Designed to
enhance the sensitivity and versatility of our TOFMS instruments
by providing long term ion storage in the source
region. A drawback of TOF devices
is the lack of a means of storing ions prior to analysis. This
inability to store ions compared to trap methods such as FTICR
and ITMS place TOF at a disadvantage in terms of being able to
manipulate ions for MS/MS or ion-molecule experiments, or for
enhancing sensitivity through storage and integration of the signal.
The QUADRUPOLE ION TRAP can be used to overcome these limitations. Ions can be created and stored during the time between extraction pulses. Approximately 125 microseconds are required for Ion extraction and return to trapping RF potential. It can be seen that duty cycle approaches 100% for storage times of over 10 milliseconds.
The mechanical assembly is 1.75 in. square by 1.25 in. high and is machined to mount to our standard ion source.
One end cap
is center bored with a choice of diameters. This opening is covered
with a 90% transparency mesh to provide an extraction grid. The
opposing end cap can be bored for injection of ions or electrons
if desired. An end cap mounted EGUN is currently being developed.
The center ring can be bored and cross bored for passage of laser
beams, molecular beams, sample probes, etc. This ring is designed
in two pieces for ease of modification and cleaning. This also
allows the replacement of only the damaged part should it become
necessary.
The elements of the assembly are held together with through bolts and ceramic spacers. Ceramic sealing rings can be added if desired in order to contain neutral species, increase local pressure inside the trap or prevent back migration of unwanted species into the trap. Materials of construction are 304 Stainless Steel and Alumina.
The assembly can be installed at the time of manufacture of a TOF or retrofitted to most instruments manufactured by us.
This power supply was designed to provide RF voltage to the C-1251 Ion Trap. Following is a brief description.
Size
(approximately), rack mounted. 19"W x 7"H x 16"D
Input voltage (power requirements) 100/120/220/240, 50/60 Hz
Output voltage and frequency 4000Vp-p at 1 Megahertz
The D-1203 Ion Trap Power Supply has the ability to operate at bias voltages of up to 3500V, adding experimental flexibility.
The D-1203 Ion Trap Power Supply comes equipped with a power meter which reads the power required to drive the C-1251 Quadrupole Ion Trap. It also has two LED's which indicate excess power consumption. One of these is fixed and will light at 50 watts power The sensitivity of other one can be adjusted by the user to indicate a dirty trap or excess gas pressure.
An overcurrent indicator is provided to warn the user of a short or malfunction such as a mis-connection. (the trap must be connected with the furnished 6' cables for proper operation at 1 Mhz).
The D-1203 Ion Trap Power Supply contains the pulse voltage power supply to drive the D-1040 Remote Pulser. It controls the storage time and extraction pulse timing, and shut-off of the RF. The extraction pulse can also be synchronized with the RF phase. This is valuable when extracting ions with the RF turned on (a way to increase the duty cycle and/or repetition rate). RF voltage can be shut down in ½-cycle at 750V and 2 cycles at 3000V RF.
D-1230 RF POWER SUPPLY
This power
supply was designed to provide RF voltage to the C-1251 Quadrupole
Ion Trap. It
is a lower power version of the D-1203. It cannot be floated and
has no driver for the pulser. It is designed to be used either
with our Dual Output Push/Pull Pulser (D-1050, info below) or
our D-1040 Pulser and D-1003 Power Supply. Following is a brief
description.
Size (approximately),
rack mounted. 19"W x 3.5"H x 8"D
Input voltage (power requirements) 85-265VAC, 50/60 Hz
Output voltage and frequency 2500Vp-p at 1 Megahertz.
Must be operated with the furnished RF output cable which is five feet long. For economic reasons, the complexity of the unit was strictly controlled. No elements were included which were not absolutely necessary.
The following
is just one of many possible operation modes. 2500V. RF at 1 MHz
is applied to the ring by the D-1230 RF
Power Supply.
Ions can now be generated inside the trap, or created externally, then injected into the trap through the end cap. They will remain in the trap under these conditions for as long as two seconds.
When the RF
Power Supply receives a TTL trigger pulse from a computer or some
other external source, it shuts down the RF
for an interval equal to the pulse duration. After an additional
preset time delay, the Pulser (D-1040) dips the extraction end
cap by 11 to -400V, or pulses the repeller end cap by 11 to +400V
(D-1050 Dual Pulser: +950/-950V, extractor and repeller) and all
ions are extracted from the trap, (usually within 3µsec)
and accelerate down range to the detector. The trap then returns
to the stable mode to accumulate ions for the next extraction
pulse.
This can be repeated up to 10,000 times per second with 97 microsecond storage time. Spectra will not overlap up to m/e=500 when used with our AREF (D-850) and these input conditions.
It should be noted and emphasized that this equipment was designed for pulsed extraction into a TOFMS or similar experiment. It will not work in the usual "mass selective instability" mode.
D-1050 DUAL OUTPUT PUSH/PULL PULSER
For use when ions are generated at ground potential, such as in an Ion Trap. This Pulser offers dual, simultaneous outputs independently adjustable from plus and minus 0 to 950V, for a total of a 1900V differential.
A system of grids, tubes and apertures which shield, focus and isolate the extracted ion packets between the ion trap and the flight tube. The design of this assembly is critical due to the large difference between pressures in the Ion Trap and the Flight Tube. Each application is individually engineered.
One of many possible configurations of an ion generation/storage device. The assembly consists of the C-950 EGUN and C-1251 Ion Trap mounted on a 6 inch or larger flange. Ions can be pulsed from this device directly through an acceleration grid and into a flight tube for mass separation and analysis.
Ions are generated in the space between the plates which separate the EGUN and Ion Trap. They can be created by electron bombardment and/or laser excitation. The ions are then extracted and focused through the end cap aperture, into the ion trap. Use of a split Einsel tube allows some correction for initial molecular beam velocity as well as providing ion transport. The voltage on one of the tube halves can be stepped for gating purposes.
The components are mounted on insulators so that the entire assembly can be operated at elevated potential. In this case, guard rings would be needed around the trap to minimize ion leakage. All our relevant power supplies are capable of being biased to 5KV for this purpose.
A tube is provided through the flange for introduction of helium or other buffer gas.
The 6.0 inch dimension shown is standard protrustion. Other lengths can be provided to adapt to chamber dimensions and beam geometry.
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