue, 17 Sep 2019 07:24:44 +0100, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 16/09/19 21:26, John Larkin wrote:
On Mon, 16 Sep 2019 12:38:58 -0700 (PDT), sroberts6328@gmail.com
wrote:


No doubt some physicists/chemists/biologists believe some electronic
engineers aren't too good with physics/chemistry/biology.

Sure, but practically any scientific experiment these days is
electronics-heavy.

It has been that way for quite a while too - at least in most cutting
edge physics. Insanely high magnetic fields, ultra low noise amplifiers
chasing ever smaller signals in a noisy environment.

> AoE began as an introduction to electronics for scientists.

It was a nice compendium of circuits that worked for scientists to use
and examples of horrors that don't. I still have a copy on my shelf.

The Cold Fusion thing was probably just bad instrumentation. The fact
that so many people confirmed the excess energy is scary.

The F&P cold fusion thing was almost certainly due to bad calorimetry
(which is notoriously difficult). The experimenters were experienced
electrochemists but were rushed into publication by news that someone
else was about to publish (genuine muon catalysed cold fusion).

https://en.wikipedia.org/wiki/Cold_fusion#History

Lack of neutron emission tends to suggest it wasn't fusion. Isotopic
analysis of their palladium might show if some other side reaction had
occurred (I presume this has been done and drawn a black). Kit to do it
was available at the time.

Compared to the number of experimenters that tried Pd/D2O the number
that reported any kind of success was quite small. For months after the
news broke it was almost impossible to obtain supplies of either. There
are still people who keep on flogging this probably dead horse.

Similar laboratory DIY super conductor manufacture occurred when news of
high temperature LN2 ceramics formulation was in the news.

--
Regards,
Martin Brown

 

DecadentLinuxUserNumeroUno@decadence.org wrote in
news:qlo17u$1pbq$1@gioia.aioe.org:

Winfield Hill <winfieldhill@yahoo.com> wrote in
news:qlml3d094e@drn.newsguy.com:

Cursitor Doom wrote...

On Sun, 15 Sep 2019, Winfield Hill wrote:

As an engineer, it's fun to get involved with atomic-
molecular-nano stuff. And, if it also requires high
voltages, so much the better!

How are you generating them? C-W (or variant) style
multipliers?

Standard high-voltage dc-dc converter modules. Most
are proportional types, which means you add a control
system for their supply voltages.



Is the ripple any issue?

With x-ray I know that the cleaner the HVDC supply, the cleaner
the
flux, and thus the better the contrast ratio of the imagery.

If the supply is overtly noisey, the flux carries so much of it
that the image is very grainy and 'snow-filtrated'.

Seems all you need though are the 'degrees of separation' that
19kV
provides and noise is not an issue as the stream 'spins' out based
on the attraction, not something directly related to the HV
excitation as far as time goes.

So, I am a troll, and everyone comes in and calls me one and says I
do not discuss electronics.

It seems, however, that whenever I do, I get crickets.

My question is relevant.

I didn't think that win was another of these filtertards.

 

On Wed, 18 Sep 2019 10:59:54 +0100, Martin Brown
<'''newspam'''@nezumi.demon.co.uk> wrote:

On 17/09/2019 17:55, John Larkin wrote:
On Tue, 17 Sep 2019 07:24:44 +0100, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:

On 16/09/19 21:26, John Larkin wrote:
On Mon, 16 Sep 2019 12:38:58 -0700 (PDT), sroberts6328@gmail.com
wrote:


No doubt some physicists/chemists/biologists believe some electronic
engineers aren't too good with physics/chemistry/biology.

Sure, but practically any scientific experiment these days is
electronics-heavy.

It has been that way for quite a while too - at least in most cutting
edge physics. Insanely high magnetic fields, ultra low noise amplifiers
chasing ever smaller signals in a noisy environment.

AoE began as an introduction to electronics for scientists.

It was a nice compendium of circuits that worked for scientists to use
and examples of horrors that don't. I still have a copy on my shelf.

The Cold Fusion thing was probably just bad instrumentation. The fact
that so many people confirmed the excess energy is scary.

The F&P cold fusion thing was almost certainly due to bad calorimetry
(which is notoriously difficult). The experimenters were experienced
electrochemists but were rushed into publication by news that someone
else was about to publish (genuine muon catalysed cold fusion).

https://en.wikipedia.org/wiki/Cold_fusion#History

Lack of neutron emission tends to suggest it wasn't fusion. Isotopic
analysis of their palladium might show if some other side reaction had
occurred (I presume this has been done and drawn a black). Kit to do it
was available at the time.

Compared to the number of experimenters that tried Pd/D2O the number
that reported any kind of success was quite small. For months after the
news broke it was almost impossible to obtain supplies of either. There
are still people who keep on flogging this probably dead horse.

Similar laboratory DIY super conductor manufacture occurred when news of
high temperature LN2 ceramics formulation was in the news.

AoE, at a mere 1170 pages, doesn't devote much time to Signals and
Systems; there are bits here and there. Any scientist should get a
separate outline of that.

 

[Winfield Hill]

DecadentLinuxUserNumeroUno@decadence.org wrote...

DecadentLinuxUserNumeroUno@decadence.org wrote
Winfield Hill <winfieldhill@yahoo.com> wrote
Cursitor Doom wrote...
On Sun, 15 Sep 2019, Winfield Hill wrote:

As an engineer, it's fun to get involved with atomic-
molecular-nano stuff. And, if it also requires high
voltages, so much the better!

How are you generating them? C-W (or variant) style
multipliers?

Standard high-voltage dc-dc converter modules. Most
are proportional types, which means you add a control
system for their supply voltages.

Is the ripple any issue?

With x-ray I know that the cleaner the HVDC supply, the cleaner
the flux, and thus the better the contrast ratio of the imagery.

If the supply is overtly noisey, the flux carries so much of it
that the image is very grainy and 'snow-filtrated'.

Seems all you need though are the 'degrees of separation' that
19kV provides and noise is not an issue as the stream 'spins'
out based on the attraction, not something directly related
to the HV excitation as far as time goes.

So, I am a troll, and everyone comes in and calls me one
and says I do not discuss electronics.

It seems, however, that whenever I do, I get crickets.

My question is relevant.

I didn't think that win was another of these filtertards.

No, but I usually don't say anythng unless I have something
to say. You pretty well spelled out the scene, and if I was
forced to guess, I'd imagine that ripple has little effect.
In fact, I haven't measured the ripple on my HV modules.
While I do have a stock of high-V caps, setting up the 20kV
measurement is painful to contemplate, so I'll probably just
take a pass. I am setting up a feedback-loop response test
today, using Ohmite SM108 500M 1% HV resistors. They're
2.1-inches long and rated at 20kV. I promise to be careful.


--
Thanks,
- Win

 

On Sunday, September 15, 2019 at 4:58:11 PM UTC-4, Winfield Hill wrote:

Electrospinning is an interesting technique for making
nanofibers. We used +15kV on the needle of a motorized
syringe pump and -4kV on a collection mat = 19kV total.
The electric field pulls off a thin stream of molecules,
which landed into a random mat of nanocarbon filaments.
My RIS-769 instrument could be adjusted up to 25kV, but
less seemed to work better. Here's its first result.
https://www.dropbox.com/s/i8a3znvfdcvaryc/2017_Jiang_Transition-Metals.pdf?dl=1

I had lots of fun fighting off corona discharge, etc.
Now I'm making s/n 2, improved with its own PCB, etc.,
this time for use with different compounds, to provide
touchless support web for surface-tension experiments.
A safety interlock, adjustable HV voltages, and meter
readout of both voltages and the negative mat current.


--
Thanks,
- Win

Seems there was similar project of artificial photosynthese wherein they created the array by genetically modifying virus particles, multiply them cheaply and in great numbers, and then killing them. The genetic modification was such that residual electrostatics of the virus molecules causes them to self-organize into a perfect array on the nanometer scale they couldn't hope to do otherwise. Then they laid the photo-material onto/into the array using another relatively low-tech process.

 

On Wed, 18 Sep 2019 14:11:40 +0000 (UTC),
DecadentLinuxUserNumeroUno@decadence.org wrote:

DecadentLinuxUserNumeroUno@decadence.org wrote in
news:qlo17u$1pbq$1@gioia.aioe.org:

Winfield Hill <winfieldhill@yahoo.com> wrote in
news:qlml3d094e@drn.newsguy.com:

Cursitor Doom wrote...

On Sun, 15 Sep 2019, Winfield Hill wrote:

As an engineer, it's fun to get involved with atomic-
molecular-nano stuff. And, if it also requires high
voltages, so much the better!

How are you generating them? C-W (or variant) style
multipliers?

Standard high-voltage dc-dc converter modules. Most
are proportional types, which means you add a control
system for their supply voltages.



Is the ripple any issue?

With x-ray I know that the cleaner the HVDC supply, the cleaner
the
flux, and thus the better the contrast ratio of the imagery.

If the supply is overtly noisey, the flux carries so much of it
that the image is very grainy and 'snow-filtrated'.

Seems all you need though are the 'degrees of separation' that
19kV
provides and noise is not an issue as the stream 'spins' out based
on the attraction, not something directly related to the HV
excitation as far as time goes.


So, I am a troll, and everyone comes in and calls me one and says I
do not discuss electronics.

It seems, however, that whenever I do, I get crickets.

My question is relevant.

I didn't think that win was another of these filtertards.

What is your definition of "flux" ?

How does power supply ripple affect x-ray image quality? Xray tubes
emit broadband radiation and maybe a few sharp spectral lines, with
neither affected much by acceleration voltage.

https://en.wikipedia.org/wiki/X-ray_tube#/media/File:TubeSpectrum.jpg

A lot of older medical and dental x-ray machines drove the tube with
unrectified AC.

 

jlarkin@highlandsniptechnology.com wrote in
news:khl4oe1n6coua04t8ualhfu7hjl6camgr8@4ax.com:

What is your definition of "flux" ?

With respect to the generation of X-rays, we (the world) use an
electron beam made via DC to strike a medium which repsonds by
emitting x-rays.

Typically Palladium, typically at a 45 degree angle of incidence.

The resultant emission is referred to by the industry and scientific
community as 'flux'. The 'purity' of that flux determines the
resultant imagery clarity. So, "x-ray flux" would be the full,
proper term for it.

The main consideration for the purity of that flux is the purity of
the DC electron beam splashing into the palladium (or other) ingot.

Whenever an electron beam strikes a metal an x-ray emission occurs.
Different metals respond better. So your old CRT TV screen 'wive's
tale' about it causing one to go blind (or 'get cancer') because of
being situated too close to the TV was true inasmuch as the mask on
the CRT does emit a tiny amount of X-rays. Very tiny. Practically
negligible. More likely get it from the carpets of the day.

I made a 4kV supply for a customer that was x-ray inspecting iron
(IIRC) natural gas lines in Boston (IIRC) for cracks. This supply
had very LOW power capacity, but an *extremely* low ripple figure by
design. It came out to like 0.0006%. The same supply minus the HV
filtration and EOL storage puts out several milliamps at that 4kV
figure, at more realistic ripple values for off the shelf HV use and
sales. This guy, however needed it very clean. Our power supplies
gave him back his profits because it made his imagery so good it was
easier to read and easier to gather making the business more
profitable and sellable. But that x-ray supply had to be real clean.
Thta is when I learned that the purity of that DC exciter determines
the purity of that flux which determines the contrast ratio ond other
elements of the quality of the imagery produced. Think about it.
Porperly emitted and focussed beams make clean optical 'pass
through' images. Noisey beams makes noisey images via random
scattered x-ray flux during the exposure event. Essentially
affecting contrast ratio, which in a monochromatic exposure of film
is paramount.

We also made one with +90kV and -90kV (180kV) excitation that is
what ECG used in the airport x-ray machines that were used for
decades. Not the new ones.

That was in an 80Lb sealed 18 inch by 26 inch by 6 inch lead lined
oil filled tank with a pressure regulating diaphragm. Hottest supply
I ever developed. The tube alone for those is made in Germany and
costs about $900 each. It is like 9 inches long and 2.5 inches in
diameter.

Also made a 50kV 250W supply for LANL to peer into warhead shell
casings (and containment vessels, etc.). That one also had to be
*very* clean. The 3/8" diamter (5 inch long) HV output 'tip' from
the coax had to be inserted into the connection node through a
insulative gel filled 'stab' tube before getting locked in with a std
50Ohm coax connector of the variety we used on CB radios. What was
that RG-58 IIRC.

Why? Did you think I meant solder flux?

Oh, that's right... I get no intellectual credence from you, so
you did not even really read the post at all to start with, OR the
context and term meaning would have been obvious... to anyone I know
claiming to be scientific.

Look at the context, Johnny. Think.

 

jlarkin@highlandsniptechnology.com wrote in
news:khl4oe1n6coua04t8ualhfu7hjl6camgr8@4ax.com:

> How does power supply ripple affect x-ray image quality?

Think of it as injected noise that shows up in the produced flux
stream, that decidedly affects image quality, or the pursuit of clean
HV supplies to drive them would not have evolved.

Xray tubes
emit broadband radiation and maybe a few sharp spectral lines,

But they do so in a pseudo-linear fashion as it splashes off the
target ingot and that flux stream is affected by the DC electron beam
that hits it. That stream then enters an Aluminum lens and becomes
what gets used to pass through the target under test and create the
resultant image. It has nothing to do with the spectral element. We
only need what is able to make it through the item we are trying to
image the internals of. It has to do with the moment by mement
splash of the e-beam into the flux ingot. The polish on the face of
the ingot also matters as it is the first surface involved with the
creation of a nice, pure, clean, mostly linear flux.

with
neither affected much by acceleration voltage.

Overall flux output varies kind of spongey with tens or hundreds
of volts of change. But the noise in that excitation voltage makes
it through and screws up the image quality.

https://en.wikipedia.org/wiki/X-
ray_tube#/media/File:TubeSpectrum.jpg

Again... not about the spectrum.

A lot of older medical and dental x-ray machines drove the tube
with
unrectified AC.

A dental shot is essentially inches from the emitter and the film
is imediately behind the target. Exposure time is a factor and image
quality for certian x-ray results only needed what was needed for the
job. Modern x-ray machines are far more sophisticated.

"unrectified AC"?

Got a citation for that?

 

[Martin Brown]

On 18/09/2019 15:32, jlarkin@highlandsniptechnology.com wrote:

On Wed, 18 Sep 2019 10:59:54 +0100, Martin Brown
'''newspam'''@nezumi.demon.co.uk> wrote:

On 17/09/2019 17:55, John Larkin wrote:

AoE began as an introduction to electronics for scientists.

It was a nice compendium of circuits that worked for scientists to use
and examples of horrors that don't. I still have a copy on my shelf.

AoE, at a mere 1170 pages, doesn't devote much time to Signals and
Systems; there are bits here and there. Any scientist should get a
separate outline of that.

The corresponding Swiss army knife of computing for scientists,
numerical analysis and basic signal processing is "Numerical Recipes" by
Press, Flannery, Teukolsky and Vettering which isn't a bad practical
introduction (although some of their code doesn't quite work and some
algorithms are obfuscated by FORTRAN array starts at 1 indexing). The
bibliography is fine though specialist newer texts are better.

Anything more than that and you are into university signal processing
texts like Digital Signal Processing by Prokalis & Manolakis (sp?) etc.

Linear systems and control theory was a specific final year module aimed
at the best students in my physics course. It covered all the usual
stuff for PID, loop stability up to and including Routh stability test.
It was much more mathematical than the corresponding engineering course.

--
Regards,
Martin Brown

 

On Thu, 19 Sep 2019 07:08:34 +0000 (UTC),
DecadentLinuxUserNumeroUno@decadence.org wrote:

jlarkin@highlandsniptechnology.com wrote in
news:khl4oe1n6coua04t8ualhfu7hjl6camgr8@4ax.com:

How does power supply ripple affect x-ray image quality?

Think of it as injected noise that shows up in the produced flux
stream, that decidedly affects image quality, or the pursuit of clean
HV supplies to drive them would not have evolved.

Xray tubes
emit broadband radiation and maybe a few sharp spectral lines,

But they do so in a pseudo-linear fashion as it splashes off the
target ingot and that flux stream is affected by the DC electron beam
that hits it. That stream then enters an Aluminum lens and becomes
what gets used to pass through the target under test and create the
resultant image. It has nothing to do with the spectral element. We
only need what is able to make it through the item we are trying to
image the internals of. It has to do with the moment by mement
splash of the e-beam into the flux ingot. The polish on the face of
the ingot also matters as it is the first surface involved with the
creation of a nice, pure, clean, mostly linear flux.



with
neither affected much by acceleration voltage.

Overall flux output varies kind of spongey with tens or hundreds
of volts of change. But the noise in that excitation voltage makes
it through and screws up the image quality.

https://en.wikipedia.org/wiki/X-
ray_tube#/media/File:TubeSpectrum.jpg


Again... not about the spectrum.

A lot of older medical and dental x-ray machines drove the tube
with
unrectified AC.

A dental shot is essentially inches from the emitter and the film
is imediately behind the target. Exposure time is a factor and image
quality for certian x-ray results only needed what was needed for the
job. Modern x-ray machines are far more sophisticated.

It's still line-of-sight xray photons. No focussing optics, no
chromatic effects, just pure geometry. Acceleration voltage has almost
no effect on image quality.

"unrectified AC"?

Got a citation for that?

Just hundreds of google hits for xray unrectified ac

Maybe you can find one that relates voltage ripple to image
resolution.

 

jlarkin@highlandsniptechnology.com wrote in
news:9847oeldtng5n72gd26ahde4l5scsr5as3@4ax.com:

Maybe you can find one that relates voltage ripple to image
resolution.

With direct feedback from major customers, I am decidedly certain
that it is related. Sorry to burst your hate me bubble. You can
continue to attempt to come up with something to discredit my knowledge
on this, but I am not going out and hunting up electronic facts for
you.

Otherwise extremely noisey HVPSes would be used and they simply are
not. The reason? Image quality. Customers used us because we were
able to make quiet, repeatable performing supplies, which they had
trouble getting elsewhere. A truly good HVPS is a science and art, and
very application specific as to the level of "cleanliness" required to
perform the task.

On miniature HVPS, one notices that ripple also has an effect on
overall performance efficiency.

Noise has (power) costs depending on where it gets generated at. It
has performance costs if the requisite is a pure DC output as well.
Clean is clean. Parts is parts. HV is HV. Noisey HV is worse than
some simple noisey USB dongle that your phone dislikes and won't go
into fast charge mode over, while other phones do fine. Noisey HVDC is
BAD.

Take a dynode for a PMT for example. Even picoamps of leakage causes
problems. So too can noise in the supply. Not as big an issue there
though.

There are applications where it is optimal. We made supplies that
went up on NOAA weather balloons. We even made a few that NASA bought
in which the test survivor candidate went up on the Shuttle Mission,
while one was literally destroyed in test and the second survivor
candidate perfomred in some minutely lesser way, such that they chose
the one they sent on the mission. NOAA does the same thing. Lots of
waste in redundancy, but mission assurance costs.
That was a nice supply. Fully potted in CONAP rendering them 100% non-
serviceable. Space Ready, however.

We had others where noise did not matter at all... like a getter for
a lamp ignition circuit, where the coiled HV wire was outside the glass
envelope of the lamp, and only the attractive force was needed.

And as far as your unrectified AC claim, I would only ask... "You do
know what a vacuum tube is, right? X-ray tubes are specifically
labelled "ANODE" and "CATHODE". Guess what they get energized by...
it is NOT AC."

 

On Thu, 19 Sep 2019 10:17:55 +0100, Martin Brown
<'''newspam'''@nezumi.demon.co.uk> wrote:

On 18/09/2019 15:32, jlarkin@highlandsniptechnology.com wrote:
On Wed, 18 Sep 2019 10:59:54 +0100, Martin Brown
'''newspam'''@nezumi.demon.co.uk> wrote:

On 17/09/2019 17:55, John Larkin wrote:

AoE began as an introduction to electronics for scientists.

It was a nice compendium of circuits that worked for scientists to use
and examples of horrors that don't. I still have a copy on my shelf.

AoE, at a mere 1170 pages, doesn't devote much time to Signals and
Systems; there are bits here and there. Any scientist should get a
separate outline of that.

The corresponding Swiss army knife of computing for scientists,
numerical analysis and basic signal processing is "Numerical Recipes" by
Press, Flannery, Teukolsky and Vettering which isn't a bad practical
introduction (although some of their code doesn't quite work and some
algorithms are obfuscated by FORTRAN array starts at 1 indexing). The
bibliography is fine though specialist newer texts are better.

Anything more than that and you are into university signal processing
texts like Digital Signal Processing by Prokalis & Manolakis (sp?) etc.

Linear systems and control theory was a specific final year module aimed
at the best students in my physics course. It covered all the usual
stuff for PID, loop stability up to and including Routh stability test.
It was much more mathematical than the corresponding engineering course.

The good thing about my engineering courses in S+S is that we started
with visual, graphical, intuitive concepts of impulse response,
filtering, modulation, convolution. That's what an engineer needs to
design. Being "much more mathematical" is not necessarily a virtue,
especially nowadays when computers can do the grunt work.

 

jlarkin@highlandsniptechnology.com wrote in
news:9847oeldtng5n72gd26ahde4l5scsr5as3@4ax.com:

It's still line-of-sight xray photons. No focussing optics, no
chromatic effects, just pure geometry. Acceleration voltage has
almost no effect on image quality.

Oh but there most certainly is focussing optics.

X-rays are focused by Aluminum lenses.

I did not say that acceleration voltage had an effect. I said that
ripple does.

Do you even know what PARD is?

 

With all due respect, Xrays are not focused by aluminum lenses. They are filtered by shaped aluminum disks or sheets, to prevent the PT from being exposed to the huge amount of low energy X-rays that comes off a typical tube anode, usually made of Tungsten with a touch of Iridium for toughening. These low energy X-rays do make it through the PT to the detector. Thus they just result in extra cumulative dose to the patient if not filtered out.

Aluminum, Nylon, and Beryllium are typical filters used in CT or real Time Imaging X-ray systems.

The Filters are also shaped to avoid hot spots at the detector array from scattering in the frame or from the tube's inherent beam profile. With 64 or 256 detectors in an CT machine array, normalizing the beam is important..

I'll give you an example based on one I worked on.

Modern medical CT machines use dual, split, supplies aka programmable PSUs that can source 80 to 120 Kvp at 10 to 900 mA adjustable. This supply is actually modulated as it spins round the patient with the detectors on the opposite side of the Rotor. 440 VAC slip rings around the patient supply the power. Modulating the supply is used to reduce dose, and it can change tube current very fast during a rotation based on a "prescan" of the PT or real time on the fly calculations.

The supply also provides an auxiliary voltage to drive a deflection plate next to the cathode to slightly move the X-ray beam to enhance resolution by shifting the beam around one detector width along the patient axis. That pulses like crazy

A high tube current such as 800 mA would be used in an emergency "once in a lifetime" scan to quickly find a bleed or injury in the ER. Normal doses are much lower, say 350 mA.

I spent a year as a CT Electronics Trainer...

Steve